[vlc-devel] [PATCH 2 of 4] avcodec: add HDYC to known ffmpeg chroma table

David Flynn davidf+nntp at woaf.net
Wed Oct 15 01:35:35 CEST 2008

On 2008-10-14, Edouard Gomez <ed.gomez at free.fr> wrote:
> +    /* The next entry for HDYC is more of a temporary hack.
> +     * UYVY conforms to the BT601 standard making its Y samples use a reduced
> +     * [16-235] range whereas HDYC conforms to the BT709 standard which makes
> +     * its Y samples use the full [0-255] range.


Rec 709 Video does not specify this.  Y'CbCr video as specified by
Rec 709 is 16-235 for Y'.

The reason for inventing a 4cc code is to refer to the different colour
primaries and colour matrix used in 709.

(UYVY will be an eternal confusion, since it usually is just used to
refer to the pixel packing order, it unfortunately has some meaning for
colourspace+friends too.)

NB, digital video is almost always 16-235 (even in R'G'B' land).
[ignoring chroma]


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