[Ffmpeg-devel] PIX_FMT_RGB555 and alpha channel

Alex Beregszaszi alex
Mon Oct 30 02:48:06 CET 2006


> > I will elaborate.  Alex and I are implementing FLC/FLX and DTA
> > encoding  into ffmpeg.  We are a little way from having stuff ready
> > to submit, but  there is a problem with compression when the Alpha
> > bit is set in an  RGB555 pixel, for the FLX format.  It means we
> > have to mask every pixel  coming in, to take the spurious alpha bit
> > out, or that bit prevents run  length compression from being
> > effective.  The format is really wanting  to use RGB555, without
> > alpha, so that black is 0x0000 and not 0x8000 but 
> why does RLE compression not work with the alpha bit set?
> and why exactly is the alpha bit set at all? if imgconvert.c sets it,
> IMO fix imgconvert.c so it doesnt

Attached is a patch which fixes it, and adds the old behaviour as

Alex Beregszaszi | alex at fsn.hu
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