I'm editing a film and have been given external audio, recorded using a sounddev 633 I believe.

The external audio files have 5 mono tracks when I open them in Avid, some files have just 4 mono tracks, some just 2.

My question is, do I need to keep all the duplicated mono tracks? why would the sound person have recorded with so many tracks of the same thing? can I just delete all the other tracks and just use one track for each file?

I'm trying to sync external audio to the camera audio in plurel eyes and its struggling to do it with so many tracks.


  • You should be coordinating with the rest of the technical team, including whoever is doing audio post and the production sound crew to make sure everyone is on the same page regarding the editing and production process. One super-important question you should have straight is whether you are currently holding all the audio and have to deliver it to audio post along with the edited footage, or does audio post have their own copy and do they just need your EDL? Also your question is better asked of the production sound crew than asked of strangers on the Internet. Commented Dec 9, 2017 at 13:24

2 Answers 2


633 will in most cases be recording two mix tracks (L,R) and multiple ISO tracks. If there is boom and wireless lavaler being recorded usual practice is boom on tbe left and radios mixed to right. This is why you are seeing duplication. In post you can ignore the first two mix tracks and do your edit from the iso tracks.


Don't delete those tracks. It's possible this is a multichannel recording, for 5.1 mastering. In the 4 and 2 channel situation, it could be boom and omni-directional mics used in combination to capture the scene better. Talk to the person who originally recorded and see if they have notes or specs on what each channel represents in each scene.

If 5.1 mastering is too much work, you could down mix to 2 channel, but knowing what each of your recordings is can be critical.

  • Hi Evan, thanks for your answer. I did consider whether this was 5.1 audio, but I couldn't figure it out from looking at the audio tracks or the metadata in the files. Is there any way to know this or would we always need to speak to the recordist to find out? Also, just to be clear, are you saying to do an audio mixdown of all the mono tracks to just 2 tracks? should i make these stereo tracks and then pan one left, one right? thanks for your help.
    – Ange17
    Commented Dec 3, 2017 at 6:35
  • 1
    Golden rule: If in doubt, ask. Better to ask a dumb question & be thought a fool than mix down someone else's hard work to stereo & be confirmed as one ;)
    – Tetsujin
    Commented Dec 5, 2017 at 12:57
  • How did you look at the metadata? One of the very best ways to analyze is through Handbrake handbrake.fr It uses ffmpeg and several other open source libraries to really dig in. Handbrake's interface only works with video files but the analysis works fine on audio input. I open the program, then Window > Activity Window. Then choose my file. I opened a basic mp4 AAC audio and got 34 lines of output from Handbrake. It's essentially reading the explicit header exhaustively and then performing some implicit analysis based on the data. Otherwise, you'll have to watch the video and guess.
    – Evan C
    Commented Dec 6, 2017 at 1:13
  • 1
    If it's production dialog I'd be surprised if it were recorded for surround sound, as for delivery it would generally be (or have to be?) all on the center channel. My first thought was the different channels may have different mic gains as safeties. Commented Dec 9, 2017 at 13:21

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