Using freerunner as webcam display

Alexander Lehner lehner at
Fri Sep 3 21:40:36 CEST 2010

On Fri, 3 Sep 2010, Gennady Kupava wrote:

> ? ???, 03/09/2010 ? 19:03 +0200, Alexander Lehner ?????:
>> I think it's the CPU which is around 90% already at 2fps.
>> Another problem is, that the mpeg stream sometimes seems to be corrupt 
>> which crashess mplayer after some time.
>> So I did a 'while true; do mplayer...; done' around and set codecs and 
>> other parameters by hand to avoid the autodetection.
> Hey, do not scarify this man with timings, theora, omhacks and etc. I
> can play  640*480 mpeg2 at 12fps, glamo can update 640x480 fullscreen at
> much higher fps ;)
> 2 fps is way too low, you should find what is missing.
> What is resolution? what is codec, can you rstp service send in
> different format (may be mpeg4 will be faster)? Do you sending sound
> with your image? Which part of system eats 90% of CPU?
> Caclulate your rate and find out why it is so slow, find out why it is
> so slow!

I turned back the fps of the cam to 10fps and it still works, i.e. I don't 
have framedrops and CPU load is the same (ok, there is not much room 
BUT: the reaction is too slow. If i move the cam, it takes up to 15 
seconds, until the actual image appears.
It seems that there is some data stuck somewhere, but I don't know where.
If I watch the cam from a PC, I don't see that delay.

The webcam sends a sound, but i've turned sound off in mplayer.
The resolution is 640x480.
It's mplayer itself which eats all CPU.
The only alternative is MJPEG which does not work, so I'm using MPEG4 (did 
I say MPEG2 before?).
My FR is connected via WiFi (someone said it's faster than USB) and next 
to the accesspoint.

My mplayer line looks like:
mplayer -vc ffodivx -vf scale -fps 2 -fs -nosound -vf rotate=2 -vo fbdev rtsp://doorspy:554/mpeg4

And that's what mplayer says:
Playing rtsp://doorspy:554/mpeg4.
Resolving doorspy for AF_INET...
Connecting to server doorspy[]: 554...
rtsp_session: unsupported RTSP server. Server type is 'unknown'.
STREAM_LIVE555, URL: rtsp://doorspy:554/mpeg4
Stream not seekable!
  file format detected.
Initiated "video/MP4V-ES" RTP subsession on port 53728
Initiated "audio/PCMU" RTP subsession on port 58282
VIDEO:  [mp4v]  0x0  0bpp  0.000 fps    0.0 kbps ( 0.0 kbyte/s)
Opening video filter: [rotate=2]
Forced video codec: ffodivx
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
Selected video codec: [ffodivx] vfm: ffmpeg (FFmpeg MPEG-4)
Audio: no sound
FPS forced to be 2.000  (ftime: 0.500).
Starting playback...
Could not find matching colorspace - retrying with -vf scale...
Opening video filter: [scale]
Movie-Aspect is 1.33:1 - prescaling to correct movie aspect.
[swscaler @ 0x40e90890]No accelerated colorspace conversion found from yuv420p to rgb565le.



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