avfilter/vf_overlay: split blend_image into functions for each overlay format

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavfilter/vf_overlay.c

@@ -132,6 +132,8 @@ typedef struct OverlayContext {
     int eof_action;             ///< action to take on EOF from source
 
     AVExpr *x_pexpr, *y_pexpr;
+
+    void (*blend_image)(AVFilterContext *ctx, AVFrame *dst, const AVFrame *src, int x, int y);
 } OverlayContext;
 
 static av_cold void uninit(AVFilterContext *ctx)
@@ -304,22 +306,6 @@ static const enum AVPixelFormat alpha_pix_fmts[] = {
     AV_PIX_FMT_BGRA, AV_PIX_FMT_NONE
 };
 
-static int config_input_main(AVFilterLink *inlink)
-{
-    OverlayContext *s = inlink->dst->priv;
-    const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
-
-    av_image_fill_max_pixsteps(s->main_pix_step,    NULL, pix_desc);
-
-    s->hsub = pix_desc->log2_chroma_w;
-    s->vsub = pix_desc->log2_chroma_h;
-
-    s->main_is_packed_rgb =
-        ff_fill_rgba_map(s->main_rgba_map, inlink->format) >= 0;
-    s->main_has_alpha = ff_fmt_is_in(inlink->format, alpha_pix_fmts);
-    return 0;
-}
-
 static int config_input_overlay(AVFilterLink *inlink)
 {
     AVFilterContext *ctx  = inlink->dst;
@@ -397,22 +383,17 @@ static int config_output(AVFilterLink *outlink)
 /**
  * Blend image in src to destination buffer dst at position (x, y).
  */
-static void blend_image(AVFilterContext *ctx,
+
+static void blend_image_packed_rgb(AVFilterContext *ctx,
                                    AVFrame *dst, const AVFrame *src,
                                    int x, int y)
 {
     OverlayContext *s = ctx->priv;
-    int i, imax, j, jmax, k, kmax;
+    int i, imax, j, jmax;
     const int src_w = src->width;
     const int src_h = src->height;
     const int dst_w = dst->width;
     const int dst_h = dst->height;
-
-    if (x >= dst_w || x+src_w < 0 ||
-        y >= dst_h || y+src_h < 0)
-        return; /* no intersection */
-
-    if (s->main_is_packed_rgb) {
     uint8_t alpha;          ///< the amount of overlay to blend on to main
     const int dr = s->main_rgba_map[R];
     const int dg = s->main_rgba_map[G];
@@ -425,7 +406,7 @@ static void blend_image(AVFilterContext *ctx,
     const int sa = s->overlay_rgba_map[A];
     const int sstep = s->overlay_pix_step[0];
     const int main_has_alpha = s->main_has_alpha;
-        uint8_t *s, *sp, *d, *dp;
+    uint8_t *S, *sp, *d, *dp;
 
     i = FFMAX(-y, 0);
     sp = src->data[0] + i     * src->linesize[0];
@@ -433,11 +414,11 @@ static void blend_image(AVFilterContext *ctx,
 
     for (imax = FFMIN(-y + dst_h, src_h); i < imax; i++) {
         j = FFMAX(-x, 0);
-            s = sp + j     * sstep;
+        S = sp + j     * sstep;
         d = dp + (x+j) * dstep;
 
         for (jmax = FFMIN(-x + dst_w, src_w); j < jmax; j++) {
-                alpha = s[sa];
+            alpha = S[sa];
 
             // if the main channel has an alpha channel, alpha has to be calculated
             // to create an un-premultiplied (straight) alpha value
@@ -450,37 +431,49 @@ static void blend_image(AVFilterContext *ctx,
             case 0:
                 break;
             case 255:
-                    d[dr] = s[sr];
-                    d[dg] = s[sg];
-                    d[db] = s[sb];
+                d[dr] = S[sr];
+                d[dg] = S[sg];
+                d[db] = S[sb];
                 break;
             default:
                 // main_value = main_value * (1 - alpha) + overlay_value * alpha
                 // since alpha is in the range 0-255, the result must divided by 255
-                    d[dr] = FAST_DIV255(d[dr] * (255 - alpha) + s[sr] * alpha);
-                    d[dg] = FAST_DIV255(d[dg] * (255 - alpha) + s[sg] * alpha);
-                    d[db] = FAST_DIV255(d[db] * (255 - alpha) + s[sb] * alpha);
+                d[dr] = FAST_DIV255(d[dr] * (255 - alpha) + S[sr] * alpha);
+                d[dg] = FAST_DIV255(d[dg] * (255 - alpha) + S[sg] * alpha);
+                d[db] = FAST_DIV255(d[db] * (255 - alpha) + S[sb] * alpha);
             }
             if (main_has_alpha) {
                 switch (alpha) {
                 case 0:
                     break;
                 case 255:
-                        d[da] = s[sa];
+                    d[da] = S[sa];
                     break;
                 default:
                     // apply alpha compositing: main_alpha += (1-main_alpha) * overlay_alpha
-                        d[da] += FAST_DIV255((255 - d[da]) * s[sa]);
+                    d[da] += FAST_DIV255((255 - d[da]) * S[sa]);
                 }
             }
             d += dstep;
-                s += sstep;
+            S += sstep;
         }
         dp += dst->linesize[0];
         sp += src->linesize[0];
     }
-    } else {
+}
+
+static void blend_image_yuv(AVFilterContext *ctx,
+                            AVFrame *dst, const AVFrame *src,
+                            int x, int y)
+{
+    OverlayContext *s = ctx->priv;
+    int i, imax, j, jmax, k, kmax;
+    const int src_w = src->width;
+    const int src_h = src->height;
+    const int dst_w = dst->width;
+    const int dst_h = dst->height;
     const int main_has_alpha = s->main_has_alpha;
+
     if (main_has_alpha) {
         uint8_t alpha;          ///< the amount of overlay to blend on to main
         uint8_t *s, *sa, *d, *da;
@@ -582,7 +575,32 @@ static void blend_image(AVFilterContext *ctx,
             ap += (1 << vsub) * src->linesize[3];
         }
     }
+}
+
+static int config_input_main(AVFilterLink *inlink)
+{
+    OverlayContext *s = inlink->dst->priv;
+    const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
+
+    av_image_fill_max_pixsteps(s->main_pix_step,    NULL, pix_desc);
+
+    s->hsub = pix_desc->log2_chroma_w;
+    s->vsub = pix_desc->log2_chroma_h;
+
+    s->main_is_packed_rgb =
+        ff_fill_rgba_map(s->main_rgba_map, inlink->format) >= 0;
+    s->main_has_alpha = ff_fmt_is_in(inlink->format, alpha_pix_fmts);
+    switch (s->format) {
+    case OVERLAY_FORMAT_YUV420:
+    case OVERLAY_FORMAT_YUV422:
+    case OVERLAY_FORMAT_YUV444:
+        s->blend_image = blend_image_yuv;
+        break;
+    case OVERLAY_FORMAT_RGB:
+        s->blend_image = blend_image_packed_rgb;
+        break;
     }
+    return 0;
 }
 
 static AVFrame *do_blend(AVFilterContext *ctx, AVFrame *mainpic,
@@ -611,7 +629,9 @@ static AVFrame *do_blend(AVFilterContext *ctx, AVFrame *mainpic,
                s->var_values[VAR_Y], s->y);
     }
 
-    blend_image(ctx, mainpic, second, s->x, s->y);
+    if (s->x < mainpic->width  && s->x + second->width  >= 0 ||
+        s->y < mainpic->height && s->y + second->height >= 0)
+        s->blend_image(ctx, mainpic, second, s->x, s->y);
     return mainpic;
 }