Audio for video

'Audio for video’ is a term that covers a wide range of activities including music, dialogue and sound effects. I'll assume that you are primarily interested in recording music to picture. As well as all the components of the recording studio, you will also need a video machine (it doesn't have to be able to record) and a synchronizer. You can record music to picture with a MIDI setup, in which case the requirements for the synchronizer are somewhat less stringent.

You can easily use a domestic VHS for recording music to picture. All you have to do is get the production company to send you a cassette of the program with LTC (longitudinal timecode - usually just called timecode) on the audio track and preferably also burnt in timecode, where the timecode numbers appear on the screen. If you have a digital multitrack, then you will be able to buy an accessory card or unit which will allow it to synchronize to timecode in a basic way. The only problem you will have is that when you wind the video back to the start of the program, the multitrack will stay firmly in stop mode until the video starts playing and timecode is issued once more. Only then does it start to rewind. This is a nuisance, but it doesn't stop you working. The next step is to buy a professional grade video and slightly more sophisticated synchronizer that will accept transport commands so that as soon as you start rewinding the video, the tape will rewind too. This method of operation is much quicker, but you'll pay for it.

If you are ambitious and intend synchronizing dialogue and sound effects to picture, then you need a hard disk recorder that is suited to the task (some are not). Briefly, you should look at computer based hard disk recording systems where you can see the audio split up into segments on the screen. If the system offers this, and can synchronize successfully to SMPTE/EBU timecode or MTC (MIDI timecode) then it is worth your while getting a thorough demonstration and test drive.

As you will realize by now, if you want to synchronize a MIDI sequencer with multitrack tape, or if you want to synchronize a multitrack to video, then you need a synchronizer in your system. Synchronization revolves around SMPTE/EBU timecode which is in essence a numerical identification of every frame on the video in hours:minutes:seconds:frames form. Timecode is recorded either as an audio signal on one track of the multitrack or on an audio track of the video. A digital multitrack can, with the right accessory, record timecode onto a data area of the tape so you don't lose an audio track. In a simple system, the master machine (the multitrack or video) will send timecode to the synchronizer which will control the slave machine in such a way that it always records or plays in sync with the master. The slave could be a MIDI system or a multitrack recorder. Since SMPTE/EBU timecode has all the appearances of being an audio signal, it is tempting to treat it as an audio signal and allow it to enter areas that should belong only to real audio - the mixing console for instance. This isn't a good idea since timecode sounds awful and easily leaks into audio signal paths where you would rather it didn't. The answer is to run timecode directly from the generator to the multitrack (in your project studio you should never need to stripe timecode onto a video, a procedure which requires a more expensive timecode generator with a video input to do properly), and take the timecode output from the multitrack or video directly to the synchronizer. The problem you will have is that when you are striping timecode onto the multitrack tape you will need to control the level, yet many timecode generators have no output level control! The answer is either temporarily go through the mixer to stripe timecode then disconnect the generator, or buy a generator with an output level control. I know which solution I prefer. Since this book is about setting up a studio, you will have to look elsewhere to see how synchronizer systems work because they can get quite complicated, but Figure 1.9 shows a couple of simple systems so that at least you know how they should be connected.