D Richard Felker III
dalias at aerifal.cx
Sat Apr 3 06:14:38 CEST 2004
On Fri, Apr 02, 2004 at 10:25:50AM -0800, Loren Merritt wrote:
> The reason (I infer) that XviD can fill any desired bitrate, and lavc
> can't, is that XviD supports quantizer 1 (-xvidencopts
> min_iquant=1:min_pquant=1). lavc has a vqscale=1 (constant quantizer), but
> doesn't respect vqmin=1 in 2-pass encodes.
You need lmin too. Then it should work fine.
> Despite what the lavc entry in the manpage says about quant 1 making
> little quality difference, XviD with min quant 1 looks much better than
> lavc when lavc maxes out with quant 2 at 800kbit/s (and I am encoding at
> unscaled dvd resolution).
If you're using 800kbit/sec, quant 1 is useless. It will just waste
more bits on frames that already look perfect and then your other
frames will get higher quantizers.
In fact, 800kbit/sec is so low for full DVD resolution, that I'd be
surprised if any quantizers come out less than 4 or 5, and most are
probably 7-9 or higher!
The key to good quality is proper cropping and scaling, not using full
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