[FFmpeg-devel] [PATCH v4 1/3] avformat: add fields to AVProgram/AVStream for PMT change tracking

[Michael Niedermayer]

On Fri, May 18, 2018 at 11:15:04AM -0700, Aman Gupta wrote:
> From: Aman Gupta <aman at tmm1.net>
> 
> These fields will allow the mpegts demuxer to expose details about
> the PMT/program which created the AVProgram and its AVStreams.
> 
> In mpegts, a PMT which advertises streams has a version number
> which can be incremented at any time. When the version changes,
> the pids which correspond to each of it's streams can also change.
> 
> Since ffmpeg creates a new AVStream per pid by default, an API user
> needs the ability to (a) detect when the PMT changed, and (b) tell
> which AVStream were added to replace earlier streams.
> 
> This has been a long-standing issue with ffmpeg's handling of mpegts
> streams with PMT changes, and I found two related patches in the wild
> that attempt to solve the same problem.
> 
> The first is in MythTV's ffmpeg fork, where they added a
> void (*streams_changed)(void*); to AVFormatContext and call it from
> their fork of the mpegts demuxer whenever the PMT changes.
> 
> The second was proposed by XBMC in
> https://ffmpeg.org/pipermail/ffmpeg-devel/2012-December/135036.html,
> where they created a new AVMEDIA_TYPE_DATA stream with id=0 and
> attempted to send packets to it whenever the PMT changed.
> 
> Signed-off-by: Aman Gupta <aman at tmm1.net>
> ---
>  doc/APIchanges         | 4 ++++
>  libavformat/avformat.h | 8 ++++++++
>  libavformat/utils.c    | 1 +
>  libavformat/version.h  | 2 +-
>  4 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/doc/APIchanges b/doc/APIchanges
> index befa58c84a..a592073ca5 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -15,6 +15,10 @@ libavutil:     2017-10-21
>  
>  API changes, most recent first:
>  
> +2018-05-xx - xxxxxxxxxx - lavf 58.15.100 - avformat.h
> +  Add pmt_version field to AVProgram
> +  Add program_num, pmt_version, pmt_stream_idx to AVStream
> +
>  2018-05-xx - xxxxxxxxxx - lavf 58.14.100 - avformat.h
>    Add AV_DISPOSITION_STILL_IMAGE
>  
> diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> index 6dce88fad5..ade918f99c 100644
> --- a/libavformat/avformat.h
> +++ b/libavformat/avformat.h
> @@ -1103,6 +1103,13 @@ typedef struct AVStream {
>       */
>      int stream_identifier;
>  
> +    /**
> +     * Details of the MPEG-TS program which created this stream.
> +     */
> +    int program_num;
> +    int pmt_version;
> +    int pmt_stream_idx;
> +
>      int64_t interleaver_chunk_size;
>      int64_t interleaver_chunk_duration;
>  

These are added below the "All fields below this line are not part of the public API."
This contradicts the addition to APIChanges

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If you think the mosad wants you dead since a long time then you are either
wrong or dead since a long time.
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