The first thing that came to mind is that you're exporting NDF when it should be DF, however, that kind of thing should only be affecting the timecode numbers assigned to the frames, not the actual number of frames exported. So, overlay that exported clip back onto the sequence and apply a 50% Crop. See if you can find where it goes out?
Thanks for your suggestions!
I'm pretty sure my files and sequence are DF, but I'll check everything again.
I hadn't thought of superimposing the two files...I'll definitely try that and report my findings.
Does it make sense that this issue doesn't show up when encoding to mpeg2 blu-ray, and doesn't show up when exporting to the non-blu-ray h.264 (with multiplexing)?
None of it makes sense. I'm hoping the comparison might shed some insight.
I found that, of the sequences I've been working with, those that were created by dragging the footage onto the "new" icon were NDF. Sequences that I initiated from scratch are DF. But even after exporting to h.264 from a "DF" sequence, when re-imported and dropped on the "new" icon, a NDF sequence was created.
So...I established a new DF AVI sequence, and copied the source footage into it. This gave me a 720P59.94 DF cineform avi sequence, which doesn't seem any different than the NDF predecessor. Audio and video are in sync from beginning to end - 42 minutes duration.
I did a fresh export from this sequence to the adobe h.264 blu-ray preset (720P59.94, dolby, high, 4.1).
I then re-imported the resulting m4v, and dragged it onto an unused track in the source sequence. As expected, It extended beyond the source by 78 frames (in 42 minutes), and had the gradual drift out of sync.
I applied the 50 % crop, and looked for the first sign of change between the two tracks. I noted that at 00;01;01;42, the h.264 "encode" track seem to take one step backward, resulting in a 2 frame difference for a while. I tried to find the next exact place where a change occur, but found it impossible to do so.
Since this seems kind of weird, it would be helpful to know if anyone else has been successful in exporting a 720P59.94 sequence to h.264 blu-ray, without gradual loss of sync. The duration would need to be long enough for the sync loss to be obvious - 15 minutes or so?
That step back isn't normal. I'm testing it here now.
I do in fact see a similar issue. I didn't check to see if the export loops back, but a 20 minute export ended up with about 30 extra frames.
Thanks so much for taking the time to look at this! Let me know if I should file a bug report.
For what it's worth, I know I saw the frame reverse direction for one count, then resume in the forward. Although I couldn't detect it when I went back to it , the 2 count difference in frames between the 2 tracks was definitly there.
You should file it.