audio drift in exported quicktimes

[Rex Teese]

Posting for a friend, so this is the information as best as I know it.

Using the 3.1.8 version of redcine to export avid DNXHD codec quicktimes. Some of the shots are up to 23 minutes long. After the export, the new quicktime's (the 23 minute long ones) audio drifts by up to 1.5 seconds at the end. We tried to resync in the avid using location sound files, but they won't hold sync either. Avid project is set up as 23.976, footage was shot at 23.98 and output thru redcine as 23.98. He's trying a test outputing from redcine as 23.976, but I haven't heard the results yet. It likely doesn't matter, but sound was recorded at 29.97 ndf. Red proxies play fine. The culprit is definitely redcine, we just can't figure out why.

Thanks.

 

[MichaelP]

Just to be exact on the production frame rates and all.

Picture at 23.976
Sound at 29.97 NDF @ 48kHz (not 48.048, etc.)

When exporting the QT wrapped DNxHD files, look at the info of the movie and see what frame rate it is indicated to be - Know that QT will indicate 23.976 as 23.98 - who knows what happens to that other .001%. And see if the audio is indicated at 48kHz.

Do these files drift over time?

If all that looks good - type this into the Media Composer console

ignoreqtrate true

To turn it back off type: ignoreqtrate false
and try importing the video and the original sound file and sync again.

Let us know what happened. These answers will pinpoint where the problems may lie.

Michael