[XviD-devel] little image error?
Michael Militzer
michael at xvid.org
Wed Mar 17 14:10:09 CET 2004
Hi,
Quoting Christoph Nägeli <chn at kbw.ch>:
> I got some little blocks in the encoded movie that seem to have a wrong
> color.
> I first thought that my altivec code is buggy but using plain c, these
> blocks have the wrong color, too.
>
>
> Can someone have a look at the picture and tell me if I'm right?
>
> The picture can be seen at:
> http://people.ee.ethz.ch/~naegelic/Error.jpg
This looks like something related to quantization or coefficient clamping.
I'd try the following (in addition to what Christoph already suggested):
- Compile without optimizations and then try again
- If you have trellis enabled, try without trellis
- If you used h.263 quant, try MPEG or vice-versa
- If you've used a custom MPEG matrix, try with the default one
- Make sure that your c-code actually is a vanilla rc3 copy (I often
believe I have an unmodified copy but simply forgot about a 'trivial'
change I made earlier...)
BTW: How are you _decoding_ the video. Make sure you use XviD and not
ffmpeg, make sure that the decoder also only uses c-code...
Michael
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