[FFmpeg-devel] [PATCH] doc/examples/muxing: Fix av_frame_make_writable usage

[wm4]

On Mon, 24 Oct 2016 00:12:00 +0200
Sam Hocevar <sam at hocevar.net> wrote:

> This patch moves the av_frame_make_writable() call from fill_yuv_image
> to get_video_frame so that its argument can be the actual frame that
> will be sent to the encoder.
> 
> This fixes data corruption issues in codecs that keep references on
> one or several previous frames.
> 
> Signed-off-by: Sam Hocevar <sam at hocevar.net>
> ---
>  doc/examples/muxing.c | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/doc/examples/muxing.c b/doc/examples/muxing.c
> index f1f5bb8..1df5912 100644
> --- a/doc/examples/muxing.c
> +++ b/doc/examples/muxing.c
> @@ -440,15 +440,7 @@ static void open_video(AVFormatContext *oc, AVCodec *codec, OutputStream *ost, A
>  static void fill_yuv_image(AVFrame *pict, int frame_index,
>                             int width, int height)
>  {
> -    int x, y, i, ret;
> -
> -    /* when we pass a frame to the encoder, it may keep a reference to it
> -     * internally;
> -     * make sure we do not overwrite it here
> -     */
> -    ret = av_frame_make_writable(pict);
> -    if (ret < 0)
> -        exit(1);
> +    int x, y, i;
>  
>      i = frame_index;
>  
> @@ -475,6 +467,11 @@ static AVFrame *get_video_frame(OutputStream *ost)
>                        STREAM_DURATION, (AVRational){ 1, 1 }) >= 0)
>          return NULL;
>  
> +    /* when we pass a frame to the encoder, it may keep a reference to it
> +     * internally; make sure we do not overwrite it here */
> +    if (av_frame_make_writable(ost->frame) < 0)
> +        exit(1);
> +
>      if (c->pix_fmt != AV_PIX_FMT_YUV420P) {
>          /* as we only generate a YUV420P picture, we must convert it
>           * to the codec pixel format if needed */

LGTM, but I'm not in a position to push now.