Re: [FFmpeg-devel] [PATCH] avformat/demux: Add allow_codec_changes option to AVFormatContext (v2)

[Michael Niedermayer <michael@niedermayer.cc>]

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On Tue, Jun 17, 2025 at 08:36:59AM -0600, Pavel Koshevoy 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/APIchanges              |  3 +++
>  doc/formats.texi            |  6 ++++++
>  libavformat/avformat.h      | 10 ++++++++++
>  libavformat/demux.c         |  8 +++++++-
>  libavformat/mpegts.c        |  4 +++-
>  libavformat/options_table.h |  1 +
>  libavformat/version.h       |  2 +-
>  tests/fate/demux.mak        |  2 +-
>  8 files changed, 32 insertions(+), 4 deletions(-)

[...]

> diff --git a/libavformat/demux.c b/libavformat/demux.c
> index ecd4f40da9..3749ab67a3 100644
> --- a/libavformat/demux.c
> +++ b/libavformat/demux.c
> @@ -1292,9 +1292,15 @@ static int codec_close(FFStream *sti)
>  {
>      AVCodecContext *avctx_new = NULL;
>      AVCodecParameters *par_tmp = NULL;
> +    const AVCodec *new_codec = NULL;
>      int ret;
>  
> -    avctx_new = avcodec_alloc_context3(sti->avctx->codec);
> +    new_codec =
> +      (sti->avctx->codec_id != sti->pub.codecpar->codec_id) ?
> +      avcodec_find_decoder(sti->pub.codecpar->codec_id) :
> +      sti->avctx->codec;
> +
> +    avctx_new = avcodec_alloc_context3(new_codec);
>      if (!avctx_new) {
>          ret = AVERROR(ENOMEM);
>          goto fail;

this should be a seperate patch


thx

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

Republics decline into democracies and democracies degenerate into
despotisms. -- Aristotle

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