[FFmpeg-devel] [PATCH]Flip zerocodec

Reimar Döffinger Reimar.Doeffinger at gmx.de
Sat Dec 1 19:15:55 CET 2012

On Sat, Dec 01, 2012 at 12:54:10PM -0500, Derek Buitenhuis wrote:
> On 01/12/2012 10:57 AM, Reimar Döffinger wrote:
> >> Patch is wrong. The problem has nothing to do with ZeroCodec really.
> >>
> >> The way several VFW codecs signal bottup-up RGB is to use a negative height.
> > 
> > No, bottom-up is the default Windows bitmap format.
> > It signals usage of non-default layout (i.e. not bottom-up) by negative
> > height.
> Whether the VFW codec (ZeroCodec) gets bottom-up RGB depends on the OS, last time I tested.

Could you explain? Since VFW exists only for Windows, do you mean it
depends on the Windows version? If yes, do you know with which version
behaviour changed?

> >> Furthermore, depending on which OS is used to decode or encode ZeroCodec, it
> >> will be flagged correctly or incorrectly, and may or may not be bottum-up RGB.
> > 
> > For AVI we generally consider whatever WMP does as correct...
> The original ZeroCodec binary is buggy. It will encode/decode differently on different
> OSes. There is *no* correct behavior. It is simply not possible.

Well, going with whatever the latest version of WMP does seems reasonable
to define as "correct".

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