On Fri, Nov 24, 2006 at 11:08:20AM +0100, Linetec wrote: > ... > > > Example of the render pipe command: > > > yuvcorrect -v 0 -T INTERLACED_BOTTOM_FIRST | mpeg2enc -M 2 -v 0 -r 32 -4 > > > 1 -2 1 -D 10 -g 15 -G 15 -q 5 -b 9600 -f 8 -o % > > > > For one thing you could speed up the coding by deleting the "-r 32". > > That is past the point of diminishing returns - i.e. you gain almost > > nothing over the default "-r 16" but the encoding time is longer. > > > > I'm curious why 'yuvcorrect' is being used. DV is always bottom > > field first - is something earlier in the pipeline mangling the > > field order tag? > > Well, as I'm not too experienced yet (did I mention that already? :-), I > started out by simply copying the pipe command from someone else who > claimed that this would yield the best results. And indeed I did find a > noticeable improvement when compared to the basic mpeg2enc -f 8 command. > However, I *did* look up the man pages to see what each of these > commands and options does.
I'm probably the guy who advised you to use that syntax. On the Cinelerra mailing-list, there're often people who even don't know how to export to mpeg2 while being able to specify the mpeg2enc options. Anyway, -r 32 is for sure really high. However, users want in 99.99% of cases the *BEST* quality. Hence the -r 32, even if -r 16 is sufficient IMO. As regards to the "yuvcorrect -v 0 -T INTERLACED_BOTTOM_FIRST", I added it because of a bug in Cinelerra, where the field order wasn't properly set when using the batch rendering feature of Cinelerra. In "normal rendering", it's not necessary. > > -M is either useless (no speed gain) or worse (subtle threading > > race can trigger an assert() error). > > I'm working on an AMD64 dual-core machine, and -M 2 (actually the only > option I came up with myself) results in an overall speed gain of up to > 40%. For SMP machines, the -M option is really a must... > > And 9600 is too high for a bitrate value. Try 8800 or even a little > > lower. > > [snip lots of excellent explanation] I'll modify the command line and put 8600 instead of 9600. ;-) > ... Nicolas. ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Mjpeg-users mailing list Mjpeg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mjpeg-users
