[FFmpeg-devel] [PATCH v2 6/7] avformat/matroskaenc: support writing Dynamic HDR10+ packet side data

[James Almer]

On 3/24/2023 8:58 AM, Anton Khirnov wrote:
> Quoting James Almer (2023-03-24 12:50:40)
>> On 3/24/2023 8:45 AM, Anton Khirnov wrote:
>>> Quoting James Almer (2023-03-21 19:00:01)
>>>> @@ -3095,6 +3153,12 @@ after_cues:
>>>>                avio_seek(mkv->track.bc, track->blockadditionmapping_offset, SEEK_SET);
>>>>    
>>>>                put_ebml_uint(mkv->track.bc, MATROSKA_ID_TRACKMAXBLKADDID, track->max_blockaddid);
>>>> +            if (track->max_blockaddid == 4) { // HDR10+
>>>
>>> Maybe this magic 4 deserves a name too?
>>
>> Is has no name. See
>> https://www.matroska.org/technical/codec_specs.html#itu-t35-metadata
>>
>> It only defines a name for the BlockAddIDType, which i used, and
>> constricts the BlockAddIDValue to be used for it to 4.
>> It's not necessarily HDR10+ (i can remove that comment if it makes it
>> look like it should be named), it's potentially any ITU-T T35 payload of
>> which we only care about HDR10+, so i can't name it that. It's simply 4.
> 
> MATROSKA_BLOCKADDITIONAL_ITUT35_VAL then?

4 as BlockAddID is valid for any mapped BlockAddIDType value, not just 
MATROSKA_BLOCK_ADD_ID_TYPE_ITU_T_T35.
But ok, i'll add a #define for it. If we ever start writing other types, 
like SMPTE ST 12-1 Timecode, we could just make sure to never use 4 for it.