[FFmpeg-devel] [PATCH v9 2/4] avcodec/hevc_sei: add support for user data unregistered SEI message

[James Almer]

On 3/17/2020 11:37 PM, Limin Wang wrote:
> On Wed, Mar 18, 2020 at 12:13:33AM +0000, Derek Buitenhuis wrote:
>> On 17/03/2020 23:11, Limin Wang wrote:
>>> The user data unregistered allows arbitrary data to be carried in the bitstream,
>>> for example, ROI info, time info etc. For the real support patch, please refer to
>>> the pending patch series 7, 8 in below link:
>>> https://patchwork.ffmpeg.org/project/ffmpeg/patch/20200107050355.17503-1-lance.lmwang@gmail.com/
>>
>> I understand what the SEI does. I was inquiring as to what the usecase you had
>> in mind for it specifically. I don't like the idea of adding APIs that are only
>> theorically useful - that is, what data is intended to be shoved in there?
> 
> In order to identify the source of time used in the live event, the encoder system can
> insert a time mode-source code along with each embedded precision time stamp. 
> Each time mode-source code will be inserted into the H.264/H.265 bitstream as an SEI
> message of type User Data (Unregistered). The format is self-defined json string 

You may want to look at the Producer Reference Time side data, then.