[FFmpeg-devel] pixel format convertion yuv422p->yuv420p->yuv411p->yuv422p degrade picture

[Maksym Veremeyenko]

Michael Niedermayer ???????(??):
> On Tue, Jul 15, 2008 at 04:22:33PM +0100, M?ns Rullg?rd wrote:
[...]
>> Without thinking a little harder, I don't know whether such a conversion
>> sequence is possible without such drift.  It will always be lossy, as I'm
>> sure you already realise.
I did cyclic test for:

  +->422->420->422->411->422-->+
  |                            |
  +----------------------------+

no visial degrades found.

> I suspect that dithering could reduce the drift, for normal interpolation
> based filters but running 50 converters in a row is a stupid thing to do.
Such condition possible in:
Uncompressed (4:2:2) -> DV25 (4:2:0) -> DVCpro25 (4:1:1) -> Uncompr

50 iterations was only for proving that convertions degrade picture...

So, as conclusion, that a normal?

-- 
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Maksym Veremeyenko