[FFmpeg-user] screen capture - small files

Jesper Hedin jesper.hedin at intaktus.se
Mon Nov 23 08:27:02 CET 2015

Hello all.

I want to use ffmpeg to capture screen and sound on a macintosh. I want the file size as small as possible, with a fps of about 3-5 and audio quality of maybe 128 kbps at most, though 64 kbps is acceptable.

This is the closest I have come:

ffmpeg  -f avfoundation -i "1:0" -c:v mpeg4 -c:a aac -strict -2 -r 3 -b:v 1024 out.mp4

It gives me a large file size and very good audio (too good/better than needed). Also a few messages appear that I don’t understand:

[avfoundation @ 0x7fc535000000] Selected pixel format (yuv420p) is not supported by the input device.
[avfoundation @ 0x7fc535000000] Supported pixel formats:
[avfoundation @ 0x7fc535000000]   uyvy422
[avfoundation @ 0x7fc535000000]   yuyv422
[avfoundation @ 0x7fc535000000]   nv12
[avfoundation @ 0x7fc535000000]   0rgb
[avfoundation @ 0x7fc535000000]   bgr0
[avfoundation @ 0x7fc535000000] Overriding selected pixel format to use uyvy422 instead.
[avfoundation @ 0x7fc535000000] Stream #0: not enough frames to estimate rate; consider increasing probesize

The pixel format used is uyvy422. If I explicitly choose it,the output becomes 

Incompatible pixel format 'uyvy422' for codec 'mpeg4', auto-selecting format ’yuv420p'


[avfoundation @ 0x7f9c24800000] Overriding selected pixel format to use uyvy422 instead.

So does anybody have a tip for me on how to use ffmpeg to achieve my goal? Thanks!


More information about the ffmpeg-user mailing list