[FFmpeg-devel] [PATCH]Flip zerocodec

Derek Buitenhuis derek.buitenhuis at gmail.com
Sat Dec 1 19:40:21 CET 2012

On 01/12/2012 1:15 PM, Reimar Döffinger wrote:
> 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?

Yes, I tested XP and 7. IIRC, there is no guarantee about which orientation
the codec will recieve.

>>>> 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".

Maybe not. ZeroCodec was written in the XP era, so one could argue that is the "most
correct" behavior. Shrug.

- Derek

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