On Tue, Jun 6, 2017 at 4:48 PM John P Poet <jpp...@gmail.com> wrote: > On Tue, Jun 6, 2017 at 4:40 PM Kieran Kunhya <kier...@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 >
From my SDI source, most frames have cc_count=20. Then there can be two or three frames without any CC packets, which are often followed by a single frame with with two or three VBI lines of CC packets: e.g. two or three groups of cc_count=20 in a single frame. When you asked if it is "bursting", I assume this is what you mean? If so, what would you suggest I do about it? Thanks, John _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
