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

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

[Marth64]

---
 doc/bitstream_filters.texi | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
index 145aa8684e..b01ede0c93 100644
--- a/doc/bitstream_filters.texi
+++ b/doc/bitstream_filters.texi
@@ -213,6 +213,23 @@ 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
 
+By nature of removing SEI messages, the filter can also remove Closed Captions.
+
+To remove SEI messages (including CC) from a MPEG-2 stream:
+@example
+ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=178' OUTPUT
+@end example
+
+To remove SEI messages (including CC) from a H264 stream:
+@example
+ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=6' OUTPUT
+@end example
+
+To remove SEI messages (including CC and dynamic HDR) from a HEVC stream:
+@example
+ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=39' OUTPUT
+@end example
+
 @section hapqa_extract
 
 Extract Rgb or Alpha part of an HAPQA file, without recompression, in order to create an HAPQ or an HAPAlphaOnly file.
-- 
2.34.1

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

[Stefano Sabatini]

On date Saturday 2023-12-09 13:31:13 -0600, Marth64 wrote:
> ---
>  doc/bitstream_filters.texi | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
> index 145aa8684e..b01ede0c93 100644
> --- a/doc/bitstream_filters.texi
> +++ b/doc/bitstream_filters.texi
> @@ -213,6 +213,23 @@ 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
>  

> +By nature of removing SEI messages, the filter can also remove Closed Captions.

I think you might expand this to shortly explain the relation between
Closed Captions and SEI message. Also, I'd avoid the expression "by
nature" and replace with a plainer/more explicit expression (as most
of the readers are not English speakers).

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

[Marth64]

Appreciate the good feedback, will update. Thank you.

On Sat, Dec 9, 2023 at 6:53 PM Stefano Sabatini <stefasab@gmail.com> wrote:

> On date Saturday 2023-12-09 13:31:13 -0600, Marth64 wrote:
> > ---
> >  doc/bitstream_filters.texi | 17 +++++++++++++++++
> >  1 file changed, 17 insertions(+)
> >
> > diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
> > index 145aa8684e..b01ede0c93 100644
> > --- a/doc/bitstream_filters.texi
> > +++ b/doc/bitstream_filters.texi
> > @@ -213,6 +213,23 @@ 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
> >
>
> > +By nature of removing SEI messages, the filter can also remove Closed
> Captions.
>
> I think you might expand this to shortly explain the relation between
> Closed Captions and SEI message. Also, I'd avoid the expression "by
> nature" and replace with a plainer/more explicit expression (as most
> of the readers are not English speakers).
>
> [...]
>
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[FFmpeg-devel] [PATCH] doc/bitstream_filters: add filter_units practical examples for removing closed captions

[Marth64]

---
 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:
+@example
+ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=178' OUTPUT
+@end example
+
+To remove SEI messages (including CC) from a H264 stream:
+@example
+ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=6' OUTPUT
+@end example
+
+To remove SEI messages (including CC and dynamic HDR) from a HEVC stream:
+@example
+ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=39' OUTPUT
+@end example
+
 @section hapqa_extract
 
 Extract Rgb or Alpha part of an HAPQA file, without recompression, in order to create an HAPQ or an HAPAlphaOnly file.
-- 
2.34.1

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

[Leo Izen]

On 12/9/23 20:35, Marth64 wrote:
> ---
>   doc/bitstream_filters.texi | 18 ++++++++++++++++++
>   1 file changed, 18 insertions(+)
> 

Make sure when you generate the second version of a patch with git 
format-patch you pass the -v2 argument, e.g.

git format-patch -v2 -o outgoing/ master

Otherwise it can get a little bit difficult for reviewers to track the 
versions. I have no comments on the patch itself, in either direction.

- Leo Izen (Traneptora)
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Re: [FFmpeg-devel] [PATCH] doc/bitstream_filters: add filter_units practical examples for removing closed captions

[Marth64]

Thank you!

On Sat, Dec 9, 2023 at 9:06 PM Leo Izen <leo.izen@gmail.com> wrote:

> On 12/9/23 20:35, Marth64 wrote:
> > ---
> >   doc/bitstream_filters.texi | 18 ++++++++++++++++++
> >   1 file changed, 18 insertions(+)
> >
>
> Make sure when you generate the second version of a patch with git
> format-patch you pass the -v2 argument, e.g.
>
> git format-patch -v2 -o outgoing/ master
>
> Otherwise it can get a little bit difficult for reviewers to track the
> versions. I have no comments on the patch itself, in either direction.
>
> - Leo Izen (Traneptora)
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
>
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Re: [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:
> +@example
> +ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=178' OUTPUT
> +@end example
> +
> +To remove SEI messages (including CC) from a H264 stream:
> +@example
> +ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=6' OUTPUT
> +@end example
> +
> +To remove SEI messages (including CC and dynamic HDR) from a HEVC stream:
> +@example
> +ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=39' OUTPUT
> +@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:
...
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[FFmpeg-devel] [PATCH v2] doc/bitstream_filters: add filter_units practical examples for removing closed captions

[Marth64]

Added v2 label and signed off as per proper procedure.

Signed-off-by: Marth64 <marth64@proxyid.net>
---
 doc/bitstream_filters.texi | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
index dc4f85bac0..7c36c5346d 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:
+@example
+ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=178' OUTPUT
+@end example
+
+To remove SEI messages (including CC) from a H264 stream:
+@example
+ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=6' OUTPUT
+@end example
+
+To remove SEI messages (including CC and dynamic HDR) from a HEVC stream:
+@example
+ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=39' OUTPUT
+@end example
+
 @section hapqa_extract
 
 Extract Rgb or Alpha part of an HAPQA file, without recompression, in order to create an HAPQ or an HAPAlphaOnly file.
-- 
2.34.1

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Re: [FFmpeg-devel] [PATCH v2] doc/bitstream_filters: add filter_units practical examples for removing closed captions

[Mark Thompson]

On 11/12/2023 16:33, Marth64 wrote:
> Added v2 label and signed off as per proper procedure.
> 
> Signed-off-by: Marth64 <marth64@proxyid.net>
> ---
>   doc/bitstream_filters.texi | 18 ++++++++++++++++++
>   1 file changed, 18 insertions(+)
> 
> diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
> index dc4f85bac0..7c36c5346d 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:
> +@example
> +ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=178' OUTPUT
> +@end example

MPEG-2 doesn't call these SEI, it is simply "user data".

> +
> +To remove SEI messages (including CC) from a H264 stream:
> +@example
> +ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=6' OUTPUT
> +@end example
> +
> +To remove SEI messages (including CC and dynamic HDR) from a HEVC stream:
> +@example
> +ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=39' OUTPUT
> +@end example

Are closed captions allowed in suffix SEI as well?  T.35 messages are certainly allowed there.

(I'm mildly inclined to think that a more specific bitstream filter able to mess with the SEI types would be more useful?  This approach feels like it has a lot of collateral damage.)

Thanks,

- Mark
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