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

Kieran Kunhya kierank at obe.tv
Wed Jun 7 01:40:20 EEST 2017

> 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?


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