[FFmpeg-user] fast video codec for screen casting

dE . de.techno at gmail.com
Wed Jan 4 10:19:14 CET 2012

On 01/04/12 17:29, Carl Eugen Hoyos wrote:
> dE .<de.techno<at>  gmail.com>  writes:
>> I know libx264 with -preset ultrafast -threads 2/4/8..., but it gives
>> FPS of 18 only.
>> (ATI card  ).
> I am not sure I understand but are you trying to imply that the speed cannot be
> improved, no matter which encoder you try?

No. If I use rawvideo, FPS are ok, but it takes too much i/o; so it's 
not an option.

>> Raw video is too heavy for i/o... so it's not an option.
>> So, do we have an intermediate way? Larger files but good FPS (with same
>> quality).
> What did you try?
> How fast is -vcodec mpeg1video? -f null?
> Carl Eugen

I tried

ffmpeg -f alsa -i default -f x11grab -s 1280x800 -i :0.0 -threads 8 
-preset ultrafast -b 20000k -vcodec libx264 -ar 44100 -ac 2.0 -acodec 
pcm_s16le out.avi

Now I tried -

ffmpeg -f alsa -i default -f x11grab -s 1280x800 -i :0.0 -threads 8 -b 
20000k -vcodec mpeg1video -ar 44100 -ac 2.0 -acodec pcm_s16le out.avi

The output is corrupt and FPS is ~15 FPS, setting -f to null results in 
error -- unknown format null.

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