On Sun, 17 Aug 2003, Alexei Dets wrote:
> BTW, if you want maximum quality you should not run mpeg2enc with default
> settings - increase -r (-r 24, -r 32) and set -4 -2 to 1 (-4 1 -2 1).
> Warning: these settings will make your encoding SLOW. Default settings is a
-4 1 almost doubles the amount of time needed to encode and the
savings are very small (perhaps 1 or 2% maximum). Usually it is
not worth the extra time.
I have not tried (yet ;)) changing the search radius from the
default (which is 16) to 24 to the encoder (I do use -r 24 with
yuvdenoise though). That is something to try on the next set of
encodings.
> compromise between speed & quality. Also it is possible to play with -N, -H
> and different quantization matrices: tmpgenc & kvcd matrices can give you
> significantly better compression (so you can decrease -q and get a better
> quality for the same file size).
Definitely yes! The movies look very good using "-K kvcd -q 4",
no need in many cases to use -N at all with the new matrices (but
you can use -N and -K/-H together if desired).
A couple things that might be worth mentioning again for folks who
are using the 'smilutils' to convert the DV to YUV4MPEG2...
1) Build the smilutils using FFMPEG's libavcodec routines. Using
the DV decoder in libavcodec was good for about a 5% reduction
in the average bitrate of the final movie.
2) Do any median and denoise filtering in the 4:1:1 colorspace
by using "smil2yuv -i 2", then convert to 4:2:0 using y4mscaler
just before sending the data into the encoder. This improves
the bitrate by several more percent.
> And CVS version provides better quality compared to 1.6.1 with the same
> settings (thanks to Steven to convince me :-).
Hopefully it was the picture quality that also helped to convince
you :)
Cheers,
Steven Schultz
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