[FFmpeg-devel] [PATCH v3 1/1] avformat/mpegtsenc: Write necessary descriptors into PMT for arib_caption muxing

zheng qian xqq at xqq.im
Wed Apr 21 09:49:21 EEST 2021


On Wed, Apr 21, 2021 at 10:00 AM zheng qian <xqq at xqq.im> wrote:
>
> ARIB superimpose should utilize Timing(00) since superimpose
> uses Asynchronous_PES, but it belongs to another topic.
>
> In other words, addtitional_arib_caption_info can be generated by
> profile information safely and is not necessary to copy by extradata.
>

P.S.: AFAIK the DMF and Timing field actually do not affect ARIB B24
subtitle decoder/renderers' behavior since they always follow the
TMD and DMF field in caption_management_data(), which is
periodically transmitted in arib_caption ES.

In TR-B24, the Timing field for Superimpose could be
'00'(Non-synchronization) or '01'(Time synchronization),
and AFAIK Superimpose used in Japan DTV has never utilized
Timing field rather than '00', since Superimpose is designed to
be displayed immediately once received and usually used for
providing urgent disaster alerts and newsletters (like NHK速報).

Later I'd like to introduce arib_superimpose codec for superimpose
recognition and remuxing, and I believe that for arib_superimpose,
using fixed value 00 for Timing doesn't cause problems in practice.

thus, I'm waiting for your opinion.

Regards,
zheng qian

> Regards,
> zheng
>
> > Feel free to note how you like these changes :)
> >
> > Jan
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