[FFmpeg-devel] [PATCH] doc/bitstream_filters: add filter_units practical examples for removing closed captions

[Stefano Sabatini]

On date Saturday 2023-12-09 19:35:50 -0600, Marth64 wrote:
> ---
>  doc/bitstream_filters.texi | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
> index c63c20370f..d2ad6e78ff 100644
> --- a/doc/bitstream_filters.texi
> +++ b/doc/bitstream_filters.texi
> @@ -213,6 +213,24 @@ To remove all AUDs, SEI and filler from an H.265 stream:
>  ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=35|38-40' OUTPUT
>  @end example
>  
> +SEI messages are commonly used to contain Closed Captions as well as other metadata such as dynamic HDR.
> +This filter can be used to remove the SEI messages if desired.
> +
> +To remove SEI messages (including CC) from a MPEG-2 stream:
> + at example
> +ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=178' OUTPUT
> + at end example
> +
> +To remove SEI messages (including CC) from a H264 stream:
> + at example
> +ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=6' OUTPUT
> + at end example
> +
> +To remove SEI messages (including CC and dynamic HDR) from a HEVC stream:
> + at example
> +ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=39' OUTPUT
> + at end example

Shall be good, but probably we can still do a bit better, by making
explicit the common pattern.

Something as:
...

SEI messages are commonly used to contain Closed Captions as well as
other metadata such as dynamic HDR.

This filter can be used to remove the SEI messages, including CC,
given the bitstream SEI unit type (which changes depending on the
video stream).

To remove SEI messages (including CC) from a MPEG-2 stream:
...