Using Timecodes (Part 5)
In the final part of his series on the synchronisation of audio and video, Francis Rumsey summarises the possible applications of timecodes in helping to automate the music studio.
By way of finishing this series, let's take a look at other areas of the music studio where, in addition to the locking of tape machines, timecode is finding a place as a common reference for a wide variety of 'automated' equipment.
Yes, Fostex again, and another product which does a marvellous job of linking two worlds together: those of composition and machine control. It is quite feasible that in the past you might have needed quite a large number of pulse tracks of various kinds recorded on your multitrack tape, in order to trigger drum machines, synths etc, as well as a timecode track if any other machine transports were to be locked to it. Naturally, this wastes space on the tape where you could be recording music, and there is the added problem that no real standardisation exists between manufacturers of 'triggerable' musical instruments for a trigger pulse which may be recorded on tape.
Whereas MIDI sequencers refer to positions in a piece of music by using the relatively musical divisions of 'measure', 'bar', and 'beat', timecode counts in hours, minutes, seconds and frames: both methods being extremely useful in the right application. The SMPTE/MIDI autolocator performs the task of reconciling the two in a manner which 'time-stamps' the MIDI divisions of the song so that one timecode track may suffice for the time-referencing of all the instruments in the system via a sequencer, with the added advantage of being able to use that timecode track for other applications at the same time.
Once the initial timing relationship between the song sequence and timecode has been established, it becomes feasible to use the autolocator for searching both the tape transport and the musical instruments to the same point in the song, either by entering a timecode location in the standard form, or referring to the location in musical terms by bar number, beat etc.
Most ingeniously, this Fostex device (designated the Model 4050) is capable of 'time compression' or 'expansion' in the MIDI domain with regard to timecode. This means that the long-term relationship between the timecode and the music can be changed, provided that the music all still exists in the memory of a sequencer, allowing the composer to match the length of his musical sequence to a particular duration in timecode terms. Clearly the speed of the sequence would be altered to fit the same number of notes into the required time period, but the calculation of the percentage speed - change is not left up to trial and error on your behalf: a useful time-saver.
Integrated in the 4050 is a timecode generator, a metronome, and the facility to dump all the cue-point and MIDI information onto a piece of blanktape, in the form of a data burst which might subsequently be re-loaded at a laterdate.
A subject in itself really, but worth a mention here because a console automation system could be yet another destination for that all-important timecode track on your tape.
Most modern console automation systems use timecode as the reference against which all the data about positions of controls is stored. It is normal these days for such information to be recorded on floppy disks, as opposed to the older method of laying down a separate 'automation data' track on the tape recorder which would replay the information in real-time, along with the music.
The automation of a mixing console may take a number of forms, ranging from the relatively simple memorising of certain switch positions to full dynamic recall of moving fader levels, and here again we are beginning to see some interesting developments in the integration of MIDI sequencing with basic console control. Some of the smaller mixing console manufacturers have been directing their attention towards a desk-top, computer-based system which uses timecode or a pulse-track to synchronise console channel routing (selecting the final destination of each input) and channel muting (effectively turning a particular channel 'on' or 'off') to the MIDI sequence, a system which, in conjunction with something like the autolocator described above, could provide almost total integration of studio control.
Even the most basic form of automation, implemented using a home computer interfaced to the routing/muting controls on each channel, opens the door to possibilities for creating sequences of mutes and routing changes which might otherwise be impossible for speed or number-of-hands reasons. If the integration between sequencer, console and timecode is complete enough, it becomes possible to prepare a lot of things 'off-line': in other words, using the computer you could programme in mutes and routing changes against MIDI song-pointers or timecode locations before the mixdown started, leaving you free to control important things like level, panning and EQ in realtime.
If you think about the amount of background noise produced by a lot of electronic musical instruments you will appreciate the advantages of being able to mute a channel for very short periods of time (over a few bars rest, for instance) in order to minimise the overall build-up of noise from different sources. Automation of console muting against timecode immediately provides the operator with a means of achieving humanly impossible combinations of short-term mutes on different channels. Often, the only noise you hear on a compact disc is that of the synthesizers!
Although these are early days to see exactly how such total integration might be achieved, we can see what is becoming possible. It still requires certain manufacturers to sort out things like which timecode standards to employ in some devices, and to watch the ways in which people work so as to determine their needs. A bit of video experience is required of musical instrument manufacturers and, conversely, the 'established' pro-audio and video manufacturers should watch the music technology industry carefully in order that they aren't left standing in a revolution concerning the way in which many people compose and record music these days.
Returning to the subject of this series, it seems that the use of timecode in music studios is on the increase: one timecode track might be feeding a machine synchroniser, a MIDI synchroniser, and a console automation system all at the same time. So timecode's pretty important really. One thing's for certain... you'd better not erase it!
Erratum In Part 3 of this series [April 86], the captions to Figure 2 were accidentally swapped over. The bottom diagram should have read: 'Positions Of Heads On A Single-Head Machine'.
Feature by Francis Rumsey
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