[FFmpeg-user] screen capture - small files

Moritz Barsnick barsnick at gmx.net
Wed Nov 25 15:06:37 CET 2015

On Wed, Nov 25, 2015 at 12:01:00 +0100, Jesper Hedin wrote:
> ffmpeg  -t 5 -f avfoundation -i "1:0" -pixel_format nv12 -c:v mpeg4 -c:a aac -strict -2 -framerate 3 -r 3  -b:v 1024  -ac 1 -sample_rate 22050 outfile.mp4

> However, it is not quite there yet. What I am missing is audio played
> normally over a video that plays in 3 fps. With the above command all
> audio seems to be captured at ”3fps” and then played much faster,
> like 24 fps or whatever. Anyway, the audio plays quickly in the
> beginning and then silence.

"-framerate" is an input option, it needs to be specified before the
"-i" it refers to. And if that works correctly (i.e. avfoundation
actually delivers 3 fps), you don't need the output option "-r 3".

"-sample_rate" is also an input option, but not for avfoundation. For
the output, you need to specify "-ar".

Again: showing us your command line AND complete, uncut console output
would be *extremely* helpful in pinpointing these issues, as ffmpeg
(most often) clearly says what it is doing.


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