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

[Nicolas Hesler]

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!!!