[Ffmpeg-devel] [PATCH] Fraps decoder

Mike Melanson mike
Fri May 13 22:20:29 CEST 2005

Roine Gustafsson wrote:
> No, they're not constant size. I haven't looked at the dll, only the data.
> There seems to be a frequency table stored before each plane. It's 256 
> frequencies that has the 'bell' form; therefore I'm suspecting it's a 
> simple left-difference or similar.
> I tried interpreting the data planes as being canonical Huffman coded 
> difference, with the frequencies from the table, but I've not gotten 
> anything reasonable out from that.

	Hmm, this does not really reconcile with the whole "lossless" theme. 
Storing losslessly as either BGR24 or YUV420 makes sense since the game 
data can be either RGB or YUV (depending on whether the game is 
rendering 3D objects or playing a FMV file). This makes we wonder if a 
file might contain both types of data in the same file. The frame decode 
logic certainly supports it.

	-Mike Melanson

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