2 versions of a film - combine best video with best audio

[pooksahib]

As the title says, I have two versions of a film, one (AAA) has the better PQ and the other (BBB) has the best sound. AAA runs at 29.97fps and BBB at 23.976fps. I'm assuming that this is the reason why my new version, CCC, (made using mkvtoolnix) starts in sync but then goes farther an farther out.

Is there a way of making a CCC which stays in sync? Many thanks.

[jagabo]

29.97 and 23.976 fps would normally have exactly the same running time. Something else is going on. You may have different cuts of the movie. Or maybe a PAL to NTSC conversion. More detail is needed. Unprocessed samples of the videos would be helpful.

[pooksahib]

Hi jagabo, thanks for the reply. As requested:

[Luke M]

I don't see any drift, the samples are in sync. Not a frame rate issue.

[jagabo]

AAA was converted from 23.976 fps to 29.97 fps by duplicating every 4th frame. ie 01234567 became 0123345677. Otherwise the frames coincide perfectly. There is no difference in running time so the audio matches perfectly. If the audio doesn't line up for the entire video you have different cuts of the movie.

[pooksahib]

OK, thanks guys. When I demuxed the audio from BBB, mkvtoolnix generated four warnings:

This audio track contains 114 bytes of invalid data which were skipped before timestamp 00:14:31.438328544. The audio/video synchronization may have been lost.
This audio track contains 72 bytes of invalid data which were skipped before timestamp 00:23:46.990333440. The audio/video synchronization may have been lost.
This audio track contains 672 bytes of invalid data which were skipped before timestamp 00:39:43.918336128. The audio/video synchronization may have been lost.
This audio track contains 177 bytes of invalid data which were skipped before timestamp 00:47:28.750334976. The audio/video synchronization may have been lost.

Doesn't seem like a lot of bytes to me but if I could 'add them back' might it fix the sync problem with CCC?

[ProWo]

Use clever ffmpeg-GUI.
Load AAA, click main, click multiplex, drag & drop BBB, select the tracks like in the picture, click multiplex.
Done.


[Attachment 77777 - Click to enlarge]

[pooksahib]

Thanks, ProWo, that's a nice tool. However, it gives the same output as muxing with mkvtoolnix i.e. loss of sync as the film progresses. What I'll probably end up doing is an edit of each scene using audioshift as necessary then stitch the scenes.

[ProWo]

You should extract both audiotracks AAA and BBB and compare them in Audacity.

[johns0]

Most likely there are different scene changes that have longer or shorter times than the other,if that's the case then you will have to match the scene changes throughout and there could be a dozen or more,.

[jagabo]

You should extract both audiotracks AAA and BBB and compare them in Audacity.

I did that with the samples and they were essentially identical in terms of timing (aside from a ~7 ms initial delay).

[poisondeathray]

This audio track contains 114 bytes of invalid data which were skipped before timestamp 00:14:31.438328544

The 1st error occurs @ 00:14:31.438328544 , which is beyond the duration of sample uploaded .


You can try demuxing the audio to ac3 and running it through delaycut to fix the errors (pay attention to what the log says about the errors), or maybe eac3to

[pooksahib]

Hi poisondeathray. I'm assuming that the '-info' option of delaycut will flag any errors (although the readme just says "-info: Outputs info about input file in log file"). Here's what I got:

Bitrate=192
Actual rate=192
Sampling Frec=48000
TotalFrames=143876
Bytesperframe= 768.0000
Filesize=110497502
FrameDuration= 32.0000
Framespersecond= 31.2500
Duration=01:16:44.062
Channels mode=2/0: L+R
LFE=LFE: Not present

Pretty innocuous, I'd say. Is that what you meant by 'running it through delaycut'? Thanks.

[poisondeathray]

Process the file with delaycut and it will try to fix CRC errors if you enable the "fix" option. It cannot read errors in the middle of the stream without processing the file. After processing the file look at the info log to see what was fixed (if anything)

[pooksahib]

Understood. Here are some highlights from the 'fix' log:
Time 01:26:50.912; Frame#= 162842. Some basic parameters changed between Frame #142331 and this frame
Time 01:26:50.912; Frame#= 162842. Crc1 error SILENCED: read = 52c8; calculated=80e6
Time 01:26:50.912; Frame#= 162842. Crc2 error SILENCED: read = ca39; calculated=457e
Time 01:26:50.944; Frame#= 162843. Unsynchronized frame...REWINDED 105 bytes. Found new synch word
Time 01:26:50.976; Frame#= 162844. Some basic parameters changed between Frame #162842 and this frame
Time 01:26:50.976; Frame#= 162844. Crc1 error SILENCED: read = a6c9; calculated=4bce
Time 01:26:50.976; Frame#= 162844. Crc2 error SILENCED: read = 39f0; calculated=31ea
Time 01:26:51.008; Frame#= 162845. Unsynchronized frame...NOT FIXED. Reached end of file
Number of written frames = 143299
Number of Errors= 19567

I muxed the 'fixed' audio with the video file but the sync issue remains. Never mind. I'm sure I can make an acceptable edit on a scene-by-scene basis.
Thanks to all.