[FFmpeg-devel] [PATCH] avfilter: add panorama filter

[Paul B Mahol]

On 3/12/18, Hazem Ashmawy <hazem.s.ashmawy at gmail.com> wrote:
> So, I spend few hours trying to incorporate the partial change.
>
> I'm not sure that the video sent by <jamrial> earlier follows the
> faces order here
> https://github.com/google/spatial-media/blob/master/docs/spherical-video-v2-rfc.md#semantics-3
>
> Because when I made this change, I got a reasonable equirectangular ouput:
> https://imgur.com/a/BEN00
>
> comparing to the changes sent earlier.
> https://imgur.com/a/vaIvW
>
> diff --git a/libavfilter/vf_panorama.c b/libavfilter/vf_panorama.c
> index de08ef4..5383d57 100644
> --- a/libavfilter/vf_panorama.c
> +++ b/libavfilter/vf_panorama.c
> @@ -34,12 +34,12 @@ enum Projections {
>  };
>
>  enum Faces {
> +    DOWN,
>      LEFT,
> +    TOP,
>      FRONT,
>      RIGHT,
> -    TOP,
>      BACK,
> -    DOWN,
>  };
>
>  struct XYRemap {
> @@ -403,7 +403,7 @@ static int config_output(AVFilterLink *outlink)
>
>                      switch (face) {
>                      case LEFT:
> -                        locate(z, x, y, M_PI,   rw, rh, &ox, &oy);
> +                        locate(z, x, y, -M_PI_2,   rw, rh, &ox, &oy);
>                          break;
>                      case FRONT:
>                          locate(x, z, y, 0.,     rw, rh, &ox, &oy);
> @@ -418,7 +418,7 @@ static int config_output(AVFilterLink *outlink)
>                          locate(x, y, z,-M_PI_2, rw, rh, &ox, &oy);
>                          break;
>                      case DOWN:
> -                        locate(y, x, z,-M_PI_2, rw, rh, &ox, &oy);
> +                        locate(y, x, z, M_PI_2, rw, rh, &ox, &oy);
>                          break;
>                      }
>
> What I'm saying is: when I changed face order to this (which video
> sample seems to follow), I got a reasonable output.
> down | left | top
> front | right | back
>
> Comparing to Google's:
> right | left | top
> down | front | back

The video linked here does not have name of faces, so you can not know
what is front and what is back.

Just add support for typical cubemap layout currently used.