[FFmpeg-user] How do I include ATSC closed captions in a file conversion?

[Anshul]

On December 10, 2014 1:43:08 AM IST, voip at gmx.ca wrote:
>I receive satellite TV signals and one channel sends its audio as three
>separate streams of two channels each, therefore the result is a .ts
>file where in most software I can select two channels but never get the
>full 5.1 channel sound.  I was directed to a web page that shows how to
>map these to a single ac3 stream, using a ffmpeg command of this
>format:
> 
>ffmpeg -loglevel quiet -i "original.ts" -c:v copy -filter_complex
>'[0:1][0:2][0:3]amerge=inputs=3,pan=5.1|FL=c0|FR=c1|FC=c2|LFE=c3|BL=c4|BR=c5'
>-c:a ac3 "converted.ts"
> 
>Note that the output file does need to stay in .ts format, for reasons
>that are not important to this question.
> 
>This works quite well except that in the original file, there is ATSC
>closed caption information.  If I run mediainfo on the source file it
>shows these text streams:
>
>Text #1
>ID                                       : 49 (0x31)-CC1
>Menu ID                                  : 1 (0x1)
>Format                                   : EIA-608
>Muxing mode                              : A/53 / DTVCC Transport
>Muxing mode, more info                   : Muxed in Video #1
>Duration                                 : 1h 2mn
>Bit rate mode                            : Constant
>Stream size                              : 0.00 Byte (0%)
>
>Text #2
>ID                                       : 49 (0x31)-CC3
>Menu ID                                  : 1 (0x1)
>Format                                   : EIA-608
>Muxing mode                              : A/53 / DTVCC Transport
>Muxing mode, more info                   : Muxed in Video #1
>Duration                                 : 1h 2mn
>Bit rate mode                            : Constant
>Stream size                              : 0.00 Byte (0%)
>
>Text #3
>ID                                       : 49 (0x31)-1
>Menu ID                                  : 1 (0x1)
>Format                                   : EIA-708
>Muxing mode                              : A/53 / DTVCC Transport
>Muxing mode, more info                   : Muxed in Video #1
>Duration                                 : 1h 2mn
>Bit rate mode                            : Constant
>Stream size                              : 0.00 Byte (0%)
>
>Text #4
>ID                                       : 49 (0x31)-2
>Menu ID                                  : 1 (0x1)
>Format                                   : EIA-708
>Muxing mode                              : A/53 / DTVCC Transport
>Muxing mode, more info                   : Muxed in Video #1
>Duration                                 : 1h 2mn
>Bit rate mode                            : Constant
>Stream size                              : 0.00 Byte (0%)
>
>If I run mediainfo on the output file, none of these appear.  What
>confuses me is that they all show "Muxing mode, more info : Muxed in
>Video #1" and as far as I can tell the above ffmpeg command only copies
>the video stream without changing it, so I don't understand why they
>aren't present in the output file.
>
>Is there any way I can make sure the closed captions remain in the
>output file?  They are very helpful to me on occasion, and would
>probably be much more so for anyone with significant hearing loss.
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This functionality is under development, if you have some urgent requirements then search for mail with subject adding closed caption, and please give ur feedback and if you are intrested can add more features in the development version of closed caption.


Mostly closed caption is embedded inside video, if you transcode video, you will probably loose the cosed caption content.

If you have closed caption in different stream, u should use -scodec copy.

-Anshul

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