ben m
Joined: 15 Sep 2002
Posts: 344
Location: UK |
| Week 8 - MIDI |
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Lots of lovely MIDI questions this week;
01 - What does MIDI stand for?
02 - Is MIDI a serial or parallel data flow?
03 - How does MIDI data contain timing information?
04 - What are the advantages and disadvantages of MIDI over digital audio?
05 - Briefly describe the General MIDI standard
06 - What other standards have evolved from GM?
07 - What is the data rate of MIDI information in kbits?
08 - What is a UART?
09 - What purpose does a MIDI Thru connection serve?
10 - What is daisy-chaining in terms of MIDI connectivity, and what are its
disadvantages?
11 - What are the advantages of multi-port MIDI interfaces?
12 - What is a MIDI channel?
13 - With reference to the MIDI interface and the MIDI specification explain why MIDI systems can only have 16 channels?
14 - What channel must be used for drums/percussion under the GM standard?
15 - What does Omni mean in terms of the reception of MIDI information on discrete channels?
16 - What is the status byte and what information will it typically include?
17 - What information is typically found in the data byte?
18 - Describe the three bytes of a MIDI note-on message.
19 - What are control change (cc) messages?
20 - What is the purpose of system exclusive (sysex) messages?
21 - What is the difference between channel and system messages?
22 - What MIDI note number is the musical note C3 on a MIDI keyboard?
23 - How may velocity values are there?
24 - What is 'running status'?
25 - In running status, why is a velocity value of 0 treated as a note off message?
26 - What is the purpose of the 'Local' setting on MIDI devices?
27 - What are system realtime messages?
28 - What are Song position pointers (SPPs)?
29 - Briefly describe the MIDI TimeCode (MTC) protocol.
30 - Briefly describe the MIDI Machine Control (MMC) protocol.
31 - Why are modulation wheels often found on MIDI keyboards?
32 - Define the term polyphony.
33 - Define the term multi-timbral
34 - What is aftertouch?
35 - What features do mixing consoles offer that can be controlled by MIDI?
36 - How do MIDI messages such as modulation, expression attempt to recreate the nuances of 'real instruments'?
37 - List eight types of MIDI message which are either System Common or System Real Time. (Hint: these are messages that are NOT identified by MIDI Channel numbers).
38 - List four synchronisation strategies used in MIDI music production that can be used, with appropriate equipment, to synchronise a MIDI sequencer and a multitrack audio recorder. Expand any abbreviations.
39 - MIDI timecode quarter-frame, song position pointer, song select, tune request and end of exclusive are all what type of MIDI message?
40 - What does the first bit of each byte of a MIDI message signify?
41 - Explain the relationship of sequencer tracks, MIDI channels and synthesiser voices.
42 - In a MIDI set up using a MIDI keyboard controller and a computer sequencer what methods may you be able to use to physically input MIDI control data? Give three.
43 - You have a cable with a 5-pin DIN connector at each end. If it is suitable for copying a recording from one cassette deck to another, would it be suitable for MIDI?
44 - What data is provided by a MIDI THRU connector?
45 - What would you be most likely to use the MIDI OUT connector for on a keyboardless MIDI sound module
46 - You are using a MIDI sequencer to record many complex tracks to be played on a MIDI system where several modules are chained together, THRU to IN. What might happen if you use Pitch Bend or Control Change messages excessively?
47 - Some MIDI equipment processes data from the IN connector before sending it to the THRU. What effect does this have on timing?
48 - You are mixing MTC on the same cable as musical data. How might this affect the timing of notes?
49 - You have connected a keyboard with 32 note polyphony to a sequencer and you find that it is only capable of 16 note polyphony when played manually. If the keyboard can give the full 32 notes when disconnected from the sequencer what has happened?
50 - You are recording a melody into a sequencer. The melody contains a complex series of notes and pitch bend movements and you can’t get both the notes and pitch bend moves right simultaneously. What should you do?
51 - You have recorded a piano sound into a sequencer performed by a keyboard player who tends to use the sustain pedal a lot. What problem might you find if you record another piano part on the same MIDI channel?
52 - You have sampled a four bar drum loop and you trigger it from the sequencer on the first beat of bar 1. You also trigger it on the first beat of bar 5. What will happen if you play the sequence from bar 3? |
Mon Apr 25, 2005 3:54 pm |
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rachelh
Joined: 16 Jan 2005
Posts: 35
Location: Trinidad WI |
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Week 8 – MIDI
Submitted by: Rachel
01 - What does MIDI stand for?
MIDI abbreviates for Musical Instrument Digital Interface.
02 - Is MIDI a serial or parallel data flow?
MIDI supports a serial data flow, with the processing speed being 31.25 kbaud/ bits per second. These messages are transmitted through a single MIDI line; this data can only travel in one direction from a single source to a destination. In order to make two-way communication possible, a second MIDI data line must be sued to communicate data back to the first device. [1]
03 - How does MIDI data contain timing information?
Timing information is contained in MIDI Time Code or MTC, which allow time based code and commands to be distributed throughout the MIDI chain. [1]
04 - What are the advantages and disadvantages of MIDI over digital audio?
MIDI is simply a series of performance commands unlike digital audio, which actually encodes the audio information itself. The data processing overhead is extremely low than that associated with digital audio, what this means is that almost no processing power is required to play MIDI, making it ideal for playing real-time music scores while browsing text, graphics and media over the Web. [1]
05 - Briefly describe the General MIDI standard
The General MIDI standard makes it possible for a sound card or “GM” compatible device to play back a score using the originally intended sounds and program settings. [1]
06 - What other standards have evolved from GM?
Other standards that have evolved from GM are that MIDI scores are now integrated into multimedia games, text document, CD-ROMs and websites. [1]
07 - What is the data rate of MIDI information in kbits?
The data rate of MIDI information is 3 kbits per second.
08 - What is a UART?
UART stands for Universal Asynchronous Receiver/ Transmitter; it is an integrated chip, which interfaces a microprocessor to a serial I/O port. [2]
09 - What purpose does a MIDI Thru connection serve?
The MIDI thru connection provides an exact copy of the information being received from the MIDI port and transmits this data out to another MIDI instrument or device that follows in the connected MIDI chain. Thus, the MIDI thru port is the link between MIDI devices and instruments. [1]
10 - What is daisy chaining in terms of MIDI connectivity, and what are its disadvantages?
The daisy-chain with respect to MIDI connectivity describes the process by which one MIDI device is linked to the next by re-transmitting data that is received by a device’s MIDI in port to another device through its thru port [or MIDI echo] port. The disadvantages of daisy chaining stem from the chaining itself, which would become cumbersome if many devices are being used – cables would be literally everywhere and it would be hard to decipher where the problem is- if there is a problem in the chain. [1]
11 - What are the advantages of multi-port MIDI interfaces?
The advantages of multi-port MIDI interfaces are that they allow more devices to be connected into that interface thus cutting down on the number of devices used also there would be less ‘chaining’ to be done as all of the devices can be connected to the interface [where applicable] and then connected to the PC or alternative final output device.
12 - What is a MIDI channel?
An MIDI channel refers to the process by which MIDI can be directed out to a specific device or range of devices via a user-defined channel. [1]
13 - With reference to the MIDI interface and the MIDI specification explain why MIDI systems can only have 16 channels?
MIDI systems have only 16 channels because MIDI can be directed out to a specific device or range of devices via a user-defined channel – this is done by embedding a nibble or 4 bits within the status/ channel number byte that makes it possible for performance or control information to be communicated to a specific device or one of the sound generators in a device over its own channel. Thus 16 are channels are a practical choice due mainly in part by the size of a nibble. [1]
14 - What channel must be used for drums/percussion under the GM standard?
The channel that must be used for drums/ percussion under the GM standard is channel 9. [1]
15 - What does Omni mean in terms of the reception of MIDI information on discrete channels?
The term ‘omni’ in terms of the reception of MIDI information on discrete channels means that the instrument would respond to MIDI coming in on any channel – it is the basic mode for MIDI and is associated with polyphonic sounds. [2][1]
16 - What is the status byte and what information will it typically include?
Status bite is the portion of a MIDI message that defines the type of information being sent- they are identifiers that tell the receiving device which particular MIDI function and channel are being addressed via a MIDI channel. This prepares the device to receive any one of the following eight fundamental types of MIDI data messages: Note Off, Note On, Polyphonic Aftertouch, Control Change (a.k.a. continuous controller), Program Change, Channel Aftertouch, or System. The final type, system, refers broadly to system common, system real time, or system exclusive commands - these are not addressed to individual MIDI channels and the data bits normally used to specify MIDI channel are instead used to further specify the system message. Status bytes are usually followed by one or more data bytes that provide the actual information to be implemented. [1] [2]
17 - What information is typically found in the data byte?
The information found in the data byte typically is used to encode the actual numeric values that accompany the status byte. “Although a byte is made up of 8 bits, the most significant bit [MSB – the leftmost binary bit within a binary word] is used solely to identify the byte type. The MSB of a status byte is always 1, while the MSB of a data byte is always 0. [1]
18 - Describe the three bytes of a MIDI note-on message.
The 3 byte note-on message is used to signal the beginning of a MIDI note. It will transmit instructions that would be read as - transmitting a note-on message over MIDI channel #2, using keynote # 12 at an attack velocity / note volume level of 80. [1]
19 - What are control change (cc) messages?
With MIDI, you can change many settings with foot pedals, modulation wheels, switches, breath controllers, data increment/decrement buttons and sliders, etc. MIDI can transmit such changes with the Control Change set of messages. A MIDI Control Change number is followed by a value that sets the parameter in the MIDI device. The CC Number is a numbered MIDI message that's in many cases permanently assigned to a particular parameter that receives it - controller message, alter note parameters (eg. envelope amount). [2][3]
20 - What is the purpose of system exclusive (sysex) messages?
System exclusive messages or sysex messages allows MIDI manufactures, designers and programmers to communicate MIDI messages between MIDI devices, these messages being specified in nature. This is supposed to give manufacturers, designers and programmers the liberty to communicate any device specific data of an unrestricted length, as they see fit. This data is used commonly for bulk transmission and reception of program/ patch data, sample data and real-time control over a device’s parameters. [1]
21 - What is the difference between channel and system messages?
The difference between channel and system messages is that channel messages are that channel messages are used to transmit real-time performance throughout a connected MIDI system whereas system messages are globally transmitted to every device in a MIDI chain. [1]
22 - What MIDI note number is the musical note C3 on a MIDI keyboard?
The MIDI note number that is the musical note C3 on a MIDI keyboard is the piano would be Middle C, which relates to a note number of 60. ??
23 - How may velocity values are there?
The number of velocity values in a MIDI keyboard is 128, ranging from 0 to 127.
24 - What is 'running status'?
Running status is a method or means of regulating the transfer of data on a MIDI interface. The product of the running status ensures that only one status byte can be active at any one time- this is a preventative for multiple on- status bytes.
25 - In running status, why is a velocity value of 0 treated as a note off message?
The velocity value of 0 is treated as a note off message in running status because ‘0’ symbolises that the note is not existent – meaning that the note has finished sounding, thus, alleviates the need to send note-off messages.
26 - What is the purpose of the 'Local' setting on MIDI devices?
The Local setting on MIDI devices serves the purpose of allowing and /or disallowing MIDI data to be able to flow through the devices, mainly the MIDI keyboard to the final output device.
27 - What are system real-time messages?
System real-time messages are those that are used to coordinate the timing of the equipment to the ensure accuracy of data being transferred.
28 - What are Song position pointers (SPPs)?
Song position pointers (SPPs) allow a sequencer or drum machine to be synchronised to an external source such as a tape machine from any measure position within a song. Although SSPs are used less often than MIDI Time Code [MTC], it can synchronise a location in a MIDI sequence in measure to a matching position point on an external device such as a drum machine or a tape recorder, by providing timing reference that increments once for every six MIDI clock messages with respect to the beginning of a song. [1]
29 - Briefly describe the MIDI Time Code (MTC) protocol.
Timing information is contained in MIDI Time Code or MTC, which allow time based code and commands to be distributed throughout the MIDI chain. MTC provides a cost- effective and easily implemented way of transmitting SMPTE - Society of Motion Picture and Television Engineers time code into a format that conforms to MIDI 1.0 specification. [1]
30 - Briefly describe the MIDI Machine Control (MMC) protocol.
MIDI Machine Control [MMC] protocol is A part of the MIDI spec that allows MIDI devices to control hardware devices, MIDI Machine Control is commonly used to send transport control messages to hardware recorders. Play, Stop, and Locate are examples of MMC messages. MMC does not include synchronization information, although MIDI sync info could also be sent to/from the device that MMC is addressing. MMC allows you to centralize control of your studio from a MIDI source (often a sequencer) [2]
31 - Why are modulation wheels often found on MIDI keyboards?
Modulation wheels are controllers found on keyboards such as MIDI controllers and synthesisers, which takes its shape in the form of a wheel mounted perpendicular to the surface of the keyboard. The wheel itself is imbedded in the surface such that only the top half protrudes. The mod wheel is used to add expression or to modulate (change) various elements of a synthesized sound or sample. One typical use is to modulate an LFO in order to produce vibrato. Another would be to control the speed of rotary speaker emulation. There are many other applications as well depending upon the architecture of the instrument being controlled. [2]
32 - Define the term polyphony.
The term polyphony describes the ability to play more than one note simultaneously on a musical instrument. The more notes of polyphony an instrument can produce, the more capable it is of playing complex arrangements and chords. If the polyphony of the instrument is exceeded, it must "steal" the notes it needs from others that are already sounding. For example, a synthesizer might steal the last note requested from the first one hit; the first note stops, and the new one begins to sound. Some synths and samplers use sophisticated algorithms for voice stealing, others allow you to pre-allocate a given number of voices to a particular MIDI channel, and so on. A six-string guitar has a maximum of 6-note polyphony whilst synthesizer might be 32-note polyphonic. [2]
33 - Define the term multi-timbral
The term multi-timbral describes an instrument that is it is capable of producing more than one type of sound or timbre at a time - Usually this is described as the number of "parts" a unit can play at once For example, a Kurzweil K2500 is 16-part multitimbral, meaning it can produce 16 different sounds at once (a sound being defined as a single patch or preset; part one might be piano, part two strings, part three trombone, part four flute. Generally these parts are assigned to different MIDI channels for independent control). This is distinct from the amount of polyphony, or number of actual notes the unit can simultaneously generate. [2]
34 - What is aftertouch?
After touch is MIDI data sent when pressure is applied to a keyboard after the key has been struck, and while it is being held down or sustained. Aftertouch is often routed to control vibrato, volume, and other parameters. There are two types: The most common is Channel Aftertouch (also known as Channel Pressure, Mono Aftertouch, and Mono Pressure) which looks at the keys being held, and transmits only the highest aftertouch value among them. Less common is Polyphonic Aftertouch, which allows each key being held to transmit a separate, independent aftertouch value. While polyphonic aftertouch can be extremely expressive, it can also be difficult for the unskilled to control, and can result in the transmission a great deal of unnecessary MIDI data, eating bandwidth and slowing MIDI response time. [2]
35 - What features do mixing consoles offer that can be controlled by MIDI?
Features offered by consoles that can be controlled by MIDI are volume, mute groups and amplifier controls.
36 - How do MIDI messages such as modulation, expression attempt to recreate the nuances of 'real instruments'?
MIDI messages such as modulation, expression attempt to recreate the nuances of 'real instruments' by mimicking the tonal qualities of instruments such as pitch, vibrato to accentuate depth, and crescendos and decrescendos, to increase and reduce intensity of a sound.
37 - List eight types of MIDI message, which are either System Common or System Real Time. (Hint: these are messages that are NOT identified by MIDI Channel numbers).
I. Program Change
II. Tune Request
III. Active sensing
IV. System Reset
V. Song position
VI. Song Select
VII. MIDI Clock
VIII. All Notes off
38 - List four synchronisation strategies used in MIDI music production that can be used, with appropriate equipment, to synchronise a MIDI sequencer and a multitrack audio recorder. Expand any abbreviations.
Four synchronisation strategies used in MIDI music production that can be used, with appropriate equipment, to synchronise a MIDI sequencer and a multitrack audio recorder are:
I. MIDI Time Code which provides a cost effective and easy way to transmit SMPTE -Society of Motion Picture and Television Engineers time Code. Society of Motion Picture and Television Engineers time code which is a format that conforms to the MIDI 1.0 specification
II. Sound Select message which is used to request a specific sound from the internal sequence memory of a drum machine or sequencer as identified by its song ID number, after being selected, the song responds to MIDI start, stop and continue messages.
III. Sound Position Pointer, which allows a sequencer or a drum machine to be synchronised to an external source such as a multitrack. It can synchronise a location in a MIDI drum machine or tape recorder by providing timing reference that increments once for every 6 MIDI clock messages, with respect to the beginning of a song.
IV. Tune request – which is used to request that an equipped MIDI instrument indicate its internal tuning routine.
39 - MIDI timecode quarter-frame, song position pointer, song select, tune request and end of exclusive are all what type of MIDI message?
All of the above mentioned messages are real time MIDI messages.
40 - What does the first bit of each byte of a MIDI message signify?
The information found in the data byte typically is used to encode the actual numeric values that accompany the status byte. “Although a byte is made up of 8 bits, the most significant bit [MSB – the leftmost binary bit or the first byte within a binary word] is used solely to identify the byte type. The MSB of a status byte is always 1, while the MSB of a data byte is always 0. [1]
41 - Explain the relationship of sequencer tracks, MIDI channels and synthesiser voices.
The relationship between sequencer tracks, MIDI channels and synthesiser voices stem from
42 - In a MIDI set up using a MIDI keyboard controller and a computer sequencer what methods may you be able to use to physically input MIDI control data? Give three.
Drum machine, effects devices and modules??????
43 - You have a cable with a 5-pin DIN connector at each end. If it were suitable for copying a recording from one cassette deck to another, would it be suitable for MIDI?
MIDI utilises shielded, twisted pair of conductor wires that has a male 5-pin DIN plug at each of its ends. The MIDI specification uses only 2 of the five pins with pins 4 and 5 used to conduct MIDI data whilst pin 2 is used to connect the cables shield to the equipment ground. Thus the abovementioned cable would be suitable for MIDI the only assertion being that pins 1 and 3 would not be utilised. [1]
44 - What data is provided by a MIDI THRU connector?
The data provided by a MIDI THRU connector is an exact copy of the information being received from the MIDI port and which is then transmitted out to another MIDI instrument or device that follows in the connected MIDI chain. Thus, the MIDI thru port is the link between MIDI devices and instruments. [1]
45 - What would you be most likely to use the MIDI OUT connector for on a keyboardless MIDI sound module
I would most likely use the MIDI out connector on a keyboardless MIDI sound module for connection to System exclusive bulk data dumps.
46 - You are using a MIDI sequencer to record many complex tracks to be played on a MIDI system where several modules are chained together, THRU to IN. What might happen if you use Pitch Bend or Control Change messages excessively?
In the abovementioned situation, if Pitch Bend or Control Change messages are used excessively this can cause a data overload in the system thus latency may occur. ??
47 - Some MIDI equipment processes data from the IN connector before sending it to the THRU. What effect does this have on timing?
Latency would be resultant in the abovementioned situation.
48 - You are mixing MTC on the same cable as musical data. How might this affect the timing of notes?
If MTC – MIDI Time Code is being mixed on the same cable as musical data this will adversely affect the timing as MTC will and always have top priority over all messages, thus the timing may become unstable and there will most likely be a lag.
49 - You have connected a keyboard with 32 note polyphony to a sequencer and you find that it is only capable of 16 note polyphony when played manually. If the keyboard can give the full 32 notes when disconnected from the sequencer what has happened?
50 - You are recording a melody into a sequencer. The melody contains a complex series of notes and pitch bend movements and you can’t get both the notes and pitch bend moves right simultaneously. What should you do?
In the situation mentioned above the most likely situation could be to first record the melodies on the sequencer then use the Control Change setting to capture modulation and pitch data then combine the two sources. ?????????
51 - You have recorded a piano sound into a sequencer performed by a keyboard player who tends to use the sustain pedal a lot. What problem might you find if you record another piano part on the same MIDI channel?
52 - You have sampled a four bar drum loop and you trigger it from the sequencer on the first beat of bar 1. You also trigger it on the first beat of bar 5. What will happen if you play the sequence from bar 3?
Reference:
[1] MODERN RECORDING TECHNIQUES – DAVID MYLES HUBER, ROBERT RUNSTEIN
[2] WWW.SWEETWATER.COM
[3] http://www.users.globalnet.co.uk/~bunce/index.htm#contents |
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Sat Apr 30, 2005 3:52 pm |
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JohnA
Joined: 20 Jan 2005
Posts: 28
Location: Mid Glamorgan, UK |
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Audio Course
AUMT03
Week 8
MIDI
JohnA (mixindown)
01 - What does MIDI stand for?
Midi stands for Musical Instrument Digital Interface.
02 - Is MIDI a serial or parallel data flow?
Midi is a serial data flow, data is transmitted one instruction after another.
03 - How does MIDI data contain timing information?
Midi data contains timing information by using a Midi System Message called Midi Clock. Midi clock is related to the tempo of the “sending” device. It provides 96 clocks for each 4 beat bar of music. You could sync a drum machine to a sequencer using Midi Clock and use either one to act as master timing source. The slave (the machine being controlled) has to be set to “external MIDI sync”. This means that it will follow the tempo generated by the master device.
04 - What are the advantages and disadvantages of MIDI over digital audio?
Advantages of MIDI over audio are:
a. Storage of MIDI data is much smaller than storage of digital audio (the files are far smaller).
b. You can store your performance in MIDI and play back another instrument using the same original performance.
c. Editing MIDI data is far quicker and easier than editing digital audio.
Disadvantages of MIDI over audio:
a. It does not extend to voice control.
05 - Briefly describe the General MIDI standard
The GM (General MIDI) standard defines that each manufacturer must insure that their sounds provide an acceptable representation of song data written for General MIDI.
These sounds are grouped into 16 families and in each family there are 8 specific instruments. These include piano, guitar, brass etc. GM also states that a minimum of either 24 fully dynamically allocated voices are available simultaneously for both melodic and percussive sounds, or 16 dynamically allocated voices are available for melody plus 8 for percussion. All voices respond to velocity. All 16 MIDI channels must be supported.
GM also stipulates that drum and percussion sounds must be on MIDI channel 10 and each sound must be placed on a specific key on the keyboard.
06 - What other standards have evolved from GM?
Other standards that have evolved from GM (general MIDI), Roland GM2, GS, GML (GM Lite) and Yamaha XG.
07 - What is the data rate of MIDI information in kbits?
The MIDI data stream is a unidirectional asynchronous bit stream at 31.25 Kbits/sec.
08 - What is a UART?
The Universal Asynchronous Receiver/Transmitter (UART) controller is the key component of the serial communications subsystem of a computer. The UART (which is a computer chip) takes bytes of data and transmits the individual bits in a sequential fashion. At the destination, a second UART re-assembles the bits into complete bytes.
The fundamental function of a MIDI interface for the PC is to convert parallel data bytes from the PC data bus into the serial MIDI data format and vice versa (a UART function). However, "smart" MIDI interfaces may provide a number of more sophisticated functions, such as generation of MIDI timing data, MIDI data buffering, MIDI message filtering, synchronization to external tape machines, and more.
09 - What purpose does a MIDI Thru connection serve?
On a synth, information received at the MIDI IN can be transmitted back out to the MIDI THRU connector. Several MIDI sound modules can be daisy-chained by connecting the MIDI THRU output of one device to the MIDI IN connector of the next device downstream in the chain. This allows the user to control a number of different sound modules from one controller such as a MIDI keyboard.
10 - What is daisy-chaining in terms of MIDI connectivity, and what are its
disadvantages?
Daisy-chaining is achieved by connecting a MIDI controller such as a MIDI keyboard to a number of MIDI sound modules. The keyboard then controls the sounds in these modules. Example of a two module daisy-chain: Device 1 is a MIDI keyboard, devices 2 & 3 are MIDI sound modules.
Connect device 1 MIDI OUT to device 2 MIDI IN, device 2 MIDI THRU to device 3 MIDI IN. This will pass the MIDI data generated by device 1 THRU device 2 to device 3. The difference between the MIDI OUT and MIDI THRU ports is that data coming from the OUT port has been generated on the device containing the OUT port. Data coming out of a devices THRU port is an exact duplicate of data received at the IN port.
The main disadvantage to the daisy chain setup is its inability to pass data quickly enough. As with most chained devices in a serial chain, the last device in the chain is of course the last to receive the data. This means that in a chain that is too long (containing around 4 or more MIDI devices), the data is delayed as it passed from one device to the next. This delay means that notes reaching the farthest out device in the chain are played behind the beat. This is obviously a disadvantage when recording. The reason this happens is that MIDI data is transmitted serially, meaning one bit after the other at a fixed rate of 31,250 bits per second. That is slower then your typical dial-up modem. A midi connection can choke if the data stream gets too heavy.
The MIDI signal deteriorates slightly as it passes through each successive instrument. After passing through three or four instruments, the MIDI messages may start to become unreliable, resulting in notes which stick on or refuse to play at all.
11 - What are the advantages of multi-port MIDI interfaces?
A multi port MIDI interface allows the data to be transmitted to many synths or other pieces of gear at once without delay. The advantages to having a multi-port MIDI interface set-up is that it has at least two MIDI output sockets (pro set-ups may have up to  and each of these has its own set of 16 MIDI channels. Each of these ports can transmit on all 16 MIDI channels at once. The MIDI interface is fed data from either a controller or the sequencer and this is distributed to all the synths hooked to the out ports of the device. Multi-port MIDI interfaces have the advantage of spreading data over the different ports to avoid data bottleneck problems (caused by too much data going over a system with just one MIDI port. The larger pro-type interfaces can be programmed to serve many different functions and also generally have onboard sync and the ability to generate their own MIDI clock or SMPTE timing.
12 - What is a MIDI channel?
There are 16 MIDI channels on a MIDI port. A MIDI channel is one of these 16 channels. Each MIDI channel is capable of using a single instrument or patch at a time.
MIDI channels are not physically separated, i.e., they are not transmitted on separate strands of wire. Rather, the different channel numbers (1-16) are contained in the beginning of the MIDI message, and determine whether an instrument or device will respond to that message. In this way, messages can be directed to certain devices, while other devices, which might also be receiving the information, will ignore them. Most new instruments can be programmed to respond to any one or even all MIDI channels.
13 - With reference to the MIDI interface and the MIDI specification explain why MIDI systems can only have 16 channels?
The specification of a MIDI port allows it to send and receive on up to 16 MIDI channels. The system is set up so that MIDI information sent and received is encoded with a channel number. This number is found in the lower four bits of the status byte. A value of 0 corresponds to MIDI channel 1, a value of 1 corresponds to MIDI channel 2, and so on up to MIDI channel 16 (with a value of 15).
14 - What channel must be used for drums/percussion under the GM standard?
The GM standard specifies that Key-based percussion is always on MIDI channel 10.
15 - What does Omni mean in terms of the reception of MIDI information on discrete channels?
When Omni mode is Off, the synthesizer will only respond to MIDI messages on one Channel.
16 - What is the status byte and what information will it typically include?
Each midi command has a sequence of bytes and the first byte is the status byte. The status byte tells the connected midi device what function to perform. Within the status byte is the midi channel number. Status bytes start with a 1 (whereas data bytes start with a 0). Status bytes always have a value of 128 or more.
17 - What information is typically found in the data byte?
A data byte carries the actual data that is sent to the instrument. MIDI data bytes are in the range from 0 to 127. They are always associated with a MIDI command byte. The meaning of a MIDI data byte is determined by is position after a particular MIDI command byte. For example, a note-on command byte is followed by two MIDI data bytes. The first byte tells you which key is being turned on, and the next byte tells you how hard the key was pressed on the synthesizer keyboard (the attack velocity).
18 - Describe the three bytes of a MIDI note-on message.
The three bytes of a MIDI note-on message are
Byte Number 1: Note On
Byte Number 2: Specifies the pitch of the note
Byte Number 3: Specifies the velocity of the note
19 - What are control change (cc) messages?
Control Change Messages
Control Change messages are MIDI messages for pedals, levers and knobs - found on keyboards and other MIDI devices. The most common Control Change message is Modulation, which is sent when you move the Modulation wheel on a synth.Control Change messages are also called simply controllers, which can lead to some confusion, since the same term is used for a physical device used for sending MIDI data!
20 - What is the purpose of system exclusive (sysex) messages?
The purpose of a system exclusive message (sysex) is a way of allowing a manufacturer to send any kind of data to a device. Sysex, or system exclusive data is a MIDI message that is specific to one device. It could be a patch change or all of the data needed to define a bank of sounds in a synth. Sysex data is sent to a particular instrument by the first part of the MIDI message's header. The header includes the manufacturers ID and the devices ID. If there is two or more of the same device they will both respond to the messages; to prevent this form happening change one unit's device ID.
21 - What is the difference between channel and system messages?
Channel messages are those which apply to a specific Channel, and the Channel number is included in the status byte for these messages. System messages are not Channel specific, and no Channel number is indicated in their status bytes.
22 - What MIDI note number is the musical note C3 on a MIDI keyboard?
C3 on a MIDI keyboard is MIDI note number 60.
23 - How may velocity values are there?
There are 128 velocity values (0 to 127).
24 - What is 'running status'?
Running status is used to speed up MIDI transmission. If, for example, a three note chord was played on a keyboard, the same “note on” status message would be repeated at the start of each note. This identical status message is being sent three times in this example. With Running Status, an instrument will only send a status byte when the type of message changes. This way, the status message is sent only once instead of three times. This means less information is sent which means the MIDI transmission will be faster.
25 - In running status, why is a velocity value of 0 treated as a note off message?
Velocity value of 0 is treated as a note off message in running status to enhance the effectiveness of reducing traffic thus speeding up the MIDI messaging sent and received.
26 - What is the purpose of the 'Local' setting on MIDI devices?
There are many MIDI keyboard instruments include both the keyboard controller and the MIDI sound module functions within the same unit. In these units there is an internal link between the keyboard and the sound module which may be enabled or disabled by setting the "local control" function of the instrument to ON or OFF respectively. By setting the Local Off function, the MIDI keyboard can control external sound modules.
27 - What are system realtime messages?
The MIDI System Real Time messages are used to synchronize all of the MIDI clock-based equipment within a system, such as sequencers and drum machines. Most of the System Real Time messages are normally ignored by keyboard instruments and synthesizers. To help ensure accurate timing, System Real Time messages are given priority over other messages, and these single-byte messages may occur anywhere in the data stream (a Real Time message may appear between the status byte and data byte of some other MIDI message). They are the Timing Clock, Start, Continue, Stop, Active Sensing, and the System Reset message. The Timing Clock message is the master clock which sets the tempo for playback of a sequence. The Timing Clock message is sent 24 times per quarter note. The Start, Continue, and Stop messages are used to control playback of the sequence.
28 - What are Song position pointers (SPPs)?
Song Position Pointers are used by the MIDI Sync/Clock synchronisation protocol to tell a slave device the timing position of the master. This way, the slave knows at any given moment where in the song the master is and can go to that position.
29 - Briefly describe the MIDI TimeCode (MTC) protocol.
MIDI Time Code (MTC) is a sub-protocol within MIDI, and is used to keep 2 devices that control some sort of timed performance (ie, maybe a sequencer and a video deck or tape recorder) in sync. MTC messages are an alternative to using MIDI Clocks and Song Position Pointer messages. MTC is essentially SMPTE mutated for transmission over MIDI. SMPTE timing is referenced from an absolute "time of day". On the other hand, MIDI Clocks and Song Position Pointer are based upon musical beats from the start of a song, played at a specific Tempo. For many (non-musical) cues, it's easier for humans to reference time in some absolute way rather than based upon musical beats at a certain tempo.
30 - Briefly describe the MIDI Machine Control (MMC) protocol.
Midi machine control(MMC) allows the sequencer to chase the audio recorder OR for the audio recorder to chase the sequencer. Midi Machine Control uses MTC to keep things locked up to a very tight degree of resolution.
The sequencer transmits MIDI Machine Control messages via MIDI to the tape recorder, which is equipped with an "intelligent" MIDI interface. These MIDI Machine control messages "tell" the tape recorder to Rewind, fast forward, wind to a certain position. When you hit play on the sequencer, it will first tell the tape recorder to wind to the position from where playback is to commence. When the tape recorder reaches this position, it starts playing the tape back. This, in turn, will make the sequencer receive time code, to which it can then sync. In this system, the transport controls in the sequencer effectively control both the sequencer itself and the tape recorder.
31 - Why are modulation wheels often found on MIDI keyboards?
The modulation wheel or Mod wheel is a continuous controller and is used to add expression on a keyboard. The mod wheel allows the player of the keyboard to add such things as pitch bend as well as vibrato to a sound.
32 - Define the term polyphony.
The polyphony of a sound generator refers to its ability to play more than one note at a time. Polyphony is generally measured or specified as a number of notes or voices. Most of the early music synthesizers were monophonic, meaning that they could only play one note at a time. If you pressed five keys simultaneously on the keyboard of a monophonic synthesizer, you would only hear one note. Pressing five keys on the keyboard of a synthesizer which was polyphonic with four voices of polyphony would, in general, produce four notes. If the keyboard had more voices (many modern sound modules have 16, 24, or 32 note polyphony), then you would hear all five of the notes.
33 - Define the term multi-timbral
A synthesizer or sound generator is said to be multitimbral if it is capable of producing two or more different instrument sounds simultaneously. If a synthesizer can play five notes simultaneously, and it can produce a piano sound and an acoustic bass sound at the same time, then it is multitimbral. With enough notes of polyphony and "parts" (multitimbral) a single synthesizer could produce the entire sound of a band or orchestra.
34 - What is aftertouch?
Some MIDI keyboard instruments have the ability to sense the amount of pressure which is being applied to the keys while they are depressed. This pressure information, commonly called "aftertouch", may be used to control some aspects of the sound produced by the synthesizer (vibrato, for example). If the keyboard has a pressure sensor for each key, then the resulting "polyphonic aftertouch" information would be sent in the form of Polyphonic Key Pressure messages. These messages include separate data bytes for key number and pressure amount. Channel aftertouch information is sent using the Channel Pressure message, which needs only one data byte to specify the pressure value.
35 - What features do mixing consoles offer that can be controlled by MIDI?
Mixing consoles controlled via MIDI offer functions such as recalling scene memories via message changes, sysex messages and MMC.
36 - How do MIDI messages such as modulation, expression attempt to recreate the nuances of 'real instruments'?
Within MIDI messages you can assign different MIDI values. These values are a way for MIDI to convey different degrees of expression, the higher the value in for example, pitch bend, the more the note will appear to bend. This could imitate the bending of a stringed instrument. The same rule would apply to modulation, vibrato etc.
37 - List eight types of MIDI message which are either System Common or System Real Time. (Hint: these are messages that are NOT identified by MIDI Channel numbers).
System common messages include:
MIDI Timing Code
Song Position Pointer
Song Select
Tune Request
System real time messages include:
Timing Clock
Start Sequence
Continue Sequence
Stop Sequence
38 - List four synchronisation strategies used in MIDI music production that can be used, with appropriate equipment, to synchronise a MIDI sequencer and a multitrack audio recorder. Expand any abbreviations.
MTC (MIDI Time Code)
MMC (MIDI Machine Code)
MIDI Clock
SMPTE (The Society of Motion picture and Television Engineers)
39 - MIDI timecode quarter-frame, song position pointer, song select, tune request and end of exclusive are all what type of MIDI message?
The above are all types of MIDI system messages.
40 - What does the first bit of each byte of a MIDI message signify?
The first bit of each byte of a MIDI message signifies whether it is a system or data byte.
A system byte is defined by a 1, whereas a data byte is defined by a 0.
41 - Explain the relationship of sequencer tracks, MIDI channels and synthesiser voices.
From a master keyboard the user would set the MIDI channel. The same channel would be set on the receiving synthesiser to produce the voice when the keyboard is played. The MIDI information would then be recorded on the same MIDI channel on the sequencer. This would enable the sound to be recorded then played back by the sequencer.
42 - In a MIDI set up using a MIDI keyboard controller and a computer sequencer what methods may you be able to use to physically input MIDI control data? Give three.
Three methods of physically imputting MIDI control data into a sequencer would include:
a. using the modulation wheel.
b. Using the pitchbend wheel.
c. Using an expression pedal.
43 - You have a cable with a 5-pin DIN connector at each end. If it is suitable for copying a recording from one cassette deck to another, would it be suitable for MIDI?
No.
44 - What data is provided by a MIDI THRU connector?
The data provided by the MIDI THRU connector is a copy of the data received at the midi In connector of the same device.
45 - What would you be most likely to use the MIDI OUT connector for on a keyboardless MIDI sound module
You would most likely use the MIDI OUT connector on a keyboardless MIDI sound module to store program data on an external MIDI storage device or sequencer.
46 - You are using a MIDI sequencer to record many complex tracks to be played on a MIDI system where several modules are chained together, THRU to IN. What might happen if you use Pitch Bend or Control Change messages excessively?
Using control change messages excessively on the above system would cause latency delay due to the amount of information required for a serial system such as MIDI.
47 - Some MIDI equipment processes data from the IN connector before sending it to the THRU. What effect does this have on timing?
If MIDI equipment processes data from the IN connector before sending it to the THRU MIDI connector, it will delay the information and therefore cause latency problems for the timing.
48 - You are mixing MTC on the same cable as musical data. How might this affect the timing of notes?
When MTC is being mixed on the same cable as musical data, MTC is given priority and so the timing of the notes may not be completely accurate.
49 - You have connected a keyboard with 32 note polyphony to a sequencer and you find that it is only capable of 16 note polyphony when played manually. If the keyboard can give the full 32 notes when disconnected from the sequencer what has happened?
The keyboard is set to Local On and the sequencer is passing the input data to the MIDI out, therefore each note is sounding twice.
50 - You are recording a melody into a sequencer. The melody contains a complex series of notes and pitch bend movements and you can’t get both the notes and pitch bend moves right simultaneously. What should you do?
You could record the notes in first, then play them back and record the pitch bend moves in next.
51 - You have recorded a piano sound into a sequencer performed by a keyboard player who tends to use the sustain pedal a lot. What problem might you find if you record another piano part on the same MIDI channel?
If you record another piano part on the same MIDI channel, the sustain pedal data will affect the new piano part.
52 - You have sampled a four bar drum loop and you trigger it from the sequencer on the first beat of bar 1. You also trigger it on the first beat of bar 5. What will happen if you play the sequence from bar 3?
There will be silence until the first beat of bar 5, from which point, the sample will play.
JohnA
http://www.harmony-central.com/MIDI/Doc/tutorial.html
http://www.soundonsound.com/sos/1995_articles/dec95/midibasics5.html
http://music.northwestern.edu/links/projects/midi/pages/midibnin.html
http://www.planetoftunes.com/sequence/midibasics.html
http://www.midi.org/ |
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Sun May 01, 2005 7:43 am |
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thx1138
Joined: 07 Jan 2005
Posts: 21
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01 - What does MIDI stand for?
MIDI stands for Musical Instrument Digital Interface.
02 - Is MIDI a serial or parallel data flow?
MIDI is serial data flow. It uses what is known as asynchronous serial communication.
03 - How does MIDI data contain timing information?
A group of system messages called the System Real-time Messages control the execution of timed sequences in a MIDI system. A MIDI clock byte is transmitted by the master device 6 times per MIDI beat (equivalent to a musical 16th note). All slave devices lock onto the tempo indicated by the MIDI clock byte.
04 - What are the advantages and disadvantages of MIDI over digital audio?
Advantages:
Doesn't take up much storage space, as MIDI files are very small. Voicing and tempo is easily changeable.
Disadvantages:
It is the recording of musical event data as opposed to recording the musical sounds themselves, so it is reliant on having other devices to actually make the sounds. Without sound generators it is virtually useless.
05 - Briefly describe the General MIDI standard
General MIDI was introduced to standardise some basic elements of sound generator control. A standard mapping of voices to program numbers with a range of up to 128. It also specifies a minimum degree of polyphony.
06 - What other standards have evolved from GM?
GM2, which supports increased polyphony and has an extra percussion channel.
XG (extended general) created by Yamaha and has a greater variety of voices and enhanced effect operation.
GS (general synth) which is a format for sound sources which defines the manner in which multi-timbral sound generating units will respond to MIDI messages.
These are all backward compatible with normal GM.
07 - What is the data rate of MIDI information in kbits?
A maximum of 31.25 kbits per second.
08 - What is a UART?
UART is a device which is a more advanced version of a shift register (a device that converts serial data into parallel form). UART, which stands for Universal Asynchronous Receiver/Transmitter, automatically controls the timing of the serial interface and converts data to and from the parallel form.
09 - What purpose does a MIDI Thru connection serve?
A MIDI Thru connection enables more than one device to be controlled by the same MIDI message. Messages received by the MIDI In are echoed by the MIDI Thru.
10 - What is daisy-chaining in terms of MIDI connectivity, and what are its
disadvantages?
Daisy chaining is when devices are connected to the MIDI Thru of a slave device in a chain so they can be controlled by the same MIDI message. A disadvantage of daisy chaining is possible latency. It takes roughly 1 ms to send a MIDI message, which isn't noticeable, but if a chain of devices is particularly long then this latency will build up.
11 - What are the advantages of multi-port MIDI interfaces?
Multi-port interfaces have a number of independent MIDI Out ports. Each MIDI out can address 16 channels so multi-port interfaces increase the amount of addressable channels multiplied by the amount of ports. It also eliminates the need for daisy chaining (depending on how many MIDI Out ports you actually have).
12 - What is a MIDI channel?
A MIDI channel is a specific channel that certain devices/sound generators are set to respond to. A device will only respond to MIDI messages on a set channel or set number of channels.
13 - With reference to the MIDI interface and the MIDI specification explain why MIDI systems can only have 16 channels?
The first byte in a MIDI message is normally the status byte, which contains information about the channel to which the message applies. 4 bits of the status byte are set aside to indicate the channel number. 4 bits means that 16 different values can represented, as each bit corresponds to 4 binary numbers so with 4 bits there are 16 binary numbers.
14 - What channel must be used for drums/percussion under the GM standard?
The drums/percussion are on channel 10, which is the percussion, channel which has a defined set of note numbers at which particular sounds occur. For example, note number/key 39 = handclap.
GM2 assigns channels 10 and 11 as percussion channels.
15 - What does Omni mean in terms of the reception of MIDI information on discrete channels?
A device set to Omni mode will receive and act upon MIDI signals transmitted on all 16 channels.
16 - What is the status byte and what information will it typically include?
The status byte is one of the two basic types of MIDI message byte, the other being the data byte.
Status bytes always start with a binary 1 to distinguish them from data bytes, which begin with a binary zero (this is known as the most significant byte or MSB).
The status byte contains a binary digit 1 (the MSB), 3 bytes to define the message type, which denotes what type of message is to follow in the data byte (i.e. note on, control change), and 4 bits to define the channel number to which the message applies.
Status byte:
1sssnnn s = message type n = channel number.
17 - What information is typically found in the data byte?
The data byte typically consists of the binary number 0, to distinguish it from a status byte, and the remaining 7 bits carry the message data, such as the note on message, then it would contain the note number and the note velocity.
18 - Describe the three bytes of a MIDI note-on message.
First: Status byte (&9n n = channel number)
Second: Data byte 1 (note number)
Third: Data byte 2 (note velocity)
19 - What are control change (cc) messages?
Controller change messages are information which corresponds with various switches, control wheels and pedals associated with a controlling device.
There are two types of controller message: Continuos type and Switch type.
Continuos type is any variable wheel, slider or lever that has any number of positions. Switch type are controllers that only have two states.
20 - What is the purpose of system exclusive (sysex) messages?
System exclusive messages are ones which are unique to particular manufacturers and sometimes particular instruments that other devices on the same channel will ignore.
Examples of applications of sysex messages:
Sample data dumps (from a sampler to computer and back again for editing purposes)
Voice data dumps (from a synthesiser to a computer for storage and editing of user programmed voices)
21 - What is the difference between channel and system messages?
Channel messages are received by devices set to the targeted channel; the channel information set in the second part of the status byte.
System messages are received by all connected devices regardless of the channels they are set to respond to. System messages contain no channel information in the status byte; instead the second part is used for further identification of the system message.
22 - What MIDI note number is the musical note C3 on a MIDI keyboard?
C3 is note number 60. C-2 is note number 0 and each progressive octave (C-1, C0, C1 etc) the note number increase by 12 up to 127 which is G8 as MIDI messages allow for only 128 notes (0-127).
23 - How may velocity values are there?
There are 128 velocity values as the data byte concerning velocity (data 2) has seven available bits. As each bit is 4 binary digits, 7 multiplied by 4 equals 128. The same applies for the amount of notes MIDI allows.
24 - What is 'running status'?
Running status is a method of reducing the amount of data transmitted over a MIDI interface. It is unnecessary to send the status byte in every MIDI message as once the status byte has been asserted there is no need to send it again for consecutive messages of the same status. Running status is not used at all times for strings of same-status messages and will often only be called upon by an instruments software when the rate of data exceeds a certain point.
25 - In running status, why is a velocity value of 0 treated as a note off message?
In most music, each note on message is almost always followed by a note off message for the same note number.
Changing from note on to note off is a change in status and so it would eliminate the advantages of running status. Instead, note on velocity 0 is used as an equivalent of a note off message because it avoids a change in status during running status.
26 - What is the purpose of the 'Local' setting on MIDI devices?
Local on/off is used to make or break the link between an instruments keyboard and its own sound generators.
If the switch is opened, the link is broken and output from the keyboard goes to the MIDI out while the sound generators are controlled from the MIDI in. In this mode the instrument would act as a separate controller keyboard and sound module.
27 - What are system real-time messages?
System real-time messages are a group of system messages that control the execution of timed sequences in a MIDI system. Often used in conjunction with the song pointer which is when a master device tells devices slaved to it the current position within a sing.
28 - What are Song position pointers (SPPs)?
SPPs are used when the master device needs to tell slave devices where it is in a song.
The SPP represents the position in a song in terms of the number of MIDI beats from the start of a song. It is related to musical time rather than real time so doesn't necessarily represent the number of seconds into the song.
29 - Briefly describe the MIDI TimeCode (MTC) protocol.
MIDI timecode is used widely as a means of synchronising MIDI controlled devices to a real time reference.
30 - Briefly describe the MIDI Machine Control (MMC) protocol.
The MMC protocol is used to remotely control tape machines, VTRs and other studio equipment. It usually runs alongside MIDI timecode and is also in real time.
31 - Why are modulation wheels often found on MIDI keyboards?
The modulation wheel sends continuos type control change messages, the wheel allows real time control of expression such as pitch bend and vibrato. It is used to more accurately emulate a real instrument.
32 - Define the term polyphony.
Polyphony is the ability of an instrument/system to play more than one note at the same time.
33 - Define the term multi-timbral
This is the ability of an instrument/system to play more than one voice or patch at the same time.
34 - What is aftertouch?
Aftertouch is a devices response to when pressure is applied to a key after the note has been struck and when it is being held down or sustained.
There are two types: channel after touch which looks at the keys being held and uses the highest aftertouch value and polyphonic aftertouch, which assigns an aftertouch value to each key that is being held down.
35 - What features do mixing consoles offer that can be controlled by MIDI?
Fader automation, muting, VCA settings, mix synchronisation.
36 - How do MIDI messages such as modulation, expression attempt to recreate the nuances of 'real instruments'?
They attempt to recreate the nuances of real instruments by allowing such features as vibrato and pitch bend.
37 - List eight types of MIDI message which are either System Common or System Real Time. (Hint: these are messages that are NOT identified by MIDI Channel numbers).
System common messages:
Quarter frame, song pointer, song select, tune request.
System real-time messages:
Timing clock, start, continue, stop, active sensing, reset.
38 - List four synchronisation strategies used in MIDI music production that can be used, with appropriate equipment, to synchronise a MIDI sequencer and a multitrack audio recorder. Expand any abbreviations.
MIDI machine control (MMC)
MIDI timecode (MTC)
Song position pointers and the MIDI clock.
SMPTE time code (society of motion picture and telephone engineers)
39 - MIDI timecode quarter-frame, song position pointer, song select, tune request and end of exclusive are all what type of MIDI message?
These are all system common messages.
40 - What does the first bit of each byte of a MIDI message signify?
The first byte of each MIDI message signifies the type of MIDI message. Either status or data byte. The first bit is known as the MSB (most significant byte, a binary 1 denotes that it is a status byte and a binary 0 denotes a data byte.
41 - Explain the relationship of sequencer tracks, MIDI channels and synthesiser voices.
A sequencer has many tracks, each track represents playback of one part/layer of a song, such as a piano part. Each part will typically be given its own channel. Each channel can also apply to a synthesiser voice.
42 - In a MIDI set up using a MIDI keyboard controller and a computer sequencer what methods may you be able to use to physically input MIDI control data? Give three.
Playing the keyboard controller keys.
Moving the modulation wheel.
Moving any switch, pedal, slider on the controller keyboard.
43 - You have a cable with a 5-pin DIN connector at each end. If it is suitable for copying a recording from one cassette deck to another, would it be suitable for MIDI?
No, it is a crossover cable where pin 5 at one end is connected to pin 4 at the other and pin 4 at one end is connected to pin 5 at the other. A lead suitable for copying a recording from one tape deck to another has pin 5 as cassette in and pin 4 as cassette out and they would 'crossover' to send and receive data correctly between 2 tape machines. A MIDI din plug requires pins 5, 4 and 2 to be connected to the same pins at the other end of the cable. Unless a DIN cable follows this convention they will not work with MIDI.
(www.cs.unc.deu/~yakowenk/coco/text/cassette.html)
44 - What data is provided by a MIDI THRU connector?
Whatever data comes in on the MIDI In port is echoed by the MIDI Thru port so that another device can be attached that will also respond to the same MIDI in signals.
45 - What would you be most likely to use the MIDI OUT connector for on a keyboardless MIDI sound module
system exclusive data dumps?
46 - You are using a MIDI sequencer to record many complex tracks to be played on a MIDI system where several modules are chained together, THRU to IN. What might happen if you use Pitch Bend or Control Change messages excessively?
You might experience some latency due to excessive data being sent to all the devices due to the many control change messages.
47 - Some MIDI equipment processes data from the IN connector before sending it to the THRU. What effect does this have on timing?
This could cause latency, even more so if you have many devices chained together that are doing this.
48 - You are mixing MTC on the same cable as musical data. How might this affect the timing of notes?
MTC has priority over note on/off so note timing could be disrupted.
49 - You have connected a keyboard with 32-note polyphony to a sequencer and you find that it is only capable of 16-note polyphony when played manually. If the keyboard can give the full 32 notes when disconnected from the sequencer what has happened?
The sequencer could be sending data back to the keyboard making every note sound twice.
50 - You are recording a melody into a sequencer. The melody contains a complex series of notes and pitch bend movements and you can’t get both the notes and pitch bend moves right simultaneously. What should you do?
Record the melody into the sequencer first and then record the movements of the pitch wheel afterwards.
51 - You have recorded a piano sound into a sequencer performed by a keyboard player who tends to use the sustain pedal a lot. What problem might you find if you record another piano part on the same MIDI channel?
If you record another piano part on the same channel it will also use the same sustain pedal settings as it would be a controller change message specific to that channel.
52 - You have sampled a four bar drum loop and you trigger it from the sequencer on the first beat of bar 1. You also trigger it on the first beat of bar 5. What will happen if you play the sequence from bar 3?
If you play the sequence from bar 3 the sample will not be played until it is triggered again on the first beat of bar 5.
Sound and Recording: An introduction, fourth edition by Fracis Rumsey and Tim McCormick
Music Engineering, second edition by Richard Brice
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AcousticalWeaponsDivision/Alex |
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Sun May 01, 2005 10:20 am |
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chemira
Joined: 03 Jan 2005
Posts: 50
Location: Nova Scotia Canada Eh! |
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Week 8 Music Technology
Lots of lovely MIDI questions this week;
01 - What does MIDI stand for?
Musical Instrument Digital Interface
02 - Is MIDI a serial or parallel data flow?
MIDI uses serial data flow where packets of information stream in one bit at a time. These packets are sent and unloaded in word lengths of 31250 bits per second.
03 - How does MIDI data contain timing information?
Timing information for MIDI is sent within the word length in the means of MIDI Clock Data. This timing data uses 96 ticks per whole note to schedule the timing of events.
04 - What are the advantages and disadvantages of MIDI over digital audio?
MIDI possesses an advantage over Digital audio in the sense that the size of a similar segment of digital audio will be larger than a MIDI file with the triggered samples. The use of repeating loops or sound fonts with triggering information makes the files smaller. A MIDI file uses the host playback devices wave tables to play back the sequenced MIDI file. The disadvantage is that the Playback host may not have a high quality wave table rendering poor quality sound.
05 - Briefly describe the General MIDI standard
General MIDI standard has 128 instruments and arranges these families of instruments into 16 groups. Program changes are standardized among General MIDI along with pitch, volume, panning and other effect. This allows the arranger to create program changes that should translate suitable over a wide range of host playback devices. Quote “General MIDI is an addition to the original MIDI specification. It follows a standard that assigns 128 instrument sounds that are assigned to specific numbers. There are sixteen specific families or types of instruments and eight instruments within each group. A separate group of percussion sounds is usually available on MIDI channel ten, and they are assigned to specific notes on a MIDI keyboard” unquote. http://music.northwestern.edu/links/projects/midi/pages/genmidi.html
06 - What other standards have evolved from GM?
Revisions on the General MIDI Standard are GM2 increase the number of sounds available, GS from Roland refining how the instrument with a multi timbral sound responds to MIDI messages and XG from Yamaha which also refines the available features with their line of compatible keyboards are all standards derived from GM.
07 - What is the data rate of MIDI information in kbits?
The data rate of MIDI is 31.5Kbits per second or more accurately 31250 bits.
08 - What is a UART?
Universal Asynchronous Receiver/Transmitter is a component that manages the reception and transmission of serial data from inside to outside a computer.
09 - What purpose does a MIDI Thru connection serve?
MIDI Thru connection allows a copy of the Data transmitted into a MIDI device to the next MIDI device allowing the two devices to share information. This will allow timing and sequencing to be controlled with accuracy and a minimum of delay.
10 - What is daisy-chaining in terms of MIDI connectivity, and what are its
disadvantages?
Daisy Chaining is the connection setup where the through outputs of several modules are connected in series from one module to the next. This still has a delay incurred at each connection so as the modules are added so is the delay.
11 - What are the advantages of multi-port MIDI interfaces?
Multi port MIDI interfaces allow more synchronized timing between MIDI modules since the DATA timing is sent in Parallel to each MIDI Module so they all receive the Timing Data at the same time..
12 - What is a MIDI channel?
A MIDI channel is a stream of DATA that is used to control a specific instrument or part. There are 16 MIDI channels transmitted on a MIDI Cable. This is actually a division of the data transmitted in the wordlength.
13 - With reference to the MIDI interface and the MIDI specification explain why MIDI systems can only have 16 channels?
The wordlength in MIDI specifies the channel possibilities in the DATA stream. This wordlength is standard.Quote” All MIDI devices receive MIDI information at the MIDI In port. All MIDI channel message information has an identification of a specific MIDI channel. The second nibble of a MIDI byte has sixteen possibilities that identify the MIDI channel.” Unquote
14 - What channel must be used for drums/percussion under the GM standard?
Channel 10 is the GM standard channel for drums and percussion.
15 - What does Omni mean in terms of the reception of MIDI information on discrete channels?
Omni Mode refers to the module responding to all of the messages that it receives. This will make the module play all of the tracks that it receives from all of the instruments selected.
16 - What is the status byte and what information will it typically include?
The status byte is the first MIDI message that is received and it will tell the MIDI device what function to perform such as note on/off or similar functions.
17 - What information is typically found in the data byte?
The Data Byte will contain information regarding the note and the note velocity.
18 - Describe the three bytes of a MIDI note-on message.
First byte is the status byte selecting channel, second byte selects the note and the third byte controls the velocity.
19 - What are control change (cc) messages?
Control change messages are bank select, modulation wheel, breath controller, foot controller, volume balance, pan, expression, effects which allow modification on the triggered sound after it has been triggered.
20 - What is the purpose of system exclusive (sysex) messages?
System Exclusive messages are used to control patch parameters for an individual format of keyboard manufacturer. The manufacturers are awarded unique identifiers and their ID byte will specify that only it’s system will be affected by the message.
21 - What is the difference between channel and system messages?
Channel messages will affect and control the devices that are on the individually specified channel. The System message will only affect a device on that channel with the same ID byte.
22 - What MIDI note number is the musical note C3 on a MIDI keyboard?
Note C3 in MIDI also Known as note 60 is middle C on the Keyboard.
23 - How may velocity values are there?
There are 127 velocity values assigned to MIDI.
24 - What is 'running status'?
This term running status in MIDI refers to the status byte not being required in the MIDI message as long as the status byte is the same as the last status byte.
25 - In running status, why is a velocity value of 0 treated as a note off message?
In running status mode the velocity value of 0 would create no volume so it will be interpreted as off.
26 - What is the purpose of the 'Local' setting on MIDI devices?
Local Settings in MIDI Keyboards refers to weather or not the keyboard will sound it’s patch within the keyboard or if the keyboard will trigger through a sequencer and then back to the keyboard as an echo.
27 - What are system realtime messages?
System realtime messages are used to synchronize several MIDI devices so that the devices will send and receive their messages at an expected time. This enable better tracking for playback and triggering of MIDI devices on the same network.
28 - What are Song position pointers (SPPs)?
Song Position Pointers are reference points that indicate where or how many beats the specific point is into the song or sequence.
29 - Briefly describe the MIDI TimeCode (MTC) protocol.
MIDI Timecode embeds timing information in hours, minutes, seconds and frame number
similar to SMTE. This allows synchronization between two or more MIDI devices. This is to ensure that the timing of the devices during playback or in time between triggering of devices is synchronized.
30 - Briefly describe the MIDI Machine Control (MMC) protocol.
MIDI Machine Control is a MIDI message that is used to trigger the controls of Tape machines or similar devices. Both the triggering and the controlled devices require this protocol and are connected via a standard MIDI cable.
31 - Why are modulation wheels often found on MIDI keyboards?
Modulation Wheels will control a LFO to create vibrato or modulation effects by CC messages. The control wheel can also be assigned to any other variable event message such as real time volume or panning.
32 - Define the term polyphony.
Polyphony is a keyboards ability to play more than one note at a time. The number or capability of the keyboard will be expressed as for example 64 note polyphony or 128 note polyphony. This will mean that 64 separate notes or 128 separate notes can be played or triggered at the same time.
33 - Define the term multi-timbral
Multi timbral referees to a keyboards ability to trigger several different sounds or voices at the same time or during playback. A keyboard may be able to playback drums, bass and piano at the same time.
34 - What is aftertouch?
Aftertouch is the ability for a keyboard with sensing strips under the keys to transmit the signal strength to a VCA VCF or LFO. This will determine the Sustain (VCA) the spectral content (VCF) or Vibrato (LFO) that would continue as the key is still held down and it’s depth will be determined by how much pressure is applied to the key.
35 - What features do mixing consoles offer that can be controlled by MIDI?
MIDI Controlled mixers can utilize Fader automation, mute controls or any number of realtime effects can be controlled. Any Mixer that has MIDI control can be synchronized to a Sequencer via MTC for playback automation or the Mixer can be remotely controlled for realtime remote control of faders, mutes or effects.
36 - How do MIDI messages such as modulation, expression attempt to recreate the nuances of 'real instruments'?
Modulation can create vibrato and volume swells that can be programmed to create changes in the performance in varying degrees. These changes can be modified with aftertouch, or by the modulation wheel.
37 - List eight types of MIDI message which are either System Common or System Real Time. (Hint: these are messages that are NOT identified by MIDI Channel numbers).
Eight or More MIDI messages that are system common or system real time are MIDI Time Code MTC, Song position pointer, song select, Tune request, End of exclusive (EOX), Timing Clock, Start, Continue, Stop, Active Sense and System reset.
38 - List four synchronization strategies used in MIDI music production that can be used, with appropriate equipment, to synchronise a MIDI sequencer and a multitrack audio recorder. Expand any abbreviations.
Four synchronization strategies for MIDI are 1) MIDI time Code or MTC, 2) MIDI Machine Code or MMC 3) Frequency Shift Key or FSK and lastly 4) Society of Motion Picture and Television Engineers known as SMPTE.
39 - MIDI timecode quarter-frame, song position pointer, song select, tune request and end of exclusive are all what type of MIDI message?
40 - What does the first bit of each byte of a MIDI message signify?
The first bit of a status byte is a 1 to tell the receiving unit that a new message coming in.
41 - Explain the relationship of sequencer tracks, MIDI channels and synthesizer voices.
42 - In a MIDI set up using a MIDI keyboard controller and a computer sequencer what methods may you be able to use to physically input MIDI control data? Give three.
The keyboard, The MIDI controller or a mouse could be used to input MIDI control data.
Sequencing
43 - You have a cable with a 5-pin DIN connector at each end. If it is suitable for copying a recording from one cassette deck to another, would it be suitable for MIDI?
Yes the audio spec twisted pair could also be used for MIDI.
44 - What data is provided by a MIDI THRU connector?
The Thru connector will forward a direct copy of the information received at the MIDI in connector.
45 - What would you be most likely to use the MIDI OUT connector for on a keyboardless MIDI sound module
46 - You are using a MIDI sequencer to record many complex tracks to be played on a MIDI system where several modules are chained together, THRU to IN. What might happen if you use Pitch Bend or Control Change messages excessively?
The More program change data that is increased during an excessive amount of CC messages would cause latency.
47 - Some MIDI equipment processes data from the IN connector before sending it to the THRU. What effect does this have on timing?
This will also cause latency as the data is processed and then subsequently sent to the next device via the through output.
48 - You are mixing MTC on the same cable as musical data. How might this affect the timing of notes?
Since MTC is the priority data on the cable the accuracy of the placement of the notes will be affected.
49 - You have connected a keyboard with 32 note polyphony to a sequencer and you find that it is only capable of 16 note polyphony when played manually. If the keyboard can give the full 32 notes when disconnected from the sequencer what has happened?
50 - You are recording a melody into a sequencer. The melody contains a complex series of notes and pitch bend movements and you can’t get both the notes and pitch bend moves right simultaneously. What should you do?
51 - You have recorded a piano sound into a sequencer performed by a keyboard player who tends to use the sustain pedal a lot. What problem might you find if you record another piano part on the same MIDI channel?
52 - You have sampled a four bar drum loop and you trigger it from the sequencer on the first beat of bar 1. You also trigger it on the first beat of bar 5. What will happen if you play the sequence from bar 3?
http://jedi.ks.uiuc.edu/~johns/links/music/gm.htm
http://www.midi.org/about-midi/gm/gm2_spec.shtml
http://www.roland.com/worldwide/stories/about-gm-gs.html
http://www.thewhippinpost.co.uk/midi/xg/xg-midi.htm
http://www.archivemag.co.uk/gloss/U.html
http://www.borg.com/~jglatt/tutr/connect.htm#q11
http://www.midi.org/about-midi/table3.shtml
http://www.soundonsound.com/sos/1995_articles/may95/homestudio3.html
http://www.users.globalnet.co.uk/~bunce/midi_2.htm
http://www.earlevel.com/MIDI/MIDI%20Overview.html
http://www.recordingwebsite.com/articles/midi2.php
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Sun May 01, 2005 11:28 am |
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hoaxwagon
Joined: 28 Feb 2005
Posts: 27
Location: Boulder Creek, CA USA |
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week 8 MT hoaxwagon 
01 - What does MIDI stand for?
Musical instrument digital interface
02 - Is MIDI a serial or parallel data flow?
Serial
03 - How does MIDI data contain timing information?
Clock messages (system real time meesages) are sent at the rate of 6 per semiquaver
(a semiquaver = sixteenth note ).
Its duration depends on the speed ,tempo, of the music. This is in contrast with timecode, SMPTE, EBU, where the timing information relates to real time (seconds, minutes, hours).
04 - What are the advantages and disadvantages of MIDI over digital audio?
When you change the tempo of the MIDI sequencer's playback, it doesn't alter the pitch nor the timbre of the sound. So, a sequencer offers complete control of tempo independent of pitch or timbre changes. MIDI sequencers make it easy to transpose musical parts to other key signatures, mute or solo individual parts, reroute musical parts to play upon various sound modules, and make many other changes in timbre, volume, panning, effects levels, etc to individual musical parts. The MIDI sequencer can correct any mistakes recorded into it more easily than tape or digital recording. With MIDI, step entering data does not require the ability to play music. Since MIDI controls electronic instruments digital recording is used along with it for acoustic instruments and voices. Digital audio recording offers virtual tracks but requires a lot of hard drive space.
05 - Briefly describe the General MIDI standard
The General MIDI (GM) Specification, published by the International MIDI Association, defines a set of general capabilities for General MIDI Instruments.
06 - What other standards have evolved from GM?
07 - What is the data rate of MIDI information in kbits?
MIDI sends information at a rate of 31,250 bits per second.
08 - What is a UART?
The Universal Asynchronous Receiver/Transmitter controller is the key component of the serial communications subsystem of a computer. The UART takes bytes of data and transmits the individual bits in a sequential fashion. At the destination, a second UART re-assembles the bits into complete bytes.
09 - What purpose does a MIDI Thru connection serve?
To daisy chain MIDI instruments together
10 - What is daisy-chaining in terms of MIDI connectivity, and what are its
disadvantages?
Daisy chaining is connecting 2 or more MIDI instruments together using the MIDI thru jack. The disadvantages are an overloaded MIDI bus and delays if the MIDI thru is processed first instead of being directly coupled to the MIDI in jack.
11 - What are the advantages of multi-port MIDI interfaces?
Devices can be hooked to the computer via USB and not daisy chained together
12 - What is a MIDI channel?
Without them, every instrument would play all the time, and sequencing multiple parts would be impossible. Since all sixteen channels can be transmitted over a single cable, you can connect many instruments to a single source without having to unplug and replug everything just to change sounds.
13 - With reference to the MIDI interface and the MIDI specification explain why MIDI systems can only have 16 channels?
14 - What channel must be used for drums/percussion under the GM standard?
10
15 - What does Omni mean in terms of the reception of MIDI information on discrete channels?
In Omni Off mode, an instrument responds only to information on the single channel to which it is set, which is called an instrument's basic channel.
16 - What is the status byte and what information will it typically include?
STATUS BYTE
The first part of a midi message, which tells the synth or computer what sort of event is about to happen (e.g., 'note on).
17 - What information is typically found in the data byte?
18 - Describe the three bytes of a MIDI note-on message.
Byte 1 is a message byte, byte 2 is note value and byte 3 is note velocity
19 - What are control change (cc) messages?
MIDI Control Change messages are used to control a wide variety of functions in a synthesizer. Control Change messages, like other MIDI channel messages, should only affect the channel number indicated in the status byte. The control change status byte is followed by one data byte indicating the controller number , and a second byte which specifies the control value .
20 - What is the purpose of system exclusive (sysex) messages?
Sending patch parameter information from a MIDI instrument to a computer for storage or editing.
Transmitting the patterns from one drum machine to another, or to a computer.
Transmitting the memory of a digital sampler to a computer for editing or to another sampler.
Sending song data from a stand-alone sequencer to another sequencer or a computer for storage.
Manipulating individual parameters from the front panel of an instrument for use as a remote control by another of the same instrument.
21 - What is the difference between channel and system messages?
22 - What MIDI note number is the musical note C3 on a MIDI keyboard?
60
23 - How may velocity values are there?
128
24 - What is 'running status'?
Running status is simply a clever scheme to maximize the efficiency of MIDI transmission (by removing extraneous Status bytes).
25 - In running status, why is a velocity value of 0 treated as a note off message?
26 - What is the purpose of the 'Local' setting on MIDI devices?
local control means that the midi signal is routed both to the midi out port on the synth and the internal tone generator
27 - What are system realtime messages?
The System Real Time messages are the Timing Clock, Start, Continue, Stop, Active Sensing, and the System Reset message.
28 - What are Song position pointers (SPPs)?
The Song Position Pointer is used to set a sequencer to start playback of a song at some point other than at the beginning.
29 - Briefly describe the MIDI TimeCode (MTC) protocol
MIDI Time Code is used to keep 2 devices in sync. It references time of day not beats in the song .
.
30 - Briefly describe the MIDI Machine Control (MMC) protocol.
MIDI Machine Control is a protocol specifically designed to remotely control hard disk recording systems, and other machines used for record or playback, over a MIDI cable.
31 - Why are modulation wheels often found on MIDI keyboards?
The musical term for modulation is vibrato, an essential element of musical expression. Modulation can be used to create pitch vibrato (frequency modulation), loudness vibrato (amplitude modulation), brightness vibrato (filter modulation), or for some special digital effects on certain instruments.
32 - Define the term polyphony.
The polyphony of a sound generator refers to its ability to play more than one note at a time.
33 - Define the term multi-timbral
A synthesizer or sound generator is said to be multi-timbral if it is capable of producing two or more different instrument sounds simultaneously.. If it can produce a piano sound and an acoustic bass sound at the same time, then it is multi-timbral.
34 - What is aftertouch?
Is a feature found on expensive keyboards that allows a particular key or note to be affected independantly of other notes being played at the same time. This feature is activated by applying pressure to a key while holding it down.
35 -what features do mixing console offer that are controlled by MIDI?
Built in time code reader generator, dynamically controlled automated desk mutes, Transport controls,
locate buttons for jumping to cue points, MIDI faders, snap shots
36 - How do MIDI messages such as modulation, expression attempt to recreate the nuances of 'real instruments'?
In MIDI, modulation usually means applying a vibrato effect to a sound. A pitch bend wheel allows notes to be bent up or down. (Example: a sliding trombone sound.) Pitch bend is a MIDI message.
37 - List eight types of MIDI message which are either System Common or System Real Time. (Hint: these are messages that are NOT identified by MIDI Channel numbers).
Timing Clock, Start, Continue, Stop, Active Sensing, Reset, quarter frame, song pointer, song select, tune request
38 - List four synchronisation strategies used in MIDI music production that can be used, with appropriate equipment, to synchronise a MIDI sequencer and a multitrack audio recorder. Expand any abbreviations.
FSK (Frequency Shift Keying) (Smart FSK is also acceptable)
MIDI Clock pulses and Song Position Pointers
MTC (MIDI Timecode)
SMPTE timecode
EBU timecode
39 - MIDI timecode quarter-frame, song position pointer, song select, tune request and end of exclusive are all what type of MIDI message?
System Common Messages
40 - What does the first bit of each byte of a MIDI message signify?
The first data is the note number. There are 128 possible notes on a MIDI device, numbered 0 to 127 (where Middle C is note number 60). This indicates which note should be played.
41 - Explain the relationship of sequencer tracks, MIDI channels and synthesiser voices.
42 - In a MIDI set up using a MIDI keyboard controller and a computer sequencer what methods may you be able to use to physically input MIDI control data? Give three.
PCI slot, USB port and parallel input?
43 - You have a cable with a 5-pin DIN connector at each end. If it is suitable for copying a recording from one cassette deck to another, would it be suitable for MIDI?
No, The cable for MIDI is used for data messeges not audio signal
44 - What data is provided by a MIDI THRU connector?
45 - What would you be most likely to use the MIDI OUT connector for on a keyboardless MIDI sound module
to send data to a computers sound card
46 - You are using a MIDI sequencer to record many complex tracks to be played on a MIDI system where several modules are chained together, THRU to IN. What might happen if you use Pitch Bend or Control Change messages excessively?
47 - Some MIDI equipment processes data from the IN connector before sending it to the THRU. What effect does this have on timing?
There is a considerable amount of delay when the MIDI thru is processed first.
48 - You are mixing MTC on the same cable as musical data. How might this affect the timing of notes? It doesn’t
49 - You have connected a keyboard with 32 note polyphony to a sequencer and you find that it is only capable of 16 note polyphony when played manually. If the keyboard can give the full 32 notes when disconnected from the sequencer what has happened?
50 - You are recording a melody into a sequencer. The melody contains a complex series of notes and pitch bend movements and you can’t get both the notes and pitch bend moves right simultaneously. What should you do?
51 - You have recorded a piano sound into a sequencer performed by a keyboard player who tends to use the sustain pedal a lot. What problem might you find if you record another piano part on the same MIDI channel?
52 - You have sampled a four bar drum loop and you trigger it from the sequencer on the first beat of bar 1. You also trigger it on the first beat of bar 5. What will happen if you play the sequence from bar 3?
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