Avid DNxHD large file audio render problem

cold-ones wrote on 8/29/2011, 2:24 PM

Wonder if any of you have the time/interest to replicate this. I render backup copies of my HD projects to the Avid Quicktime format. But I'm getting a weird audio error when I bring this movie back into a Vegas timeline.

At or about frame 100,000 (around 55:37 in drop frame time) the synched audio stops, and audio from an earlier portion of the video continues to the end of the movie (another 30 minutes or so). Oddly, the track waveform for this out-of-synch audio matches the correct synched audio, but the actual sound is from an earlier portion of the file.

The audio plays perfectly in VLC & Quicktime players. But I'm guessing that there's something about the large filesize (over 100MB) that is throwing off Vegas. Has anyone seen this problem?

Render settings
Avid DNxHD: 709; no alpha, 1080i/59.94 DNxHD 145 8-bit
Audio: uncompressed, 48k, 16bit, stereo

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cold-ones wrote on 8/31/2011, 3:06 PM

For me, the only way the re-rendering of the audio would work is if the Quicktime movie in question had been rendered from my own project. Then I can go back to the original project and re-render the audio, and synch it on a new timeline with the Quicktime video track.

But if someone were to send me a long Quicktime movie that they created, I wouldn't be able to re-render its audio within Vegas, because the only audio I would have to work with is the Quicktime movie, which un-synchs after 55 minutes or so under Vegas playback.

However, I could use Quicktime (or another app) to load the Quicktime movie, and then export an audio file from there. So it could work, as long as you don't use Vegas to play the Quicktime audio.

amendegw wrote on 8/31/2011, 3:16 PM

"But if someone were to send me a long Quicktime movie that they created, I wouldn't be able to re-render its audio within Vegas, because the only audio I would have to work with is the Quicktime movie, which un-synchs after 55 minutes or so under Vegas playback."Something is strange here, because a render-to-new-track works prefectly for me.

The only time my audio gets out-of-sync is when I manually move the timeline cursor past the 55 min mark (or there abouts - I didn't confirm the exact time).

Did you try doing a Audio Only render-to-new-track?

I'd love to see a third person test this and see what the consensus is.

...Jerry

cold-ones wrote on 8/31/2011, 3:25 PM

I think I followed your suggestion exactly, and the rendered audio file was unsynched. I did it again just now, from another random selection, and the audio file that is rendered is, I believe, the unsyched audio poached from the very beginning of the movie. I tried various things, like deleted the quicktime video track, same result.

amendegw wrote on 8/31/2011, 3:59 PM

All I can say is "strange" - the workaround works for me.

Since I can't exactly reproduce your projects behavior, I think I've exhausted my ability to help.

...Jerry