[FFmpeg-devel] Default color range encoding in Avid ACLR tags embeedded in QuickTime .movs

[Kevin Wheatley]

On Tue, Feb 10, 2015 at 10:34 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
> if theres no way to store unknown range then your suggestion sounds
> reasonable, can you send a patch?

I'm not aware of a value to specify in the ACLR atom for unspecified -
I could guess at a value of 0 but that is pure speculation, Avid
directly (or via the official QuickTime codecs) only ever uses the
values of 1 or 2 from what I can see.

Patch yes I can do that, should this be a simple if statement modification e.g.

    if (track->enc->color_range == AVCOL_RANGE_MPEG || /* Legal range
(16-235) */
        track->enc->color_range == AVCOL_RANGE_UNSPECIFIED) {
        avio_wb32(pb, 1); /* Corresponds to 709 in official encoder */
    } else { /* Full range (0-255) */
        avio_wb32(pb, 2); /* Corresponds to RGB in official encoder */
    }

or does ffmpeg favor a switch/multiple if to handle each of the cases?

> is there some advantage in doing that default handling specific to
> the codec_id ?

I'm not sure what you mean, in this case the atom being written is
specific to certain codecs (although currently ffmpeg only does this
for DNxHD)

Thanks

Kevin