MPEG1 is technically limited to about 1800Kb/s for DVD use. I forget exactly where I saw that but I know that DVD Studio Pro3 imposes that limit.
Thanks for the info!
The point is moot though since at 352x288/240 ~1Mb/s is more than sufficient.
mpeg2enc -v 0 -f 0 -F 3 -n p -a 2 -b 1875 -I 0 -r 16 -q 8 -V 224 -g 9 -G 15 -N -S 4000 -B 230
~1000 kb/s may be enough for 352x288/240 but my string above needs some tweaking for decent output.
I ran a series with -b 1875 and different -q values (8, 6, 4, 2, 1, and q omitted):
The moving scenes were OK but dimly lit or quiet scenes were quite bad with -q 8. -q 1-2 and no q (=CBR) were the best in this regard. I found that -q 4 was the best compromise if I wanted to use VBR at all (the calculations how to fill a DVD are easier with CBR...).
I also analyzed the different -q output bitrates with the demo version of Digigami MegaPEG.X (Mac OS X) and Bitrate Viewer (via Virtual PC) and got similar results: with -q 8 there was a HUGE drop in the bitrate in the quiet scenes -- with -q 4 the drop was moderate and with -q 1-2 almost nonexistent. Omitting -q was CBR, as expected.
<http://www.sjoki.uta.fi/~shmhav/SVCD_on_a_Macintosh.html#Other_tools>
Fiddling with -N high frequency filter might be useful, too.
When I need to create a DVD with extended play time I use the MPEG-2 and the 1/2 D1 (sometimes called "CVD") frame size of 352x480/576 That's a very good compromise between the "VCD" size where 3/4 of the information is being tossed away (704->352 and 480 -> 240 basically is losing 3/4 of the information). With 352x480/576 less is being discarded. And yes, 352x480/576 is a valid DVD frame size that all DVD players have to accept ;)
Yes, Half-D1 is my low bitrate (~3750 kb/s) favorite, too, because it allows interlaced output. I dislike those jerky pans that progressive output gives.
p.s. I recently ran a test with commercial MPEG encoder demos for Mac OS X and liked MainConcept MPEG Encoder the best. BitVice Lite was also OK with a decent price. Digigami MegaPEG.X Batch and Digigami MegaPEG.X QT's default settings were WAY too smooth and fuzzy for my taste but adjusting the settings provided decent output. Digigami MegaPEG.X Batch's bitrate and quantization chart is a very nice feature. LaCie FastCoder (HW encoder) currently supports only NTSC. iDVD 4-5 are IMO very good, but the customizations options for resolution and bitrate are minimal (CBR ~7.3 Mb/s or VBR ~3.1-5.8 Mb/s based on content length). AFAIK Apple's Compressor (bundled with DVDSP and FCP) uses the same encoder engine as iDVD but it has more options for tweaking.
<http://www.mainconcept.com/mpeg_macencoder.shtml>
<http://www.sjoki.uta.fi/~shmhav/SVCD_on_a_Macintosh.html#Encode>
-- Matti Haveri <[EMAIL PROTECTED]> <http://www.sjoki.uta.fi/~shmhav/>
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