[FFmpeg-user] audio is too short

Michael Koch astroelectronic at t-online.de
Wed Feb 26 21:04:03 EET 2020

Am 26.02.2020 um 16:48 schrieb Michael Koch:
> Hi,
> I'd like to know if someone can reproduce this problem:
> Make a 6s video with audio:
> ffmpeg -f lavfi -i testsrc2=size=vga -f lavfi -i sine=1000 -t 6 -y 
> video.mp4
> The video plays correctly and has 6s of audio.
> Now mix the audio channels from two of these input videos:
> ffmpeg -i video.mp4 -i video.mp4 -lavfi "[0:a][1:a]amix=weights='1.0 
> 0.1'" -y out.mp4
> You can hear that the audio from the first input ends too early at 4s, 
> and the audio from the second input has the correct length 6s.
> Tested with FFplay and VLC.
> Known workaround: add -c:v mpeg4
> This is ticket 8489, but so far nobody did have a look at it.

Another workaround is to pad a single audio sample to the end of the 
first input:
ffmpeg -i video.mp4 -i video.mp4 -lavfi 
"[0:a]apad=pad_len=1[p];[p][1:a]amix=weights='1.0 0.1'" -y out.mp4


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