[FFmpeg-devel] [PATCH] Add A53 Closed Captions to MPEG header if they are available.

[John P Poet]

On Tue, Jun 6, 2017 at 4:40 PM Kieran Kunhya <kierank at obe.tv> wrote:

> >
> > The cc_count is only 5 bits, which mean that only 31 3-byte "closed
> caption
> > constructs" will fit in a "block".    Testing this with 1080i60
> material, I
> > found that 2 or 3 blocks was often necessary to hold all of the CC data.
> >
> > I tried ignoring that limit of 31 "constructs" per block, and ended up
> with
> > corrupt captions.   By preserving the 2 or 3 separate blocks I observed
> > from the original source, the captions are perfect.
> >
>
> Odd, ATSC specifies specific bitrate requirements in this area. Are you
> sure your insertion process isn't  bursting?
>
> Kieran
>

The source is SDI with embedded 708 captions.  I supposed there may be an
issue there.  I have not tried this with any other source.

John