Re: [MEncoder-users] Cannot achieve better picture quality with MPEG2 - help needed

Corey Hickey wrote:
> This appears to be an effect of the colorspace conversion from BGRA to
> YV12. -sws 8 appears to produce more even banding. You can try the
> different scalers yourself. For example:
>
> $ mplayer gradient.avi -vf scale=720:480,format=yv12 -sws 8
>
> -Corey
>
>

I've uploaded another PSD comparison to

ftp://upload.mplayerhq.hu/MPlayer/incoming/

The file is called: rgb24_vs_rgb32.psd

It seems as though the colorspace conversion is a part of the problem.
If I use a rgb24 source (FFV1 file) instead of the rgb32 source, the
colors are more accurate. I've broken the PSD file into several layers
to show screenshots of the same gradient. If you look at all of the
samples (rgb32 vs rgb24), the green in the upper left corner of the
frame is much closer to the original in the rgb24 samples (perceptually,
the colors are better everywhere in the rgb24 screenshots). A quick
test with ffmpeg reveals that the same problem (inaccurate colors with
rgb32 source) exists in ffmpeg. Is this a bug? If not, how can it be
explained/fixed?

Now, the secondary issues is the complexity of the banding. In all of
the rgb32 screenshots, the banding is more complex (retains more
detail??) than the rgb24 screenshots. Can I improve the complexity of
the banding with the rgb24 source? Is this another symptom of the
colorspace conversion???

Your help is much appreciated. Thanks!!!

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