Re: [FFmpeg-devel] [PATCH] fftools/ffplay.c: fix rotate error when displaymatrix contains flip

[Leo Izen <leo.izen@gmail.com>]

On 3/9/23 04:49, 1035567130@qq.com wrote:
> From: Wang Yaqiang <wangyaqiang03@kuaishou.com>
> 
> The angle is calculated by the get_rotation function,
> but it needs to be combined with the displaymatrix to determine whether flip or rotate,
> which is consistent with the processing logic in ffmpeg_filter.c
> 
> Signed-off-by: Wang Yaqiang <wangyaqiang03@kuaishou.com>
> ---
>   fftools/ffplay.c | 16 ++++++++++++----
>   1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/fftools/ffplay.c b/fftools/ffplay.c
> index d6479aef5f..860bac367a 100644
> --- a/fftools/ffplay.c
> +++ b/fftools/ffplay.c
> @@ -1925,16 +1925,24 @@ static int configure_video_filters(AVFilterGraph *graph, VideoState *is, const c
>           theta = get_rotation(displaymatrix);
>   
>           if (fabs(theta - 90) < 1.0) {
> -            INSERT_FILT("transpose", "clock");
> +            INSERT_FILT("transpose", displaymatrix[3] > 0 ? "cclock_flip" : "clock");
>           } else if (fabs(theta - 180) < 1.0) {
> -            INSERT_FILT("hflip", NULL);
> -            INSERT_FILT("vflip", NULL);
> +            if (displaymatrix[0] < 0) {
> +                INSERT_FILT("hflip", NULL);
> +            }
> +            if (displaymatrix[4] < 0) {
> +                INSERT_FILT("vflip", NULL);
> +            }
Minor code style point, we don't use {} if there's only one line inside 
the braces.


>           } else if (fabs(theta - 270) < 1.0) {
> -            INSERT_FILT("transpose", "cclock");
> +            INSERT_FILT("transpose", displaymatrix[3] < 0 ? "clock_flip" : "cclock");
>           } else if (fabs(theta) > 1.0) {
>               char rotate_buf[64];
>               snprintf(rotate_buf, sizeof(rotate_buf), "%f*PI/180", theta);
>               INSERT_FILT("rotate", rotate_buf);
> +        } else if (fabs(theta) < 1.0) {
> +            if (displaymatrix && displaymatrix[4] < 0) { > +                INSERT_FILT("vflip", NULL);
> +            }
>           }
>       }
>   

Otherwise looks mathematically sound.

- Leo Izen (thebombzen)
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