(MKV) Audio/Video synching problems after remuxing the same files I demuxed

[Sigma X Virus]

I have this MKV video that has two audio tracks. I didn't need one of these, so I demuxed the file (MKVextract), and remuxed with MKVmerge using the video track and the audio track I wanted to leave. Checked no other options, the program gave me no warnings. Strangely, the audio is the same but the video track is off-synched, ending several seconds before.

I used MediaInfo to check both MKVs, the before and the after, and saw no differences except for bitrate.

GENERAL INFO for the source
Complete name : C:\Users\Sigma X Virus\Videos\07_31_2004.mkv
Format : Matroska
File size : 237 MiB
Duration : 23mn 54s
Overall bit rate : 1383 Kbps
Encoded date : UTC 2004-08-13 20:31:49
Writing application : mkvmerge v0.9.2 built on Jun 29 2004 23:48:14
Writing library : libebml v0.7.0 + libmatroska v0.7.0

GENERAL INFO for the faulty file
Complete name : C:\Users\Sigma X Virus\Videos\07_31_2004english.mkv
Format : Matroska
File size : 221 MiB
Duration : 23mn 54s
Overall bit rate : 1291 Kbps
Encoded date : UTC 2009-02-09 13:27:18
Writing application : mkvmerge v2.4.0 ('Fumbling Towards Ecstasy') built on Oct 11 2008 20:13:15
Writing library : libebml v0.7.7 + libmatroska v0.8.1

VIDEO INFO (same for both files)
Format : MPEG-4 Visual
Format profile : Streaming Video@L1
Format settings, BVOP : Yes
Format settings, QPel : No
Format settings, GMC : No warppoints
Format settings, Matrix : Default
Codec ID : XVID
Codec ID/Hint : XviD
Duration : 23mn 53s
Width : 640 pixels
Height : 480 pixels
Display aspect ratio : 4/3
Frame rate : 29.970 fps
Resolution : 8 bits
Colorimetry : 4:2:0
Scan type : Progressive
Writing library : XviD 1.0.1 (UTC 2004-06-05)

AUDIO (both tracks had the same info, both files give the same info)
Format : Vorbis
Codec ID : A_VORBIS
Duration : 23mn 54s
Bit rate mode : Variable
Channel(s) : 2 channels
Sampling rate : 48.0 KHz

What I'm doing wrong?

[poisondeathray]

did you forget to set the fps? when muxing raw video tracks, mkvmerge assumes 25

a better way is to use mkvmergegui on the original file, uncheckmark the unwanted audio track (instead of using mkvextract), make a new .mkv

[Sigma X Virus]

[s:08f8aedb14]I couldn't, that happened when I muxed H264 tracks, this was an XVID track and the FPS field was in gray. Besides, if you look at the info I posted, MediaInfo read both files as having 29.970 fps.

Maybe I should try muxing to AVI. I dunno, just for kicks, maybe it will work. (But I don't know how to do it)[/s:08f8aedb14]

Disregard that, I aspirate male chickens.

Remuxing the source file and unchecking the unwanted track worked like a charm. Thanks.

[poisondeathray]

When you extract it, the media delay (if any) is not included. You can find the media delay in eac3to on the original .mkv, for example, and when re-muxing enter the delay value

An easier way is the 2nd method I suggeted earlier, because there is no extraction. Only the 2nd audio track is removed, and everything should be in sync. Did you try it?

You can use avimux-gui to create an .avi if you want.