On Sat, 22 Feb 2003 16:23:55 -0500 D Richard Felker III <dalias@aerifal.cx> wrote:
It does!! 0.27 is a fairly large difference in PSNR!!
Hmm.. Interesting. Then PSNR behaves totaly different from what i am used of SNRs (mostly "normal" signals for digital transmission). But, then would be the encoding with the lower quantisizers the worse one ?
BTW, you should try with vqscale=2 on the first pass and see if that works well, rather than vqscale=5. The latter will encode the whole first pass at very low quality so it probably won't estimate complexity well.
I did it and got folowing result: --- 1.pass: vqscale=2 / 2.pass: vbitrate=615 1.pass: -oac copy -ovc lavc -lavcopts vcodec=mpeg4:vpass=1:vbitrate=615:vqscale=2 2.pass: -oac copy -ovc lavc -lavcopts vcodec=mpeg4:vpass=1:vbitrate=615 Video stream: 615.134 kbit/s (76891 bps) size: 381105923 bytes 4956.394 secs 118836 frames Audio stream: 128.000 kbit/s (15999 bps) size: 79295296 bytes 4955.956 secs PSNR: Y:44.34, Cb:47.23, Cr:47.96, All:45.17 --- Which makes it slightly better then the 1.pass: vbitrate=615 / 2.pass: vbitrate=615 case. The maximal quantisizer values are between the two others (ie, it's not allways max=4 but not as often at max=5) Though, i cant see any difference in quality between the three encodings. Attila Kinali -- Emacs ist für mich kein Editor. Für mich ist das genau das gleiche, als wenn ich nach einem Fahrrad (für die Sonntagbrötchen) frage und einen pangalaktischen Raumkreuzer mit 10 km Gesamtlänge bekomme. Ich weiß nicht, was ich damit soll. -- Frank Klemm, de.comp.os.unix.discussion