[FFmpeg-devel] [PATCH 8/8] avcodec/avcodec: Document current behaviour for extradata

[James Almer]

On 4/24/2021 9:29 AM, Andreas Rheinhardt wrote:
> Despite the documentation saying that it is not freed by libavcodec
> for a decoder, avcodec_free_context() does so and has been doing so
> since this function has been added more than seven years ago.
> 
> Honouring the current documentation in avcodec_free_context() would
> add memleaks to all users of it that don't free their extradata
> manually; given how long this behaviour has been around we can safely
> assume that these are many (i.e. the fftools are among them, as is
> libavformat as well as parts of libavcodec itself).
> 
> Therefore adapt the documentation to match actual behaviour.
> This fixes ticket #5027.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> ---
>   libavcodec/avcodec.h | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> index b9b487be41..4596d12647 100644
> --- a/libavcodec/avcodec.h
> +++ b/libavcodec/avcodec.h
> @@ -633,6 +633,8 @@ typedef struct AVCodecContext {
>        * Must be allocated with the av_malloc() family of functions.
>        * - encoding: Set/allocated/freed by libavcodec.
>        * - decoding: Set/allocated/freed by user.
> +     * Additionally, avcodec_free_context() frees it regardless of whether
> +     * the context is used for encoding or not.

I'd prefer to instead change the decoding line to

* - decoding: Set/allocated by user, freed by libavcodec.