[FFmpeg-user] Concatenating video cuts - audio gets out of sync...

Bo Berglund bo.berglund at gmail.com
Wed Dec 15 15:14:40 EET 2021

On Wed, 15 Dec 2021 13:45:13 +0100, Michael Koch <astroelectronic at t-online.de>

>You could remove -c copy, but that makes the process much slower.
>Are you sure that all input videos have the same properties? Same size, 
>video codec, framerate, audio codec, number of audio tracks, audio 
>sample rate?

They are downloaded using the same ffmpeg download command which sets the video
size to 480p, like this (variables are set appropriately in the script):

ffmpeg -hide_banner -referer \"${VIDEOURL}\" -i \"${VIDEOSTR}\" -vf
scale=w=-4:h=480 -c:v libx264 -preset fast -crf 26 -c:a copy -t ${CAPTURETIME}

Then I use a tool I have created to extract the clips from these downloads and
paste them together. This has always worked.

Sometimes I need to join two clips from the same source but downloaded on
different computers using the same download script.

This is when I see this problem (but only sometimes)...

I have been able to paste clips from these downloads earlier but since it failed
today I thought that there might be a better ffmpeg command to do it..

Maybe the download script should have some specific command to handle the audio
The VIDEOSTR variable refers to an m3u8 stream URL.

Bo Berglund
Developer in Sweden

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