Re: [FFmpeg-devel] [PATCH] avformat/demux: Add allow_codec_changes option to AVFormatContext

[Pavel Koshevoy <pkoshevoy-at-gmail.com@ffmpeg.org>]

On Tue, Jun 17, 2025 at 8:00 AM Pavel Koshevoy <pkoshevoy@gmail.com> wrote:

>
>
> On Tue, Jun 17, 2025, 07:55 Pavel Koshevoy <pkoshevoy@gmail.com> wrote:
>
>> Ping.  I think I've addressed the concerns raised with the previous
>> patch.
>> Please let me know if I may commit this... it is a segfault fix, so it
>> probably should get some review priority.
>>
>> Thank you,
>>     Pavel
>>
>>
>> On Sun, Jun 15, 2025, 14:50 Pavel Koshevoy <pkoshevoy@gmail.com> wrote:
>>
>>> Make runtime AVStream.codecpar codec_id updates optional and disabled
>>> by default, so that avformat API clients can enable this feature
>>> explicitly
>>> when they add support for runtime codec changes.
>>>
>>> Accordingly, codec_close should not assume that the codec_id cannot
>>> change.
>>> This fixes 'ffprobe 1_poc.mp4' segfault introduced with
>>> commit 0021484d05f9b0f032fa319399de6e24eea0c04f
>>> ---
>>>  doc/formats.texi            |  6 ++++++
>>>  libavformat/avformat.h      | 10 ++++++++++
>>>  libavformat/demux.c         |  8 +++++++-
>>>  libavformat/mpegts.c        |  4 +++-
>>>  libavformat/options_table.h |  1 +
>>>  tests/fate/demux.mak        |  2 +-
>>>  6 files changed, 28 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/doc/formats.texi b/doc/formats.texi
>>> index 876a9e92b3..d18613f8bd 100644
>>> --- a/doc/formats.texi
>>> +++ b/doc/formats.texi
>>> @@ -228,6 +228,12 @@ would require too many resources due to a large
>>> number of streams.
>>>  Skip estimation of input duration if it requires an additional probing
>>> for PTS at end of file.
>>>  At present, applicable for MPEG-PS and MPEG-TS.
>>>
>>> +@item allow_codec_changes @var{bool} (@emph{input})
>>> +Allow AVStream.codecpar codec_type and codec_id to change at runtime
>>> +(for example when MPEG-TS PMT ES stream_type changes at runtime).
>>> +This is disabled by default, because most clients of avformat API
>>> +do not support random mid-stream codec changes.
>>> +
>>>  @item duration_probesize @var{integer} (@emph{input})
>>>  Set probing size, in bytes, for input duration estimation when it
>>> actually requires
>>>  an additional probing for PTS at end of file (at present: MPEG-PS and
>>> MPEG-TS).
>>> diff --git a/libavformat/avformat.h b/libavformat/avformat.h
>>> index b6c63e2237..c6956626b5 100644
>>> --- a/libavformat/avformat.h
>>> +++ b/libavformat/avformat.h
>>> @@ -1884,6 +1884,16 @@ typedef struct AVFormatContext {
>>>       * @see skip_estimate_duration_from_pts
>>>       */
>>>      int64_t duration_probesize;
>>> +
>>> +    /**
>>> +     * Allow AVStream.codecpar codec_type and codec_id to change at
>>> runtime
>>> +     * (for example when MPEG-TS PMT ES stream_type changes at runtime).
>>> +     * This is disabled by default, because most clients of avformat API
>>> +     * do not support random mid-stream codec changes.
>>> +     * - muxing: unused
>>> +     * - demuxing: set by user
>>> +     */
>>> +    int allow_codec_changes;
>>>  } AVFormatContext;
>>>
>>
> Oops, I forgot to bump up the minor version.
>
>
I've sent a v2 of the patch, with LIBAVFORMAT_VERSION_MINOR bumped to 2 and
APIchanges note added.

Thank you,
    Pavel.
_______________________________________________
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".