[FFmpeg-devel] [PATCH 1/4] lavu/frame: allow calling av_frame_make_writable() on non-refcounted frames

[James Almer]

On 7/17/2022 4:26 PM, Anton Khirnov wrote:
> This is an easy way to make a refcounted frame from a non-refcounted
> one.
> ---
>   doc/APIchanges      | 5 +++++
>   libavutil/frame.c   | 3 ---
>   libavutil/frame.h   | 3 ++-
>   libavutil/version.h | 2 +-
>   4 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/doc/APIchanges b/doc/APIchanges
> index f9a1484bbc..4e218af94e 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -14,6 +14,11 @@ libavutil:     2021-04-27
>   
>   API changes, most recent first:
>   
> +2022-07-xx - xxxxxxxxxx - lavu 57.30.100 - frame.h
> +  av_frame_make_writable() may now be called on non-refcounted
> +  frames and will make a refcounted copy out of them.
> +  Previously an error was returned in such cases.
> +
>   -------- 8< --------- FFmpeg 5.1 was cut here -------- 8< ---------
>   
>   2022-06-12 - 7cae3d8b76 - lavf 59.25.100 - avio.h
> diff --git a/libavutil/frame.c b/libavutil/frame.c
> index 4c16488c66..7408817e1f 100644
> --- a/libavutil/frame.c
> +++ b/libavutil/frame.c
> @@ -542,9 +542,6 @@ int av_frame_make_writable(AVFrame *frame)
>       AVFrame tmp;
>       int ret;
>   
> -    if (!frame->buf[0])
> -        return AVERROR(EINVAL);
> -
>       if (av_frame_is_writable(frame))
>           return 0;
>   
> diff --git a/libavutil/frame.h b/libavutil/frame.h
> index 33fac2054c..cc55d67e3c 100644
> --- a/libavutil/frame.h
> +++ b/libavutil/frame.h
> @@ -818,7 +818,8 @@ int av_frame_is_writable(AVFrame *frame);
>    * Ensure that the frame data is writable, avoiding data copy if possible.
>    *
>    * Do nothing if the frame is writable, allocate new buffers and copy the data
> - * if it is not.
> + * if it is not. Non-refcounted frames behave as non-writable, i.e. a copy
> + * is always made.
>    *
>    * @return 0 on success, a negative AVERROR on error.
>    *
> diff --git a/libavutil/version.h b/libavutil/version.h
> index f185322550..734d3f8330 100644
> --- a/libavutil/version.h
> +++ b/libavutil/version.h
> @@ -79,7 +79,7 @@
>    */
>   
>   #define LIBAVUTIL_VERSION_MAJOR  57
> -#define LIBAVUTIL_VERSION_MINOR  29
> +#define LIBAVUTIL_VERSION_MINOR  30
>   #define LIBAVUTIL_VERSION_MICRO 100
>   
>   #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \

LGTM.