Out of synch audio durig alternate audio track

loninapleton · 9th June 2021, 03:29

Often I use a program called Levelator II where spoken word is
of primary importance such as live stage drama.

Remuxing with an alternate track from the original often introduces out of synch.

I know the tools in VLC to advance or recede the audio. But I cannot _see_ what is happening accurately. Even hit and miss forward and back I cannot land on synch with the manual method.

MediaInfo sometimes shows a delay in text view or not.

Another difficulty to look at this numerically-- total file length -- appear
to be nearly identical. In other words .783 vs .786 or something similar.

What is any tool to get this right with mkv video?

tebasuna51 · 9th June 2021, 10:16

Most the times the out of sync when remux a video with an audio modified from the original it is not a problem of the modified audio.

Check in MediaInfo if the video is VFR (Variable Frame Rate), if it is you must extract the video TimeStamps and apply them to the next remux.

mkvextract "INPUT.mkv" timestamps_v2 0:"TIMESTAMPS.txt"

[EDIT] Don't worry about a little size difference, wav files can have info extra chunks than not change the data.
Check both in MediaInfo, or explain how do you obtain the input file (ffmpeg can add usseless extra chunks)

9th June 2021, 03:29	#1 \| Link
loninapleton Registered User Join Date: Jun 2019 Posts: 60	Out of synch audio durig alternate audio track Often I use a program called Levelator II where spoken word is of primary importance such as live stage drama. Remuxing with an alternate track from the original often introduces out of synch. I know the tools in VLC to advance or recede the audio. But I cannot _see_ what is happening accurately. Even hit and miss forward and back I cannot land on synch with the manual method. MediaInfo sometimes shows a delay in text view or not. Another difficulty to look at this numerically-- total file length -- appear to be nearly identical. In other words .783 vs .786 or something similar. What is any tool to get this right with mkv video?

9th June 2021, 10:16	#2 \| Link
tebasuna51 Moderator Join Date: Feb 2005 Location: Spain Posts: 6,915	Most the times the out of sync when remux a video with an audio modified from the original it is not a problem of the modified audio. Check in MediaInfo if the video is VFR (Variable Frame Rate), if it is you must extract the video TimeStamps and apply them to the next remux. mkvextract "INPUT.mkv" timestamps_v2 0:"TIMESTAMPS.txt" [EDIT] Don't worry about a little size difference, wav files can have info extra chunks than not change the data. Check both in MediaInfo, or explain how do you obtain the input file (ffmpeg can add usseless extra chunks) __________________ BeHappy, AviSynth audio transcoder. Last edited by tebasuna51; 9th June 2021 at 10:39.