MKVToolnixGUI: Audio Track Contains Invalid Data

[koberulz]

track 0: This audio track contains 107 bytes of invalid data which were skipped before timestamp 00:54:26.016000000. The audio/video synchronization may have been lost.

And yes, it is indeed out of sync. Trying to convert this from AVI to MKV, just dragging it in, editing some of the metadata, and multiplexing:

General
Complete name                            : a.avi
Format                                   : AVI
Format/Info                              : Audio Video Interleave
File size                                : 1.28 GiB
Duration                                 : 1 h 41 min
Overall bit rate                         : 1 799 kb/s
Writing library                          : VirtualDub build 29808/release

Video
ID                                       : 0
Format                                   : MPEG-4 Visual
Format settings, BVOP                    : Yes
Format settings, QPel                    : No
Format settings, GMC                     : No warppoints
Format settings, Matrix                  : Default (H.263)
Codec ID                                 : XVID
Codec ID/Hint                            : XviD
Duration                                 : 1 h 41 min
Bit rate                                 : 1 709 kb/s
Width                                    : 320 pixels
Height                                   : 240 pixels
Display aspect ratio                     : 4:3
Frame rate                               : 23.976 (24000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 0.928
Stream size                              : 1.21 GiB (95%)

Audio
ID                                       : 1
Format                                   : MPEG Audio
Format version                           : Version 1
Format profile                           : Layer 3
Mode                                     : Joint stereo
Mode extension                           : MS Stereo
Codec ID                                 : 55
Codec ID/Hint                            : MP3
Duration                                 : 1 h 41 min
Bit rate mode                            : Constant
Bit rate                                 : 80.0 kb/s
Channel(s)                               : 2 channels
Sampling rate                            : 48.0 kHz
Compression mode                         : Lossy
Stream size                              : 58.2 MiB (4%)
Alignment                                : Split accross interleaves
Interleave, duration                     : 42  ms (1.00 video frame)
Interleave, preload duration             : 500  ms

[netmask56]

I generally use MKVToolNix for a job like this however I suspect with this source material it might be better to use Avidemux using the mkv muxer.

[ProWo]

Playing the original AVI file it's in sync?

[hello_hello]

Personally I think they way MKVToolNixGUI skips non-audio data without adding silence to compensate is rather dumb.

I'd try splitting the MKV (or AVI) as close to 00:54:26.016 as you can (probably just before). Check the audio sync for the second output file, open it in MKVToolNixGUI and resave it while applying any delay you think is required to fix the video/audio sync. It might take a few goes, but when the resaved second section is fixed, you should be able to append it to the first section again. If there's important audio happening where it loses sync there might be a noticeable "glitch" in the Audio/Video sync after rejoining the files, but if that section of the audio is mainly silence it should work fine. It depends how close to it you can split the MKV etc.

[koberulz]

I was able to fix the last one of these by demuxing with ffmpeg, then muxing the individual streams with toolnix, but this one isn't behaving as nicely.