[FFmpeg-user] Setting colour range.

[Kieran O Leary]

On Tue, 27 Nov 2018, 15:56 Gyan Doshi <gyandoshi at gmail.com wrote:

> On 27-11-2018 09:17 PM, Gyan Doshi wrote:
> > On 27-11-2018 08:59 PM, Kieran O Leary wrote:
> >
> >>
> >> Can this metadata ever be set at a container level for mov? Must it
> >> always
> >> be the stream that holds this info?
> >
> > The muxer only writes it for MP4s,
> >
> > The QT spec doesn't accommodate its signaling :
> >
>
> >
> https://developer.apple.com/library/archive/technotes/tn2162/_index.html#//apple_ref/doc/uid/DTS40013070-CH1-TNTAG7
>
> Correction. Meant to quote this,
>
>      "The remaining component values (e.g., 1-15 and 241-254 for n=8
> bits and 4-63 and 961-1019 for n=10 bits) accommodate occasional filter
> undershoot and overshoot in image processing. In some applications,
> these values are used to carry other information (e.g., transparency).
> The writer of a QuickTime image may use these values and the reader of a
> QuickTime image must expect these values."
>
> This implies that 'these values' is treated as 'other information'
> rather than range expansion.
>

This is wonderful. No wonder I could find no information in the atom
description regarding these values! I thought that the colr atom would be
where it was stored.

Thanks Gyan,

Kieran O'Leary
Irish Film Institute