By Fred Ginsburg CAS PhD
Today’s sound mixer or videographer has a choice of recording location audio to one or multiple recording tracks. In addition to being able to record sound “direct to video” — it is pretty much the norm to also record simultaneously to a dedicated audio recorder (the process known as “double system sound”) and then to sync these tracks to the picture during the editing process.
The question that I get most often at seminars or from my college students is “What is the best way to effectively utilize multiple tracks in the field?”
In the olde days of filmmaking, sound mixers only had one track available to record on. The recorder of choice, from the 60’s thru the late 80’s, was the legendary Nagra reel-to-reel sync recorder.
On a Hollywood set, all of our microphones (booms, planted mics, lavs, and wireless mics) were routed through a mixing panel and then mixed live to the single soundtrack. For these live mixers, we would open and close (mix) the various mics in order to achieve consistency of volume and perspective, while avoiding phasing issues that would occur if multiple mics picked up the same audio. These live mixes were known as the “Production Track” and served as the temporary soundtrack for dailies and the initial picture cut.
After the picture was declared “locked”, the sound editors would begin to work their magic. The single production track would be broken down (“checker boarded”) and moved to multiple editing tracks in order to separate characters, sound effects, ambiance, and other elements. The editors would augment these original tracks with ADR, Foley, sound effects, backgrounds, and so on. What began as one production track might evolve into over 100 separate tracks going in to the final mixdown!
By the mid to late 1980’s, we saw the emergence of two track field recording along with timecode with recorders such as the Nagra IV-STC and, later on, the Fostex PD4 digital recorder. Note that the term “two track” does not mean the same thing as stereo.
Two track refers to two monaural tracks containing completely different audio content. Stereo means that much of the content is replicated onto both tracks. By altering the volume or balance of each mic relative to left/right, the brain is fooled into thinking that the sound originates spatially arranged left to right in front of us.
Another term for “two track” is “two track discreet”, which emphasizes that there is no overlapping of the same mics onto both tracks. During editing, we treat both tracks as center screen monaural and NOT as representative as LEFT or RIGHT. Eventually, the editors and post-production mixers will pan those mono tracks to surround stereo assignments for theatrical playback (such as 5.1 or 7.1 surround systems).
But as location mixers, we think of them in our heads as just two in-boxes. The only time we break out bona-fide “stereo” microphones would be for music or background ambiance tracks.
So how best to deploy two tracks?
An early school of thought was to record the live dialogue mix onto Track One (aka Left) and then to utilize Track Two (aka Right) for sound effects and ambiance.
The other plan was to record some mics onto Track One, and separate others onto Track Two. This could avoid phasing issues between booms and lavs (or other open mics). If two actors were on lavs, then splitting them across tracks would protect each actor from phasing as well as from clothing noise stemming from the other actor’s microphone. The only difficulty is that the editor is forced to do some selective mixing during the basic picture edit in order for the dailies to sound sharp and not suffer from the phasing (hollowness, reverb) created when both tracks are played back at equal volume simultaneously.
Another strategy for using two tracks of audio is to just record them as duplicate mono tracks. Maybe there is only one mic on the set…. So what would be gained by using two tracks? If you record only to one track, and leave the second track blank, you would only hear out of one side of your headphones or play back the scene out of one side of the video monitor (TV). Yeah, if you know about adapters, you could Y-cable the audio to both sides. But the simplest solution is just record identical audio onto both Track One (L) and Track Two (R).
When the same audio content is recorded equally onto both tracks, it is referred to as “dual mono”.
There is another way to utilize two tracks. If we are savvy enough with our routing or adapters not to worry about lop-sided playback levels – we could adjust our “dual mono” recording so that Track Two is recorded at 10 to 15dB LOWER than Track One. Same audio content, but Track Two is attenuated so that an unexpected loud outburst from an actor is less likely to clip or distort due to over modulation (being too loud).
During picture cutting, the editor only has to drop down to the second audio track on the timeline in order to cut around a line or two of distorted dialogue on the primary track. This saves a ton of time and effort by not having to reconstruct the scene with ADR (or ISO mic tracks) and new background tracks.
We call this lop-sided or protective use of the two tracks, “dual attenuated mono”. It is similar to a photographer bracketing their exposure.
Eventually Hollywood advanced to four-track digital recorders. What to do with the four tracks now available to use?
One technique is to not mix the mics, but to record each input onto its own discreet track. This requires less judgement and skill than live mixing; hence these sound people became known as “recordists”.
Note that the Hollywood sound union defines “recordist” as the technician responsible for loading and operating the sound recording devices, but not for making any creative decisions as to content. The mix levels were done by a “sound mixer” at a mixing panel. So if you are just getting started in this business, do not call yourself a “recordist”. It may sound hip to the uninformed, but it is the incorrect job title, at least in the USA.
If you record all four tracks as discreet inputs, the editor will have to do a lot of work to pre-mix the dailies. If all four tracks are just played wide open, the results will sound horrible. But without this pre-mix, it is difficult to ascertain the quality of the individually recorded tracks. It can be done, but it is tedious work. Most likely, the production company will just order up a lot of ADR and not pick through your ISO’s to see what is worth keeping.
The term “ISO” means that the recorded track represents just one input (microphone) and that it was minimally mixed or hardly adjusted, but rather recorded raw (as in set it and forget it; let the editor sort it out).
A more practical strategy would be to record one live mix along with three ISO tracks of the key players. The live mix would serve as the basis for the picture edit; and then the sound editors could avail themselves of the ISO tracks if they needed to fix something.
My personal approach is to do a “dual attenuated mono” mix across two of the tracks, and only to record two ISO’s. Most problems are due to unexpected outbursts that clip or distort; and this solves that problem easily for the editor.
On larger shows, Hollywood prefers to use multi-track recorders that offer 10 or more recordable tracks. Most of these recorders are set up to take at least 8 individual inputs, along with a master Left/Right live mix derived from those ISO inputs.
We treat the Left/Right master tracks as our live mix, and record the mix as dual attenuated mono. Left representing the primary mixdown track, and Right being the attenuated track. This master mix is often recorded as an interleaved STEREO track (not individual mono tracks). However, the ISO tracks will show up as mono tracks.
During editing, the STEREO track needs to be reformatted/converted into two mono tracks, which is easily accomplished by any editing software platform.
One final note. When you are using multiple tracks, whether it be 4 tracks, 10 tracks, or even more – there are two important procedures to adhere to.
Always arm and record ALL of your available tracks, whether you need them that day or not. Just leave the unused tracks as MUTE, but record them as empty tracks. Otherwise, the lab or the editors will not know if they have imported all of the tracks for that set of dailies. Later, inserting them and intercutting them on the timeline can get confusing if all the audio clips are not the same number of tracks. Do not assume that you will never need the extra tracks; directors have a knack for surprising you later in the shooting schedule. Digital memory is cheap and plentiful; just use everything.
The second thing that you should always practice on the set is consistency in track assignments. Most of your ISO tracks are predictable: one or two booms, one or two planted mics, and probably a bunch of lavs & radio mics on your key players. So pre-assign your tracks. It makes the editor’s job so much easier to know that the ISO of the boom will always be on track 1, and that each actor will show up on their own track number. If you are not using the second boom, or some actors are not in the scene – try to just leave those tracks empty. Do not reshuffle to fill in the blanks. If you do need to temporarily re-assign an unused track to a new actor – then make it super obvious on your sound report. But leave as many of the original track assignments as possible intact.