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

[Marton Balint]

On Sun, 26 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

It is fine by me as it is.

> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
> ffplay.c |  275 ++++++++++++++------------------------------------------------
> 1 file changed, 62 insertions(+), 213 deletions(-)
>

[...]

>     for (;;) {
>         if (!(sp = frame_queue_peek_writable(&is->subpq)))
> @@ -2348,14 +2170,41 @@ 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.avctx->width;
> +                int subh = is->subdec.avctx->height ? is->subdec.avctx->height : is->viddec.avctx->height;
> +                int out_w = in_w * is->viddec.avctx->width  / subw;
> +                int out_h = in_h * is->viddec.avctx->height / subh;

viddec.avctx may not be set here. I see no better way but to add two extra 
fields to VideoState and update them when opening a video stream and when 
decoding a new picture.

> +                AVPicture newpic;
> +
> +                //cant use avpicture_alloc as it is not compatible with avsubtitle_free()
> +                av_image_fill_linesizes(newpic.linesize, AV_PIX_FMT_YUVA420P, out_w);
> +                newpic.data[0] = av_malloc(newpic.linesize[0] * out_h);
> +                newpic.data[3] = av_malloc(newpic.linesize[3] * out_h);
> +                newpic.data[1] = av_malloc(newpic.linesize[1] * ((out_h+1)/2));
> +                newpic.data[2] = av_malloc(newpic.linesize[2] * ((out_h+1)/2));
> +
> +                is->sub_convert_ctx = sws_getCachedContext(is->sub_convert_ctx,
> +                    in_w, in_h, AV_PIX_FMT_PAL8, out_w, out_h,
> +                    AV_PIX_FMT_YUVA420P, sws_flags, NULL, NULL, NULL);
> +                if (!is->sub_convert_ctx || !newpic.data[0] || !newpic.data[3] ||
> +                    !newpic.data[1] || !newpic.data[2]
> +                ) {
> +                    av_log(NULL, AV_LOG_FATAL, "Cannot initialize the sub conversion context\n");
> +                    exit(1);
>                 }
> +                sws_scale(is->sub_convert_ctx,
> +                          sp->sub.rects[i]->pict.data, sp->sub.rects[i]->pict.linesize,
> +                          0, in_h, newpic.data, newpic.linesize);
> +
> +                av_free(sp->sub.rects[i]->pict.data[0]);
> +                av_free(sp->sub.rects[i]->pict.data[1]);
> +                sp->sub.rects[i]->pict = newpic;
> +                sp->sub.rects[i]->w = out_w;
> +                sp->sub.rects[i]->h = out_h;
> +                sp->sub.rects[i]->x = sp->sub.rects[i]->x * out_w / in_w;
> +                sp->sub.rects[i]->y = sp->sub.rects[i]->y * out_h / in_h;
>             }
>

Regards,
Marton