[FFmpeg-devel] [PATCH 3/3] vf_colorspace: Allow overriding input color properties

[Vittorio Giovara]

On Fri, Aug 26, 2016 at 12:59 AM, Ronald S. Bultje <rsbultje at gmail.com> wrote:
> Hi Vittorio,
>
> On Thu, Aug 25, 2016 at 7:14 PM, Vittorio Giovara
> <vittorio.giovara at gmail.com> wrote:
>>
>> The filter needs input frames with color properties filled out by
>> the decoder. Since this is not always possible, add input options to
>> the filter so that user may override color space, color primaries,
>> transfer characteristics, and color range.
>>
>> Signed-off-by: Vittorio Giovara <vittorio.giovara at gmail.com>
>> ---
>> Please keep me in CC.
>> Vittorio
>
> [..]
>
> Do you think it makes sense to have a "iall" property, similar to "all"?
> iprm/irange/itr/iprimeries would take precedence over iall, but iall could
> be used to set all 4 at once in the (common) case where they are consistent.

Hi Ronald,
I had thought of that, but I am not sure.

In order to "guess" the input parameters one would need to rely on
either an external analyzer, which is going to report properties one
by one, or determine them via various heuristics: this latter case
might not be very precise, so one could decide to avoid performing
conversion altogether, or only perform it if some of the color
properties are already present (so that you'd only need to override
one or two).

Also I found that it's hard to identify a common consistent format:
for example, my files are often tagged with a mixture of bt470bg,
bt470m or smpte formats, and none follow a sensible pattern (with the
exception of bt709). So overall I'd say this `iall` option is not
really need, but if open to other opinions too.
-- 
Vittorio