hello Am Samstag, 17. Juni 2006 11:26 schrieb Maik Holtkamp: > 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.
i'm using filters but it's the same problem without them. my P4 2,8GHz needs 10-20% so this should not be the problem. > OTOH yuv4mpeg does produce real big files IIRC, so probably i/o > might be the bottleneck. i thought of that too - if not the CPU it's maybe i/o. but i don't produce large files because i use pipes. > 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. will check that. > <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> i found many posts of Erik but no super-buffer/pipe. thanks for the hints lukas
