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

[James Almer]

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?
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.

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