Revert "sub: support straight alpha additionally to premultiplied alpha"

This reverts commit 689a25003fc8098e5fdfbb2faefc0e18365d3acb, with some
adjustments to code that was added after that commit.

I just messed up big time. We don't need this, and in fact the commit
confused straight and premultiplied alpha at one point (just a simple
inverted condition due to an oversight), which is why it looked like
it was working.

In commit 2827295 I wrote:

   Also, libva can't decide whether it accepts straight or premultiplied
   alpha for OSD sub-pictures [...]

That was just me messing up and being severely confused by my own bugs.
VA API  uses premultiplied alpha, which by the way is nice and
thoughtful of the VA API devs.

Well, this was stupid. But in the end, I'm glad that I could actually
reduce codesize by a good amount again.

1 files changed, 13 insertions, 76 deletions

diff --git a/sub/img_convert.c b/sub/img_convert.c
index 35215a7522..3ebe993c17 100644
--- a/sub/img_convert.c
+++ b/sub/img_convert.c
@@ -56,14 +56,13 @@ static void rgba_to_premultiplied_rgba(uint32_t *colors, size_t count)
     }
 }
 
-static bool conv_idx_to_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs,
-                             bool straight_alpha)
+bool osd_conv_idx_to_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs)
 {
     struct sub_bitmaps src = *imgs;
     if (src.format != SUBBITMAP_INDEXED)
         return false;
 
-    imgs->format = straight_alpha ? SUBBITMAP_RGBA_STR : SUBBITMAP_RGBA;
+    imgs->format = SUBBITMAP_RGBA;
     talloc_free(c->parts);
     imgs->parts = c->parts = talloc_array(c, struct sub_bitmap, src.num_parts);
 
@@ -72,8 +71,7 @@ static bool conv_idx_to_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs,
         struct sub_bitmap *s = &src.parts[n];
         struct osd_bmp_indexed sb = *(struct osd_bmp_indexed *)s->bitmap;
 
-        if (imgs->format == SUBBITMAP_RGBA)
-            rgba_to_premultiplied_rgba(sb.palette, 256);
+        rgba_to_premultiplied_rgba(sb.palette, 256);
 
         *d = *s;
         struct mp_image *image = mp_image_alloc(IMGFMT_BGRA, s->w, s->h);
@@ -91,21 +89,11 @@ static bool conv_idx_to_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs,
     return true;
 }
 
-bool osd_conv_idx_to_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs)
-{
-    return conv_idx_to_rgba(c, imgs, false);
-}
-
-bool osd_conv_idx_to_rgba_str(struct osd_conv_cache *c, struct sub_bitmaps *imgs)
-{
-    return conv_idx_to_rgba(c, imgs, true);
-}
-
 bool osd_conv_blur_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs,
                         double gblur)
 {
     struct sub_bitmaps src = *imgs;
-    if (src.format != SUBBITMAP_RGBA && src.format != SUBBITMAP_RGBA_STR)
+    if (src.format != SUBBITMAP_RGBA)
         return false;
 
     talloc_free(c->parts);
@@ -146,7 +134,7 @@ bool osd_conv_blur_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs,
 bool osd_scale_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs)
 {
     struct sub_bitmaps src = *imgs;
-    if (src.format != SUBBITMAP_RGBA && src.format != SUBBITMAP_RGBA_STR)
+    if (src.format != SUBBITMAP_RGBA)
         return false;
 
     bool need_scale = false;
@@ -222,8 +210,8 @@ bool osd_conv_idx_to_gray(struct osd_conv_cache *c, struct sub_bitmaps *imgs)
     return true;
 }
 
-static void draw_ass_rgba(uint8_t *src, int src_w, int src_h,
-                          int src_stride, uint8_t *dst, size_t dst_stride,
+static void draw_ass_rgba(unsigned char *src, int src_w, int src_h,
+                          int src_stride, unsigned char *dst, size_t dst_stride,
                           int dst_x, int dst_y, uint32_t color)
 {
     const unsigned int r = (color >> 24) & 0xff;
@@ -255,41 +243,7 @@ static void draw_ass_rgba(uint8_t *src, int src_w, int src_h,
     }
 }
 
-static void draw_ass_rgba_str(uint8_t *src, int src_w, int src_h,
-                              int src_stride, uint8_t *dst, size_t dst_stride,
-                              int dst_x, int dst_y, uint32_t color)
-{
-    const unsigned int r = (color >> 24) & 0xff;
-    const unsigned int g = (color >> 16) & 0xff;
-    const unsigned int b = (color >>  8) & 0xff;
-    const unsigned int a = 0xff - (color & 0xff);
-
-    dst += dst_y * dst_stride + dst_x * 4;
-
-    for (int y = 0; y < src_h; y++, dst += dst_stride, src += src_stride) {
-        uint32_t *dstrow = (uint32_t *) dst;
-        for (int x = 0; x < src_w; x++) {
-            const unsigned int v = src[x];
-            int rr = (r * v);
-            int gg = (g * v);
-            int bb = (b * v);
-            int aa = (a * v);
-            uint32_t dstpix = dstrow[x];
-            unsigned int dstb =  dstpix        & 0xFF;
-            unsigned int dstg = (dstpix >>  8) & 0xFF;
-            unsigned int dstr = (dstpix >> 16) & 0xFF;
-            unsigned int dsta = (dstpix >> 24) & 0xFF;
-            dstb = (bb + dstb * (255 - aa)) / 255;
-            dstg = (gg + dstg * (255 - aa)) / 255;
-            dstr = (rr + dstr * (255 - aa)) / 255;
-            dsta = (aa + dsta * (255 - aa)) / 255;
-            dstrow[x] = dstb | (dstg << 8) | (dstr << 16) | (dsta << 24);
-        }
-    }
-}
-
-static bool conv_ass_to_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs,
-                             bool straight_alpha)
+bool osd_conv_ass_to_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs)
 {
     struct sub_bitmaps src = *imgs;
     if (src.format != SUBBITMAP_LIBASS)
@@ -299,7 +253,7 @@ static bool conv_ass_to_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs,
     struct mp_rect bb_list[MP_SUB_BB_LIST_MAX];
     int num_bb = mp_get_sub_bb_list(&src, bb_list, MP_SUB_BB_LIST_MAX);
 
-    imgs->format = straight_alpha ? SUBBITMAP_RGBA_STR : SUBBITMAP_RGBA;
+    imgs->format = SUBBITMAP_RGBA;
     imgs->parts = c->part;
     imgs->num_parts = num_bb;
 
@@ -342,33 +296,16 @@ static bool conv_ass_to_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs,
                 s->y > bb.y1 || s->y + s->h < bb.y0)
                 continue;
 
-            if (imgs->format == SUBBITMAP_RGBA_STR) {
-                draw_ass_rgba(s->bitmap, s->w, s->h, s->stride,
-                              bmp->bitmap, bmp->stride,
-                              s->x - bb.x0, s->y - bb.y0,
-                              s->libass.color);
-            } else {
-                draw_ass_rgba_str(s->bitmap, s->w, s->h, s->stride,
-                                  bmp->bitmap, bmp->stride,
-                                  s->x - bb.x0, s->y - bb.y0,
-                                  s->libass.color);
-            }
+            draw_ass_rgba(s->bitmap, s->w, s->h, s->stride,
+                          bmp->bitmap, bmp->stride,
+                          s->x - bb.x0, s->y - bb.y0,
+                          s->libass.color);
         }
     }
 
     return true;
 }
 
-bool osd_conv_ass_to_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs)
-{
-    return conv_ass_to_rgba(c, imgs, false);
-}
-
-bool osd_conv_ass_to_rgba_str(struct osd_conv_cache *c, struct sub_bitmaps *imgs)
-{
-    return conv_ass_to_rgba(c, imgs, true);
-}
-
 bool mp_sub_bitmaps_bb(struct sub_bitmaps *imgs, struct mp_rect *out_bb)
 {
     struct mp_rect bb = {INT_MAX, INT_MAX, INT_MIN, INT_MIN};