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

[Kieran Kunhya]

On Wed, 18 Mar 2020 at 02:38, Limin Wang <lance.lmwang at gmail.com> 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
>

And the timecode field is not enough?
You do know that the time at source will not match the rate at which frames
arrive, there will be a drift?

Kieran