Hi, 0n 06/06/[EMAIL PROTECTED]:03 luukes told me:
> Am Mittwoch, 14. Juni 2006 09:42 schrieb Francesco Romani: > > On Tue, 13 Jun 2006 23:30:40 +0200 > > > > luukes <[EMAIL PROTECTED]> wrote: > > > hello! > > > i have a haupauge pvr 150 which has an mpeg2-encoder and i want > > > to process the incoming mpeg2 stream. > > > > > > if i do > > > # cat /dev/video0 > test.mpg > > > # transcode -x mpeg2,null -i test.mpg -k -g 720x576 -f 25,3 -y > > > yuv4mpeg,null ... > > > everything works. > > > > > > but i don't want to write a huge file to disk, i want > > > to read from the device (or from a pipe). > > > # transcode -x mpeg2,null -i /dev/video0 -k -g 720x576 -f 25,3 -y > > > yuv4mpeg,null ... > > > then many parts of the picture are destroyed (mainly on the right side) > > > but some parts are ok. > > > > [...] > > > > Mi first thought is that seeking will be disruptive in such kind of > > streams. So, try adding -H 0 to disable probing, hopefully it should help. > > > > Best regards, > > finally i found out that the kernel-module of my caputre-card says > > linux kernel: ivtv0: All encoder MPEG stream buffers are full. Dropping data. > linux kernel: ivtv0: Cause: the application is not reading fast enough. > > so this causes the errors in the picture. of course > # cat /dev/video0 > test.mpg > reads fast enough. > > it seems that reading from the device is slower than from a file. You have to cope that 25 fps go through transcode. AFAIK yuv4mpeg isn't that CPU expensive and if your "..." don't include some expensive -J extentions the CPU should cover it. OTOH yuv4mpeg does produce real big files IIRC, so probably i/o might be the bottleneck. For my old Bt878, there there is a module parameter to increase buffers (IIRC ?gbuffers?). I am not familiar with PVR/ivtv, but probably there is something similar. <brainDump> mkfifo /tmp/mpeg; cat /dev/video0 | /tmp/mpeg; transcode -i /tmp/mpeg playing with transcodes -u IIRC for a similar problem some months/years back Erik Slagter posted a program called (?super-buffer/pipe?) which could be of assistance. </brainDump> -- bye maik
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