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};
diff --git a/sub/img_convert.h b/sub/img_convert.h
index 5dc7fc2e90..85ba5bb828 100644
--- a/sub/img_convert.h
+++ b/sub/img_convert.h
@@ -12,9 +12,7 @@ struct osd_conv_cache *osd_conv_cache_new(void);
 // These functions convert from one OSD format to another. On success, they copy
 // the converted image data into c, and change imgs to point to the data.
 bool osd_conv_idx_to_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs);
-bool osd_conv_idx_to_rgba_str(struct osd_conv_cache *c, struct sub_bitmaps *imgs);
 bool osd_conv_ass_to_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs);
-bool osd_conv_ass_to_rgba_str(struct osd_conv_cache *c, struct sub_bitmaps *imgs);
 // Sub postprocessing
 bool osd_conv_blur_rgba(struct osd_conv_cache *c, struct sub_bitmaps *imgs,
                         double gblur);
diff --git a/sub/sub.c b/sub/sub.c
index 0e297e3bf8..a5ff9e2593 100644
--- a/sub/sub.c
+++ b/sub/sub.c
@@ -202,23 +202,13 @@ static void render_object(struct osd_state *osd, struct osd_object *obj,
     if (formats[SUBBITMAP_RGBA] && out_imgs->format == SUBBITMAP_INDEXED)
         cached |= osd_conv_idx_to_rgba(obj->cache[1], out_imgs);
 
-    if (formats[SUBBITMAP_RGBA_STR] && out_imgs->format == SUBBITMAP_INDEXED)
-        cached |= osd_conv_idx_to_rgba_str(obj->cache[1], out_imgs);
-
-    if ((out_imgs->format == SUBBITMAP_RGBA ||
-         out_imgs->format == SUBBITMAP_RGBA_STR)
-        && opts->sub_gauss != 0.0f)
-    {
+    if (out_imgs->format == SUBBITMAP_RGBA && opts->sub_gauss != 0.0f)
         cached |= osd_conv_blur_rgba(obj->cache[2], out_imgs, opts->sub_gauss);
-    }
 
     // Do this conversion last to not trigger gauss blurring for ASS
     if (formats[SUBBITMAP_RGBA] && out_imgs->format == SUBBITMAP_LIBASS)
         cached |= osd_conv_ass_to_rgba(obj->cache[3], out_imgs);
 
-    if (formats[SUBBITMAP_RGBA_STR] && out_imgs->format == SUBBITMAP_LIBASS)
-        cached |= osd_conv_ass_to_rgba_str(obj->cache[3], out_imgs);
-
     if (cached)
         obj->cached = *out_imgs;
 }
diff --git a/sub/sub.h b/sub/sub.h
index 3463022c88..3cb140565c 100644
--- a/sub/sub.h
+++ b/sub/sub.h
@@ -25,12 +25,11 @@
 
 #include "mpvcore/m_option.h"
 
-// NOTE: VOs must support at least SUBBITMAP_RGBA or SUBBITMAP_RGBA_STR.
+// NOTE: VOs must support at least SUBBITMAP_RGBA.
 enum sub_bitmap_format {
     SUBBITMAP_EMPTY = 0,// no bitmaps; always has num_parts==0
     SUBBITMAP_LIBASS,   // A8, with a per-surface blend color (libass.color)
     SUBBITMAP_RGBA,     // B8G8R8A8 (MSB=A, LSB=B), scaled, premultiplied alpha
-    SUBBITMAP_RGBA_STR, // like RGBA, but straight (not premultiplied) alpha
     SUBBITMAP_INDEXED,  // scaled, bitmap points to osd_bmp_indexed
 
     SUBBITMAP_COUNT
@@ -39,7 +38,8 @@ enum sub_bitmap_format {
 // For SUBBITMAP_INDEXED
 struct osd_bmp_indexed {
     uint8_t *bitmap;
-    // Each entry is like a pixel in SUBBITMAP_RGBA_STR format.
+    // Each entry is like a pixel in SUBBITMAP_RGBA format, but using straight
+    // alpha.
     uint32_t palette[256];
 };
 
diff --git a/video/out/vo_vaapi.c b/video/out/vo_vaapi.c
index 48eac61b9b..e41e1a9c56 100644
--- a/video/out/vo_vaapi.c
+++ b/video/out/vo_vaapi.c
@@ -125,7 +125,7 @@ struct priv {
 static const bool osd_formats[SUBBITMAP_COUNT] = {
     // Actually BGRA, but only on little endian.
     // This will break on big endian, I think.
-    [SUBBITMAP_RGBA_STR] = true,
+    [SUBBITMAP_RGBA] = true,
 };
 
 struct fmtentry {