[theora-dev] libtheora alpha 2 release

Ralph Giles giles at xiph.org
Mon Jun 9 16:26:56 PDT 2003



On Monday, June 9, 2003, at 11:49 pm, Mike Melanson wrote:

> 	I must have missed something here. Which different colorspaces are
> available?

Currently only three: ITU Rec 601, CIE 709 (now also an ITU spec), and 
'not specified'. And all still mean YUV 4:2:0 or 4:1:1, so it's not a 
new colorspace in the sense of CMYK or RGB.

The idea is to have a flag indicating one of only a handful of the most 
common, so that players can attempt to do color conversion for whatever 
device they're driving without huge additional complexity. The example 
player just prints out the value of the flag. Likewise, an encoder 
should pick the closest colorspace to what it's given as input and 
convert (if necessary) to one of the supported options.

This was a compromise between the traditional 'hope for the best' no 
specification at all, an the kitchen-sink approach taken by (for 
example) H.264.

cheers,
  -r

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