Re: msvidc32/msvideo1 question: upside down buffers?

[Maarten Lankhorst]

Hi Joerg,

On 06-04-10 17:47, [e-mail] wrote:
> does anybody know why msvideo_decode_8bit(), when imported
> from the FFmpeg project in 2004, was changed such that the
> pixels[] array became filled upside down?  See how
> #ifdef ORIGINAL,
>    which shows the original FFmpeg code, differs from the
> #else
>    branch in msvideo1.c
>
> Do buffers in Wine work upside down and backwards?
> Why can't Wine use exactly FFmpeg's code?
>
> I'm asking because no similar set of changes was applied to
> msvideo_decode_16bit().  I have files that are rendered
> incorrectly and even suspect of crashing Wine because of
> this.  I could write a patch but need to know.

See BITMAPINFOHEADER documentation for biHeight:

http://msdn.microsoft.com/en-us/library/dd183376%28VS.85%29.aspx

However not all codecs handle negative height properly, and just ignore 
the information the sign gives. This is probably why ffmpeg puts it 
upside down internally.

Cheers,
Maarten