[FFmpeg-devel] [PATCH 3/7] avutil/frame: add a param change side data type

[James Almer]

On 1/22/2025 12:13 AM, Lynne wrote:
> 
> 
> On 22/01/2025 11:53, James Almer wrote:
>> Equivalent to the one from packet side data using 
>> AVSideDataParamChangeFlags,
>> and will be used for the same purpose with encoders.
>>
>> Signed-off-by: James Almer <jamrial at gmail.com>
>> ---
>>   libavutil/frame.c |  1 +
>>   libavutil/frame.h | 13 +++++++++++++
>>   2 files changed, 14 insertions(+)
>>
>> diff --git a/libavutil/frame.c b/libavutil/frame.c
>> index 10b59545f0..f3575afc31 100644
>> --- a/libavutil/frame.c
>> +++ b/libavutil/frame.c
>> @@ -48,6 +48,7 @@ static const AVSideDataDescriptor sd_props[] = {
>>       [AV_FRAME_DATA_DOVI_METADATA]               = { "Dolby Vision 
>> Metadata",                        AV_SIDE_DATA_PROP_COLOR_DEPENDENT },
>>       [AV_FRAME_DATA_LCEVC]                       = { "LCEVC NAL 
>> data",                               AV_SIDE_DATA_PROP_SIZE_DEPENDENT },
>>       [AV_FRAME_DATA_VIEW_ID]                     = { "View ID" },
>> +    [AV_FRAME_DATA_PARAM_CHANGE]                = { "Param Change" },
>>       [AV_FRAME_DATA_STEREO3D]                    = { "Stereo 
>> 3D",                                    AV_SIDE_DATA_PROP_GLOBAL },
>>       [AV_FRAME_DATA_REPLAYGAIN]                  = 
>> { "AVReplayGain",                                 
>> AV_SIDE_DATA_PROP_GLOBAL },
>>       [AV_FRAME_DATA_DISPLAYMATRIX]               = { "3x3 
>> displaymatrix",                            AV_SIDE_DATA_PROP_GLOBAL },
>> diff --git a/libavutil/frame.h b/libavutil/frame.h
>> index 628f2b5b3a..de7a8e9eab 100644
>> --- a/libavutil/frame.h
>> +++ b/libavutil/frame.h
>> @@ -243,6 +243,19 @@ enum AVFrameSideDataType {
>>        * The data is an int storing the view ID.
>>        */
>>       AV_FRAME_DATA_VIEW_ID,
>> +
>> +    /**
>> +     * An AV_FRAME_DATA_PARAM_CHANGE side data packet is laid out as 
>> follows:
>> +     * @code
>> +     * u32le param_flags
>> +     * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE)
>> +     *     s32le sample_rate
>> +     * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS)
>> +     *     s32le width
>> +     *     s32le height
>> +     * @endcode
>> +     */
>> +    AV_FRAME_DATA_PARAM_CHANGE,
> 
> Could you make the struct defined, and allocated by libavutil, like with 
> encode data and film grain?
> That way new fields could be added in the future.

New fields can be added this way too. The reason i didn't make it a 
struct is that i wanted to introduce the least amount of new public 
defines/symbols, thus reusing the packet side data implementation.

> 
> I'd also like for the FPS and timebase to be signaled. Encoders can 
> sometimes handle them gracefully, as its just a rate control parameter 
> change.
> 
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