Strange, Variable Audio Sync Issue

[kalorx]

I'm sorry if it turns out to be the wrong forum category for this, but it is an audio problem, and I'm not sure where else to post. So here's the issue:

I'm backing up Firefly episode 2. I used all the same methods to encode and mux the video and audio as I always do. For example, the same ripping and muxing methods worked just fine for Serenity and Firefly episode 1. However, for some odd reason, the audio, after being muxed, starts out synced at the beginning of the video, but by the end is off by some undetermined amount. This is obviously not an issue that merely changing the delay will fix.

I ran into this problem once before when using MP4Box; I had to manually tell MP4Box that the input video was 23.976fps, and that fixed the issue. However, I'm not using MP4Box right now! I'm using MKVmerge -- as I always do -- and I can't make heads or tails of the issue. I've never run into this problem when making MKVs with MKVmerge before.

The original AC3 audio file has a delay of 5ms, so I used BeSweet (BeLight GUI) to encode into NeroDigital HE-AAC at 5ms. But the sync issue occurs. I tried changing the delay in BeSweet. I then tried changing the delay in MKVmerge. I experimented for nearly two hours, and no delay came out right as the needed delay seems to change with every passing frame.

I'm at a total loss here. Any help would be greatly appreciated!

Thanks,

Robert Aronson

[kalorx]

Does anyone have any ideas?

[gameplaya15143]

Check the duration of the audio and the video tracks. My guess would be that the video framerate isn't constant. Try using 'force film' in dgindex and see how it goes.

[kalorx]

The audio and video durations are ever so slightly different.

Video - 00:41:52.343
Audio - 00:41:52.753

I could try force film, but I've heard that can screw up things on the decombing end and can create stuttering video.

[kalorx]

Even when I force-film the video, its resulting length is still 00:41:52.343, which is slightly shorter than the audio.

It seems something must be wrong on the audio end. EDIT: I just checked, and I'm using the latest version of BeLight, which itself is bundled with the latest version of BeSweet.

[kalorx]

No solutions?

[gameplaya15143]

Does it sync back up towards the end of the video?

This does indeed seem to be an odd problem.

Might want to try using 'respect pulldown flags' as well.

[kalorx]

The audio only gets worse the farther into the video it goes.

And I honored pulldown flags the first time I encoded the video, so I know that won't help.

As I said, I've had this problem before... but only when using MP4Box to create an MP4, and all I had to do was enter "-23.976" and it fixed it. This must be a framerate issue. It must be.