[FFmpeg-devel] [PATCH 07/10] lavf: document that AVStream::codecpar may be modified by lavf after avformat_write_header(). This is assumed not to break API because it's already true (see e.g. matroskaenc handling of new AAC extradata)

[Michael Niedermayer]

On Wed, Mar 14, 2018 at 01:24:42AM -0500, Rodger Combs wrote:
> ---
>  libavformat/avformat.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> index 9e87d6cdac..5f0ebfc114 100644
> --- a/libavformat/avformat.h
> +++ b/libavformat/avformat.h
> @@ -1006,7 +1006,8 @@ typedef struct AVStream {
>       *
>       * - demuxing: filled by libavformat on stream creation or in
>       *             avformat_find_stream_info()
> -     * - muxing: filled by the caller before avformat_write_header()
> +     * - muxing: filled by the caller before avformat_write_header();
> +     * -         may be modified by libavformat afterwards
>       */

a generic "anything can change" is not really practical
a user app would have to check every field of codecpar and possibly insert
video scalers if resoluton changed, or all kinds of other filters and even
different encoders if codec_id was adjusted ...

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

During times of universal deceit, telling the truth becomes a
revolutionary act. -- George Orwell
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