[FFmpeg-devel] [PATCH 1/4] avformat/avformat: add a new disposition to signal the stream is an HDR gainmap

[Anton Khirnov]

Quoting James Almer (2024-09-26 14:06:25)
> On 9/26/2024 3:00 AM, Anton Khirnov wrote:
> > Quoting James Almer (2024-09-26 00:52:16)
> >> HDR images photos taken by certain cameras split this as a separate image.
> >>
> >> Signed-off-by: James Almer <jamrial at gmail.com>
> >> ---
> >>   libavformat/avformat.h | 5 +++++
> >>   libavformat/dump.c     | 2 ++
> >>   2 files changed, 7 insertions(+)
> >>
> >> diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> >> index 56c1c80289..6d9f5c4399 100644
> >> --- a/libavformat/avformat.h
> >> +++ b/libavformat/avformat.h
> >> @@ -718,6 +718,11 @@ typedef struct AVIndexEntry {
> >>    * Annex G/H, or HEVC Annex F).
> >>    */
> >>   #define AV_DISPOSITION_MULTILAYER           (1 << 21)
> >> +/**
> >> + * The video stream contains an HDR gainmap. Only ever used with
> >> + * AV_DISPOSITION_DEPENDENT.
> >> + */
> >> +#define AV_DISPOSITION_GAINMAP              (1 << 22)
> > 
> > Presumably we want this information available in codecs and filters as
> > well, so then should it not be side data instead?
> 
> There is no other information than "This is a gainmap", and that's 
> container level information (Same as "This is a tile" for heif). How 
> would side data work for this?

You could e.g. have side data that has no payload, and its presence
signals the same information.

> I'm including it in the tile grid stream group in patch 4/4, so that 
> should give the caller all the information they need.

Assuming all they ever need is handle everything manually.

-- 
Anton Khirnov