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

[lance.lmwang at gmail.com]

On Wed, Mar 18, 2020 at 10:42:12AM +0000, Kieran Kunhya wrote:
> 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?
I just give one use case for the unregistered user data. Actual We have more other private info
in the json string. timecode SEI is helpful, but it's not enough..

> You do know that the time at source will not match the rate at which frames
> arrive, there will be a drift?

Yes, we inserted the live time in the second level device, it's not require to be frame accurate.

> 
> Kieran
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-- 
Thanks,
Limin Wang