This IS the Avid L2: Re: [Avid-L2] ProResHQ AMA Problem

Wednesday, July 30, 2014

Re: [Avid-L2] ProResHQ AMA Problem - Half Solved

You might look at the following links Jim Feeley posted recently in reponse to a different issue. Since some audio recorders do not start/stop their recording on video frame boundaries, it appears Avid does some padding to get audio and video to be the same length. I wonder if that is what you are seeing (in which case I think it would be fairly normal behaviour.)

Here's the links:

Avid users discussion:  BUG: Match alternates out of Sync to AAF  http://duc.avid.com/showthread.php?p=2094420    Location sound discussion:  Conformed original BWAVs are out of sync by up to a frame compared to the AAF  http://jwsoundgroup.net/index.php?/topic/19496-conformed-original-bwavs-are-out-of-sync-by-up-to-a-frame-compared-to-the-aaf/ 
  If you could determine how much the audio and video differ in length (maybe via quicktime pro?) that might give some insight.    Cheers,  --Michael

On 2014-07-30, 6:24 AM, hoplist@hillmanncarr.com [Avid-L2] wrote:

On Jul 29, 2014, at 6:04 PM, tcurren@aol.com [Avid-L2] <Avid-L2@yahoogroups.com> wrote:

As I said before, I export the audio and reimport it to solve the issue.

I have indeed worked around the problem by transcoding, but now I know that there is something bad going on. It's not merely a bug or limitation. Avid is adjusting the audio (at least for AMA playback). If it is also doing this in import/transcode, I might not see this immediately. I don't want this to bite me in the butt later. Normally if the audio is short, it just stops before video.

Has anyone ever seen mismatched video/audio duration in camera original before and measurable in frames?

I am never satisfied with workarounds. I want to understand. Is this a error in the way AMA is working now, or is a more serious problem with the files themselves. That second possibly is concerns me most. Will I see this problem in the future with any files from a Sound Devices recorder? That would be surprising... and bad since we use them about half the time. Or was the recorder doing something wrong.

Tod Hopkins
Hillmann & Carr Inc.