[FFmpeg-user] scale input video before transcoding

jacob s jacobhameiri at gmail.com
Mon Mar 12 18:36:30 CET 2012


I am using ffmpeg to stream windows XP desktop and sound ( directshow input
), but I am facing performance issues.

this is the command I am using:
-f dshow -i video='screen-capture-recorder':audio='Stereo Mix (IDT High
Definition' -vcodec  libx264 -preset ultrafast -r 10 -async 1 -ab 32k -ar
22050 -f mpegts udp://

When using this command ffmpeg uses about 65% CPU ( Pentium4 2.8 GHz ), and
after a short while I am seeing glitches in the viewing machine.

I thought of reducing CPU usage by scaling the input video to 50% - 75%,
but even after scaling to 50% CPU usage doesn't change, I suspect this is
because the scaling is performed after the transcoding process, is there a
way I can tell ffmpeg to scale the input coming from the screen capturer ?

What else can I do to reduce the glitches and CPU usage ( I already reduced
to 10 fps, I cant go any lower than that ) ?



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