[FFmpeg-devel] [PATCH] fftools/ffplay: fix rotation incorrect when frame contains the side_data(type is AV_FRAME_DATA_DISPLAYMATRIX)

[Zhao Zhili]

> -----Original Message-----
> From: ffmpeg-devel-bounces at ffmpeg.org <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of 1035567130 at qq.com
> Sent: 2022年8月31日 18:45
> To: ffmpeg-devel at ffmpeg.org
> Cc: Wang Yaqiang <wangyaqiang03 at kuaishou.com>; 1445440736 at qq.com
> Subject: [FFmpeg-devel] [PATCH] fftools/ffplay: fix rotation incorrect when frame contains the side_data(type is
> AV_FRAME_DATA_DISPLAYMATRIX)
> 
> From: Wang Yaqiang <wangyaqiang03 at kuaishou.com>
> 
> For example, if the jpeg contains exif information and the rotation direction is included in the exif,
> the displaymatrix will be set on the side_data of the frame when decoding.
> However, when ffplay is used to play the image, only the side data in the stream will be determined.
> It does not check whether the frame also contains rotation information, causing it to play in the wrong direction

When both per-stream and per-frame DISPLAYMATRIX exist, we need to decode how they work
together. Does one applied after the other, or one override the other? I have no idea.

Secondly, even If one is applied after the other, we shouldn't use two rotation filter
but merge the operation into a single one.

> ---
>  fftools/ffplay.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/fftools/ffplay.c b/fftools/ffplay.c
> index 9242047f5c..868123dc65 100644
> --- a/fftools/ffplay.c
> +++ b/fftools/ffplay.c
> @@ -1917,7 +1917,8 @@ static int configure_video_filters(AVFilterGraph *graph, VideoState *is, const c
>      if (autorotate) {
>          int32_t *displaymatrix = (int32_t *)av_stream_get_side_data(is->video_st, AV_PKT_DATA_DISPLAYMATRIX, NULL);
>          double theta = get_rotation(displaymatrix);
> -
> +        int frame_rotation_checked = 0;
> +    rotation:
>          if (fabs(theta - 90) < 1.0) {
>              INSERT_FILT("transpose", "clock");
>          } else if (fabs(theta - 180) < 1.0) {
> @@ -1930,6 +1931,15 @@ static int configure_video_filters(AVFilterGraph *graph, VideoState *is, const c
>              snprintf(rotate_buf, sizeof(rotate_buf), "%f*PI/180", theta);
>              INSERT_FILT("rotate", rotate_buf);
>          }
> +        if (!frame_rotation_checked) {
> +            frame_rotation_checked = 1;
> +            AVFrameSideData *sd = av_frame_get_side_data(frame,AV_FRAME_DATA_DISPLAYMATRIX);
> +            if (sd) {
> +                displaymatrix = (int32_t *)sd->data;
> +                theta = get_rotation(displaymatrix);
> +                goto rotation;
> +            }
> +        }
>      }
> 
>      if ((ret = configure_filtergraph(graph, vfilters, filt_src, last_filter)) < 0)
> --
> 2.33.0
> 
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