[FFmpeg-devel] [PATCH] ffplay: Use sws_scale to scale subtitles

[Marton Balint]

On Tue, 28 Jul 2015, Michael Niedermayer wrote:

> From: Michael Niedermayer <michael at niedermayer.cc>
>
> Fixes some files from Ticket679
>
> This also changes subtitles to 4:2:0 matching the output format and thus
> simplifying the blend code.
> This restricts placement to the chroma sample resolution though, speak up
> if you consider this a problem, say so, the code could be changed to use
> YUV444 for subtitles and scaling them down while blending, this would be
> slower though.
> The current code only uses a single swscale context and reinitializes it
> as needed, this could be changed as well if needed
>
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
> ffplay.c |  284 ++++++++++++++++----------------------------------------------
> 1 file changed, 71 insertions(+), 213 deletions(-)
>

[...]

> @@ -2348,14 +2176,41 @@ static int subtitle_thread(void *arg)
>
>             for (i = 0; i < sp->sub.num_rects; i++)
>             {
> -                for (j = 0; j < sp->sub.rects[i]->nb_colors; j++)
> -                {
> -                    RGBA_IN(r, g, b, a, (uint32_t*)sp->sub.rects[i]->pict.data[1] + j);
> -                    y = RGB_TO_Y_CCIR(r, g, b);
> -                    u = RGB_TO_U_CCIR(r, g, b, 0);
> -                    v = RGB_TO_V_CCIR(r, g, b, 0);
> -                    YUVA_OUT((uint32_t*)sp->sub.rects[i]->pict.data[1] + j, y, u, v, a);
> +                int in_w = sp->sub.rects[i]->w;
> +                int in_h = sp->sub.rects[i]->h;
> +                int subw = is->subdec.avctx->width  ? is->subdec.avctx->width  : is->viddec_width;
> +                int subh = is->subdec.avctx->height ? is->subdec.avctx->height : is->viddec_height;
> +                int out_w = in_w * is->viddec_width  / subw;
> +                int out_h = in_h * is->viddec_height / subh;

You should check for zero viddec_width/height here. E.g.:
out_w = is->viddec_width  ? in_w * is->viddec_width  / subw : in_w;
out_h = is->viddec_height ? in_h * is->viddec_height / subh : in_h;

Otherwise LGTM.

Thanks,
Marton