ben m
Joined: 15 Sep 2002
Posts: 337
Location: UK |
| Week 8 - MIDI |
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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 Oct 25, 2004 6:37 pm |
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Rico1210
Joined: 03 Aug 2004
Posts: 39
Location: Newcastle, UK |
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Hi,
here are my answers to the questions on MIDI. Found these rather tough, probably more to do with the volume than the content.
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, which transfers bytes one after another. The advantages of this are that only one cable is needed between devices (Although 2 cables are needed to complete the circuit).
03 - How does MIDI data contain timing information?
MIDI data transmits timing information as part of a MIDI message called MIDI Clock data. MIDI Clock data is a series of electronic timing markers that are transmitted through the MIDI lead with the other messages. It enables devices such as drum machines to be synchronised.
04 - What are the advantages and disadvantages of MIDI over digital audio?
The main advantage of MIDI over digital audio is file size. Digital audio occupies around 5 megabytes of memory space, whereas MIDI data for a minute of music may only occupy 5 kilobytes. A disadvantage of MIDI is that it is limited to music only and does not extend to voice.
05 - Briefly describe the General MIDI standard
General MIDI was introduced to standardise the basic elements of control, so that MIDI files could be exchanged between different systems easily. This creates a standard for mapping voices to program numbers to enable a sequence to be replayed on another system, and not sound completely different. General MIDI also states a minimum degree of polyphony, and requires that a sound generator should be able to receive MIDI data on all 16 channels simultaneously.
06 - What other standards have evolved from GM?
Other standards that have evolved from General MIDI include support for percussion sounds in the form of drum kits, and dynamic voice allocation. Dynamic voice allocation requires at least 24 dynamically allocated voices in total, or 16 for melody and 8 for percussion.
07 - What is the data rate of MIDI information in kbits?
The MIDI standard specifies a unidirectional serial interface running at 31.25 kbits. This is the number of bits per second that can be transferred.
08 - What is a UART?
A UART (Universal Asynchronous Receiver/Transmitter) handles the timing of the serial interface and converts data to and from parallel form.
09 - What purpose does a MIDI Thru connection serve?
The MIDI Thru connection is a direct relay of the data that is passed through the IN connection. It is a buffered feed of the input data that has not been processed in any way.
10 - What is daisy-chaining in terms of MIDI connectivity, and what are its
disadvantages?
Daisy-chaining is where multiple MIDI devices are connected together. The Thru socket is used to transmit information from one controller to a number of receivers, without having to have multiple outputs.
11 - What are the advantages of multi-port MIDI interfaces?
Multi-port MIDI interfaces have more than one independent MIDI out ports, each of which enable 16 channels to be used. Therefore a multi-port interface allows more than the usual 16 channels to be used, as the number available will be 16 times the number of ports. Multi-port interfaces allow data received from more than one port to be merged, and allow more than one source to be recorded simultaneously.
12 - What is a MIDI channel?
A MIDI channel is an independent control channel that allows the master device to selectively control MIDI devices. There are 16 MIDI channels numbered 1 to 16, incorporated into a single MIDI connection. This enables 16 seperate devices to be connected and played individually.
13 - With reference to the MIDI interface and the MIDI specification explain why MIDI systems can only have 16 channels?
MIDI systems can only have 16 channels because of the specification of the status byte in a MIDI channel message. The status message contains a 4bit message that relates to the channel number, there are 16 possible values that can be determined from a 4bit message.
14 - What channel must be used for drums/percussion under the GM standard?
Percussion sounds are always allocated to MIDI channel 10 under the General MIDI standard.
15 - What does Omni mean in terms of the reception of MIDI information on discrete channels?
There are two settings of ‘omni’, omni off mode and omni on mode. Omni off mode is where an instrument is set to receive information on a specific channel or channels, and will ignore all other information. Omni on mode is where the instrument is set to receive information on all channels.
16 - What is the status byte and what information will it typically include?
The status byte is the first byte in a MIDI message that contains information about the channel number to which the information applies. The status byte always begins with a 1 to distinguish it from the data bytes, the first half denotes the message type and the second half denotes the channel number. The status byte is there to identify which part of a receiver the message is intended for, as well as what type of message is to follow ie. Note-on, note-off.
17 - What information is typically found in the data byte?
The information in the data byte is the actual message to the instrument. This will contain the following types of information: Note number and velocity for note on/off messages, note number and pressure for polyphonic aftertouch messages, control number and data for control change messages, and program numbers for program change messages.
18 - Describe the three bytes of a MIDI note-on message.
The three bytes of a MIDI note-on message contain a status byte and two data bytes. The two data bytes will contain note number and velocity information. The general format would be as follows [&8n] [Note number] [Velocity].
19 - What are control change (cc) messages?
Control change messages correspond to the various switches, control wheels and pedals associated with a device. There are two types of controller: the switch type which normally only has two states, and the continuous type which corresponds to a variable wheel, slider, pedal or lever that has a number of different positions.
20 - What is the purpose of system exclusive (sysex) messages?
System exclusive (sysex) messages are messages that are only compatible with the manufacturer’s device that is in use. The first data byte after the status byte contains the Manufacturer’s ID to identify the device.
21 - What is the difference between channel and system messages?
Channel messages relate to specific MIDI channels, whereas system messages relate to the system as a whole. The difference between channel and system messages is the format of the status byte. The status byte in a channel message firstly contains the bits to define the message type, then contains bits to define the channel number. The status byte in a system message does not define a channel number; instead the second part of the byte is used for further identification of the system message.
22 - What MIDI note number is the musical note C3 on a MIDI keyboard?
The musical note C3 is MIDI note number 60, on a MIDI keyboard.
23 - How many velocity values are there?
There are 128 possible velocity values, but not all MIDI instruments are able to generate or interpret the velocity byte, in which case they will set it to a value half way between the limits.
24 - What is 'running status'?
Running status is where a MIDI message is transmitted with data bytes only (without a status byte). This is only achievable as long as the previous transmitted message had the same status. A device remembers the last status byte it received, so if no status byte is received with the next message, it assumes that it is dealing with running status. This reduces delay.
25 - In running status, why is a velocity value of 0 treated as a note off message?
In running status, a velocity value of 0 is treated as a note off message because it avoids a change of status during running status, allowing a string of what appear to be note on messages to represent both note on and note off. Changing status from note on to note off using normal MIDI messaging would eliminate the advantages gained by using running status.
26 - What is the purpose of the 'Local' setting on MIDI devices?
The local setting on MIDI devices is used to make or break the link between an instrument's keyboard and its sound generators. If the switch is opened, the link is broken and the output from the keyboard feeds the MIDI out while the sound generators are controlled from the MIDI in.
27 - What are system realtime messages?
System realtime messages are system messages that control the performing of timed sequences in a MIDI system. For instance, the message START (&FA) should result in playback of the sequence from the beginning. STOP (&FC) is used to stop the playback of a song which is running on an instrument.
28 - What are Song position pointers (SPPs)?
A song position pointer (SPP) represents the position in a stored song, in terms of MIDI beats from the start. Song position pointers are messages sent from the master device to inform instruments at which position of the song they should be.
29 - Briefly describe the MIDI TimeCode (MTC) protocol.
MIDI TimeCode is a means of synchronising MIDI-controlled equipment to a real time reference. MIDI TimeCode is a way of transferring longitudinal timecode (LTC) around a MIDI system. Longitudinal TimeCode is a different format to MIDI messaging, therefore the signal must be converted into a MIDI compatible format ie. status byte followed by data bytes
30 - Briefly describe the MIDI Machine Control (MMC) protocol.
MIDI Machine Control protocol uses realtime SysEx messages for controlling tape machines and other studio equipment. MMC can be used at a number of levels of complexity, and control is possible in both closed and open loop modes. For example, an audio tape recorder can be connected to one port on a mutli-port MIDI interface to control commands such as ‘Record’, ‘Play’, ‘Stop’ and ‘Rewind’.
31 - Why are modulation wheels often found on MIDI keyboards?
Modulation wheels are often found on a MIDI keyboard as they enable the use of control change(CC) messages to modulate a signal in real time.
32 - Define the term polyphony.
Polyphony is where a number of notes may be produced simultaneously. The opposite of polyphonic is monophonic, where only one note may be played at any one time. Polyphony has recently stretched to mobile phone technology, where you can hear those annoying ringtones that play lots of notes at the same time.
33 - Define the term multi-timbral
Multi-timbral is where a device can play a number of different timbres(voices) simultaneously. For instance, a keyboard may be able to play piano sounds along side guitar sounds and brass sounds simultaneously.
34 - What is aftertouch?
Aftertouch is defined as 'channel pressure'. it measures the pressure placed on a key after it is fully depressed. Aftertouch can be used to alter the volume, pitch, or timbre of the sound in real time.
35 - What features do mixing consoles offer that can be controlled by MIDI?
The features offered by mixing consoles that can be controlled by MIDI are: mute automation, VCA control, stops and starts(including fader start), and automix synchronization.
36 - How do MIDI messages such as modulation, expression attempt to recreate the nuances of 'real instruments'?
Volume control messages are used in MIDI channels as a percentage, to attempt to recreate expression of real instruments. Individual channels can be given an initial volume value, which is then controlled by messages that create crescendos and decrescendos which do not alter the relative balance between instruments. Modulation is achieved by pitch bend or by adding vibrato.
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, quarter frame, song pointer, tune request, song select, active sensing, start, stop. All are either System Common or System Real Time messages.
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 TimeCode is a MIDI interpretation of the traditional SMPTE (Society of Motion Picture and Television Engineers) protocol.
MIDI Clock and SPPs - Song Position Pointer represents the position in a stored song, in terms of MIDI beats from the start.
SMPTE - Society of Motion Picture and Television Engineers is based on real time measured in hours, minutes and seconds.
FSK - Frequency Shift Keying is a system which records a series of electronic tones. It is used to connect drum machines together with an audio recorder.
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. Either System Exclusive or System Common.
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 if it is a status byte or a data byte. A status byte always begins with a binary 1, a data byte always begins with a 0.
41 - Explain the relationship of sequencer tracks, MIDI channels and synthesiser voices.
An individual MIDI connection is split into 16 channels. Each of these individual channels can use a separate synthesizer voice which can be captured by a sequencer. The sequencer would then play the parts back together through the synthesizer. Each part would be played on a different MIDI Channel, and the sound module would be set to receive different channels, and play the different 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.
Methods for physical input of MIDI control data include pressing the keys on the keyboard, moving the pitch bend wheel, or drawing in the data using the computers mouse.
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?
A 5-pin DIN connector suitable for copying a recording from one cassette deck to another would not be suitable for use as a MIDI lead. A MIDI cable requires corresponding pin numbers connected at each end ie: pin 4 to pin 4, pin 2 to pin 2 and pin 5 to pin 5. If a cable does not follow this convention, it will not work. Th above mentioned cable uses pins 1 and 3.
44 - What data is provided by a MIDI THRU connector?
The data provided by a MIDI THRU connector is a buffered feed of the input data that has not been processed in any way.
45 - What would you be most likely to use the MIDI OUT connector for on a keyboardless MIDI sound module.
The MIDI out connector of a keyboardless MIDI sound module would most likely be used to send control change messages, or may be used for 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?
If Pitch Bend or Control Change messages are used excessively in the above setup, latency will occur as these messages hold a large amount of data to be transmitted.
47 - Some MIDI equipment processes data from the IN connector before sending it to the THRU. What effect does this have on timing?
MIDI data that is processed from the IN connector before sending to the THRU will cause latency with respect to timing. There will be a delay while the data is processed from the IN connector.
48 - You are mixing MTC on the same cable as musical data. How might this affect the timing of notes?
If MIDI TimeCode is mixed on the same cable as musical data, it will cause delay(or latency) in the timing of the notes. This is because MIDI TimeCode will take up a sizeable chunk of the bandwidth which will enable less musical data messages to be transmitted simultaneously.
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?
Does this mean that the sequencer is not compatible with 32 note polyphony?
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?
If a complex series of notes and pitch bend movements cannot be completed simultaneously, then they should be recorded separately into the sequencer and then played back together.
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 a piano sound was recorded into a sequencer with large levels of sustain then another piano part was recorded on the same MIDI channel, the second recording would have the same characteristics as the first. This would be a large level of sustain.
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 a four bar drum loop that is set to be triggered from the sequencer on the first beat of bar 1 and the first beat of bar 5, is played from bar 3. The drum loop will not play until the first beat of bar 5 is reached. |
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Sun Oct 31, 2004 2:45 pm |
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seanm
Joined: 06 Sep 2004
Posts: 20
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| week 8 midi |
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hi ben sorry for delay pleaswe fing wk 8 answers
01 - What does MIDI stand for?
Musical Instrument Digital Interface
02 - Is MIDI a serial or parallel data flow?
In computer terms MIDI is a serial data link, where packets of information have to move in a single file, one after another.
03 - How does MIDI data contain timing information?
Alongside other data many MIDI devices send and receive MIDI clock data. This clock data uses 96 clock pulses (ticks) per whole note.
04 - What are the advantages and disadvantages of MIDI over digital audio?
Midi information contains only instructions to compatible devices it takes up considerably less space than digital audio, (As One minute of MIDI information takes up approximately 0.035MB of memory, compared to about 10MB for CD-quality stereo digital audio (16-bits at 44.1kHz), and over 34MB for 24-bit at 96kHz).
05 - Briefly describe the General MIDI standard
The General MIDI Standard was created so that generic Standard MIDI Files created on a sequencer or notation application may be played back on another device while preserving the integrity of the original selection. It is an addition to the original MIDI specification and 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.
Any MIDI device that conforms to the General MIDI Standard will assign each instrument to a specific number and will allocate at least a 24 note polyphonic capability.
06 - What other standards have evolved from GM?
Roland GS and Yamaha XG both evolved from GM
07 - What is the data rate of MIDI information in kbits?
MIDI data rate is 31.5Kbits per second.
08 - What is a UART?
Universal Asynchronous Receiver Transmitter. In MIDI, it is a part of the interface that forms the link between the processor and the MIDI sockets.
09 - What purpose does a MIDI Thru connection serve?
A Midi thru port transmits an exact duplicate of messages arriving at the in port and is used to pass externally generated MIDI messages on to an additional device.
10 - What is daisy-chaining in terms of MIDI connectivity, and what are its
disadvantages?
Daisy-chaining is the connecting together of a number of MIDI devices. The Midi out of the first device in the chain is connected to the Midi In of the next, which is then connects to the midi In of the next via its MIDI thru port.
Midi signals deteriorate slightly after they pass through each device leading to inaccuracies such as stuck notes or notes not being played at all.
11 - What are the advantages of multi-port MIDI interfaces?
Multi-port MIDI interfaces contain two or more MIDI output sockets, each containing its own set of Midi channels. MIDI data can be spread over the different channels to avoid “bottlenecks” resulting in stuck notes and notes which fail to play. These interfaces work alongside sequencing software (Steinberg etc.) which allows programmable MIDI routing and merging of MIDI Ins.
12 - What is a MIDI channel?
Within MIDI the information transmitted can be assigned to any one of 16 channels. Channels are set at the transmitting device and the receiving device. As a result up to 16 different channels can be played individually even though they are all wired together in one system.
13 - With reference to the MIDI interface and the MIDI specification explain why MIDI systems can only have 16 channels?
There can only be 16 channels because the channel nuber for any given event is encoded into the lowest 4 bits of the events status byte, therefore the channel number is always 0-15?
14 - What channel must be used for drums/percussion under the GM standard?
Percussion parts must be on midi channel 10 and a minimum set of 47 standards sound types, including the most common drum and latin percussion sounds must be provided. These must all be mapped in accordance with the general midi standard.
15 - What does Omni mean in terms of the reception of MIDI information on discrete channels?
Most MIDI instruments can be set to receive on any of the 16 MIDI channels, but there is also a setting called Omni mode, which allows the unit to respond to all incoming data, regardless of its channel.
16 - What is the status byte and what information will it typically include?
All midi messages are made up of a series of “words” (bytes), the first “word” is called the status word. It typically includes the command portion of the message (e.g. note on) and a midi channel number.
17 - What information is typically found in the data byte?
Data byte1 (word) contains key number data and data byte2 contains attack velocity data.
18 - Describe the three bytes of a MIDI note-on message.
Note on, Key number, attack velocity.
19 - What are control change (cc) messages?
MIDI can transmit the position of up 32 additional continuous controllers (wheels, slides, levers, pedals etc.) and 32 on/off switches (buttons, foot switches etc.). If a midi device recognises the controllers number it can respond to these messages.
20 - What is the purpose of system exclusive (sysex) messages?
System exclusive messages are MIDI messages but are only recognised by the device for which they were designed. This enables manufacturers to design and build devices with unique facilities and still conform to the MIDI standard.
21 - What is the difference between channel and system messages?
System messages will be received by all devices in the system. System messages contain no channel information and are available to all devices, which can make use of them. For instance messages relating to song position or song select.
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'?
In order to maximise the efficiency of MIDI transmissions running status allows a Midi message to be sent without its status byte as long as the last message had the same status. Running Status relies on the receiving device remembering the last status byte it received. When the device receives another message without the status byte it assumes it is dealing with a running status situation. Likewise the transmitting device remembers the last status byte it sent and if the next message has the same status byte knows it can send this message without its status byte.
25 - In running status, why is a velocity value of 0 treated as a note off message?
An attack velocity value of zero (0) has a particular meaning to midi instruments as they all recognise note on/keynumber/velocity = 0 as a note off message.
26 - What is the purpose of the 'Local' setting on MIDI devices?
MIDI devices which contain their own sound generation section (e.g. synths with optional MIDI capabilities) include a local setting. With the local on the devices internal sounds are triggered and MIDI data is transmitted. With local setting off the devices internal sounds are not triggered but keyboard messages are transmitted.
27 - What are system realtime messages?
System real time messages are used to transmit timing reference material and are available to all midi devices regardless of channel. There are no data words associated with system real time messages, each message consists of a single status word. These messages are MIDI clock, start, stop, continue, active sensing and system reset.
28 - What are Song position pointers (SPPs)?
Song position pointers are messages indicating a location within a MIDI sequence. The pointer number value contains the number of sixteenths since the start of the sequence. Using this devices can lock almost simultaneously to the correct bar and beat of the sequence.
29 - Briefly describe the MIDI TimeCode (MTC) protocol.
MIDI timecode uses absolute time in its messages (hours, minutes, frames and sub frames), unlike MIDI clock, which tracks the time of a sequence in beats and measures. As a result MTC can be easily translated into SMPTE enabling synchronisation with other non MIDI devices such as audio and video tape machines. In order to synchronise at the appropriate rate different frame rates can be selected:
24fps (frames per second) used in film.
25fps used for audio, video (PAL formats).
29.97fps NTSC formats.
30fps Monochrome television (US).
30 - Briefly describe the MIDI Machine Control (MMC) protocol.
MMC protocol uses MIDI commands to control the transport functions (stop/play/record/locate/rewind/fast forward) of another mechanical device (audio/video tape machines for instance). Selecting which device is master and which slave enables one to control the other.
31 - Why are modulation wheels often found on MIDI keyboards?
Modulation wheels are continuous controllers which can be used to send MIDI control messages. They are particularly useful for adding expression to a part, (tremolo, vibrato or pitch bending). Whilst they can be assigned to transmit any controller information they are the only controllers specifically defined within the MIDI specification.
32 - Define the term polyphony.
Polyphony describes an instruments ability to produce more than one note at a time. Typically modern instruments provide 64 note polyphony.
33 - Define the term multi-timbral
A multitimbral device is one which can playback more than one voice at a time in response to multiple MIDI channels for instance.
34 - What is aftertouch?
Aftertouch is a means of generating a control signal based on how much pressure is applied to the keys of a MIDI keyboard. Most devices with this facility do not respond to the pressure of each key simultaneously but detect the overall pressure using a sensing strip under the keys.
35 - What features do mixing consoles offer that can be controlled by MIDI?
Older analogue mixing consoles can offer automated muting which can provide more than just shutting down channels. Modern digital consoles automate just about every parameter which is adjustable.
36 - How do MIDI messages such as modulation, expression attempt to recreate the nuances of 'real instruments'?
To recreate real instruments and their timbral nuances is very difficult. MIDI messages offer a level control over “performance data” which enables the manipulation of performance parameters (e.g. vibrato, pitch bends, tremolo etc.) after they have been played. This degree of editing enables real instruments to emulated much more accurately.
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).
MIDI clock, start, stop, continue, active sensing and system reset. Song position pointer 1 and 2 and song select.
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).
SMPTE (Society of Motion Picture and Television Engineers)
FSK (Frequency Shift Key)
39 - MIDI timecode quarter-frame, song position pointer, song select, tune request and end of exclusive are all what type of MIDI message?
They are all MIDI system messages.
40 - What does the first bit of each byte of a MIDI message signify?
A “1” defines the byte as a status byte. A “0” defines the byte as a data byte.
41 - Explain the relationship of sequencer tracks, MIDI channels and synthesiser voices.
When opening a midi track in a sequencer it is possible to assign a midi device to this track. The different voices of this device can be assigned their own midi channel for record and playback purposes. Many VST instruments open up a variety of channels in the sequencer when selected, which can be assigned to any voice available on the device.
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.
MIDI control data can be physically input using:
The wheel controllers on the keyboard.
The knobs which accompany many controller keyboards.
It can usually be drawn in manually using the mouse within most sequencer software.
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?
According to the MIDI 1.0 Specification, the only approved MIDI connector is a 5-pin DIN connector. But this is a different kind of 5 pin DIN, it is certainly possible to send MIDI messages using other connectors and cables, but it can cause interconnection problems. A major design goal of MIDI is to prevent any ground loops that might occur with the MIDI cables. This is done by using a balanced current loop through an opto-isolator and only grounding the MIDI outputs. The MIDI IN connector is not grounded to the receiver's chassis. When done correctly, there are no ground loops and no hum or other noises caused by the MIDI setup.
44 - What data is provided by a MIDI THRU connector?
The MIDI thru in itself produces no data it merely passes the on which it receieves from the MIDI In connector. There is however a small amount of distortion caused to the signal.
45 - What would you be most likely to use the MIDI OUT connector for on a keyboardless MIDI sound module
To record MIDI controller information into a software 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?
MIDI overload resulting in latency problems and/or MIDI information failing to reach its destination for instance notes continuing ad infinitum.
47 - Some MIDI equipment processes data from the IN connector before sending it to the THRU. What effect does this have on timing?
The time taken to process this data can increase latency.
48 - You are mixing MTC on the same cable as musical data. How might this affect the timing of notes?
In MIDI, clock messages have priority over all other messages to insure accurate timekeeping as a result the musical data might suffer from increased latency.
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?
Similar to acoustic feedback a MIDI loop has occurred where midi information is finding its way back to the keyboard and being re-triggered. More than likely “local off” has not been selected.
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?
It would be much easier to play the melody first and record the pitch bend “performance” later.
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?
The sustain controller data will be applied to the new 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?
Silence (from the drum loop) until the first beat of bar 5. |
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Wed Nov 03, 2004 4:26 pm |
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