Hi Steven, On Sat, 14 Aug 2004 22:17:04 -0700 (PDT), Steven M. Schultz said:
[...] > > cat stream.yuv | mpeg2enc -q 3 -b 8500 -f 8 -o movie_new.m2v > > Fine, but 8500 might be a bit high especially with -q 3. What does > mplex say is the peak bitrate? It's not necessary to have an audio > track - something like "mplex -f 8 -o /dev/null movie_new.m2v" will > give the statistics. I don't know yet, what mplex will say. Till now I haven't encoded the whole movie, only the first seconds for testing purposes. But the beginning seems to work with mplex: INFO: [mplex] Peak bit-rate : 8694400 bits/sec If I interpret the output of mpeg2enc correctly, the quantizer is much higher anyway: INFO: [lt-mpeg2enc] Frame end 1482 P quant=8.36 total act=62902.65854 Only the beginning with a static picture is really quant=3. [...] > Are you using the cvs version or the release (1.6.2 I believe) version? I'm using 1.6.2. [...] > You can determine if this is the problem by adding the option > "--no-dualprime-mpeg2" to the mpeg2enc command. The CVS version has Hmpf, my 1.6.2 doesn't know about this option. Even "strings" cannot find the string in the binary. Therefore I just compiled the CVS version. However, the results do not look different, even if I use the above option with the CVS mpeg2enc. [...] > The other possibility is that you're driving the DCT/iDCT into overflow > with -q 3. Does the artifacting go away if you use "-q 4"? That seems to have been the case. If I use "-q 4", the artifacts seem to go away. :-) Thanks for this tip. [...] > mpeg2dec -o pgmpipe movie.m2v | pgmtoy4m -i t -r 30000:1001 -a 10:11 | \ > mpeg2enc -q ... -o movie_new.m2v > > You may need to change the '-i t' to be '-i b' if the video is > from DV (which is always bottom field first0 and the rate (-r) to be > 25:1 for PAL, and so on. Great. So for my PAL DV material I use "pgmtoy4m -i b -r 25:1 -a 3:4". Having hopefully settled this "error" I can now turn my attention to my second problem: Interlacing (I've come to loathe it). I've tried bottom- and top-first encoding but the DVD player just keeps on showing very jerky motions. Either it thinks that it is a progressive stream or it uses a wrong field order, but sadly the player doesn't support the "-v" flag. ;-) I will have to see if my newly encoded movie works better. Ciao Florian PS: Is the CVS mpeg2enc version quicker than the 1.6.2 release? I'm noticing encoding speedups around 50%. That's great. :-)
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