On Tue, 26 Aug 2003, Ray Cole wrote:
> I found the answer... This newer version of mpeg2enc forces variable bit
> rate from what I can tell, whereas the older one did not (I'm not sure
> if 1.6.1 actually turned variable bit rate on before and I commented it
> out or if it came that way...but nevertheless I see it commented out in
ALL previous versions that could generate DVD compatible streams
were VBR
> I prefer CBR so I can predict the size of the DVD, and at least with the
> older mpeg2enc I could never get VBR to play right in my DVD player
> whereas CBR played just fine. I like the way everything looks and works
> today so I'm not inclined to try VBR :-) And I also believe that it
No sense of adventure, eh? ;) There _were_ issues in earlier
releases, now that the bugs have been fixed it's stay with the
broken approach?
I've made hundreds of DVDs using the VBR logic and they all
play fine on a variety of standalone players ranging from an
old Audiovox portable to a Philips (which will play anything it
seems).
> wasn't necessary 4x slower now - maybe 2x. The reason it appeared 4x
> slower was because when I was running mplayer on the .m2v as it was
Ah, that'll do it - MPlayer does use a lot of cpu (sure seems to
use more than Ogle for playing DVDs - at least on my systems).
My suspicion is that MPlayer was interfering more than was
realized. The current encoder hasn't slowed down by 2x on
the systems I use - but then they're all dual cpu systems so
the filtering doesn't slow down the encoder too much.
> Any thought to making CBR an option in mpeg2enc for DVD formats rather than
> forcing VBR?
Ick - that means scenes that need more bits will be starved and
not look good while other scenes that don't need bit will waste
them. All for making it easy to calculate the size?
Why not use the '-b' bitrate as an upper bound and calculate
according to that - if the project comes in smaller that's not
a Bad Thing, I frequently use the extra space to put scans of
the artwork, and so on onto the disc.
Any player that can't handle VBR is busted/broken (and hopefully
within the return period so the money can be refunded ;)).
All commercial DVDs that I've seen are VBR. The commercial
DVD makers use that to get as much as possible on a DVD without
having to cut the bitrate down to poor quality levels.
But there's no need for making CBR an option - it's already there.
If you really want poorer quality then leave off the -q option -
that is what tells the encoder to engage the VBR logic. Without
the -q the encoder will generate CBR according to the -b value
Vendors go out of their way to create VBR encoders (Apple's
touting that as one of the main features in their new encoder -
the one in Quicktime-Pro is CBR despite their claims to the
contrary) - try it, it'll generate better movies.
Steven Schultz
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