On Wed, 21 Jul 2004, Marc Gregoire wrote:
> > o Older versions of jpeg2yuv did not convert the "graphics Y'CbCr"
> > colorspace to the "video Y'CbCr" colorspace. Make sure yours
> > has the (apparently undocumented in manpage) "-R" option, and
>
> Apparently my version does not recognize the -R option.
> Where can I download the latest version (preferably for Windows).
Hmmm, if you built 1.6.2 and it does not recognize -R then that
option must have been added after the last release. You'll need to
check out the CVS version in that case.
-R is needed to make sure the chroma is in bounds but that won't fix
the quality issue that you're seeing.
> Another question: is there a way to directly convert a BMP file to YUV4MPEG
> instead of first converting that BMP to JPEG and then using jpeg2yuv?
Not that I know of. BMPs aren't a very popular format outside of
windows from what I've seen.
> > y4mscaler -I sar=1:1 -O preset=dvd -S option=sinc:6
>
>
> I scaled the images with an external program to 720x576, so no need for y4mscaler.
I'm a bit busy and will respond to the other mail items later tonight
but one thing I can say now is that I can see fringing/ringing even
in the original .jpg image. Take the original .jpg into the GIMP
and at a 2 or 4x zoom factor the distortion around the edges of the
flowers is quite visible.
mpeg2enc is merely reproducing (and due to bitrate constraints is
magnifying) the quality issue that's already present. The other
encoder, using a 3 or 4x higher bitrate is able to avoid most of the
quality loss but even there it's slightly visible.
I wonder if a higher quality resizing/scaling would help in this
case.
Cheers,
Steven Schultz
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