[FFmpeg-devel] [PATCH] Add A53 Closed Captions to MPEG header if they are available.
John P Poet
jppoet at gmail.com
Wed Jun 7 01:48:02 EEST 2017
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
> > 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
> > 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?
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.
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