[MPlayer-users] QT Cinepak Decoding

[Mike Melanson]

On Tue, 23 Oct 2001, Arpi wrote:

> you only have to call your codec from dec_audio.c or dec_video.c.
> the only thing you have to implement is init and decode frame functions,
> and optinally sync and skip frame for seeking. it's very easy.

	Okay, I just took a brief tour through the code and I see where I
would drop in the new init() and decode() routines. I'm guessing that I
would also need to add VFM_CVID to the codebase and also do some other
type of initialization so that the switch variable gets set to VFM_CVID in
the first place, right?

> the preferred output of video codecs is YV12 planes (provide 3 char* pointer
> to Y,U,V planes and bytes_per_line values of the 3 planes) and 16-bit
> mono/stereo of audio codecs, but any other formats are accepted.

	Sounds simple enough, though Cinepak uses a "simplified" YUV
format, which is laid out like YV12, only entirely integer-based so that
conversion to RGB space is done completely with simple add/subtract and
bit shifts. But I think it's okay to output that into a YV12 space. Then
there's Sorenson; it apparently uses YVU9. How does that fit into the
existing color spaces?

	BTW, as a warmup, we should implement Microsoft's Video-1 (fourcc
of 'CRAM' or 'WHAM', outputs RGB555 data). It's exceptionally simple and I
think it would be nice to see an excellent media player like MPlayer move
to as many open source decoders as possible.

	-Mike Melanson