[FFmpeg-devel] Stream with Closed caption does not set appropriate flag

anshul anshul.ffmpeg at gmail.com
Mon Mar 10 12:12:53 CET 2014


On 03/10/2014 02:28 PM, Nicolas George wrote:
> (I believe I do not have the privileges to do it, but I suggest someone adds
> it to the sample collection with a clear file name to show it contains
> CEA-708 subcc.
Its CEA-608 not 708
> Thanks for that too, of course. Per any chance, do you also have code 
> that turns the contents of that file into useful information: timing 
> and text?
here is link 
<ourceforge.net/projects/ccextractor/files/ccextractor/0.68/ccextractor.src.0.68.zip/download> 
of ccextractor
The source code is very big and does not use ffmpeg at all.

For timing we can look at packet pts if you want it to do with ffmpeg.


I am interested in adding this feature myself for ffmpeg ,I would 
appreciate if you give direction rather then solving.

This issue has been disscussed already in #1778, for quick reference 
adding those comments


      Changed 17 months ago
      <http://trac.ffmpeg.org/timeline?from=2012-10-02T19%3A33%3A53Z&precision=second>
      by reimar

The situation is not quite as simple.
The problem in this specific case is that it does not have CC data in a 
separate stream but embedded in the video frame data.
FFmpeg currently has no way of handling this mess where one stream 
(video) contains another one (subtitles/CC).
CC in e.g. wtv, mxf and even mov as in ticket #846 
<http://trac.ffmpeg.org/ticket/846> is actually supported in so far as 
extracting it is possible, we just can't decode it into plain text or 
such and we can't mux it either.


      Changed 17 months ago
      <http://trac.ffmpeg.org/timeline?from=2012-10-02T20%3A05%3A54Z&precision=second>
      by mikecheat04

I see. Could any of the code from the libzvbi project maybe help with 
this? It seems they've found a way to gather that information from the 
video stream and then mux it into a TS. There is also another project 
called OB-Encoder, they use libav, libx264, and libzvbi with a third 
party mpegts muxer to produce the desired output. I could use their 
program but they don't currently support mpeg2 and some of the more 
advance features of ffmepg that I've accustomed to.

libzvbi - http://zapping.sourceforge.net/ZVBI/Download.html
obencoder - http://code.google.com/p/open-broadcast-encoder/downloads/list


Thanks
Anshul


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