sub: never decode subs to old OSD format

Instead, sd_lavc.c and spudec.c (the two image sub decoders) always
output indexed/paletted images. For this purpose, add SUBBITMAP_INDEXED,
and convert the subs to RGBA in img_convert.c instead. If a VO is used
that supports the old OSD format only, the indexed bitmaps are converted
to the old OSD format by abusing spudec.c in a similar way sd_lavc.c
used to do.

The main reason why spudec.c is used is because the images must not only
be converted to the old format, but also properly scaled, cropped, and
aligned (the asm code in libvo/osd.c requires this alignment).

Remove support for the old format (packed variant) from the OpenGL VOs.
(The packed formats were how the actual OSD format was handled in some
GPU-driven VOs for a while.)

Remove all conversions from old to new formats. Now all subtitle
decoders and OSD renderers produce the new formats only.

Add an evil hack to convert the new format (scaled+indexed bitmaps) to
the old format. It creates a new spudec instance to convert images to
grayscale and to scale them. This is temporary for VOs which don't
support new OSD formats yet (vo_xv, vo_x11, vo_lavc).

1 files changed, 17 insertions, 7 deletions

diff --git a/sub/sub.h b/sub/sub.h
index 6a83036460..8649018029 100644
--- a/sub/sub.h
+++ b/sub/sub.h
@@ -30,13 +30,20 @@ struct sub_render_params;
 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, can be scaled
-    SUBBITMAP_OLD,      // I8A8 (monochrome), premultiplied alpha
+    SUBBITMAP_RGBA,     // B8G8R8A8 (MSB=A, LSB=B), can be scaled
+    SUBBITMAP_INDEXED,  // scaled, bitmap points to osd_bmp_indexed
     SUBBITMAP_OLD_PLANAR, // like previous, but bitmap points to old_osd_planar
 
     SUBBITMAP_COUNT
 };
 
+// For SUBBITMAP_INDEXED
+struct osd_bmp_indexed {
+    uint8_t *bitmap;
+    // Each entry is like a pixel in SUBBITMAP_RGBA format
+    uint32_t palette[256];
+};
+
 // For SUBBITMAP_OLD_PANAR
 struct old_osd_planar {
     unsigned char *bitmap;
@@ -46,9 +53,10 @@ struct old_osd_planar {
 struct sub_bitmap {
     void *bitmap;
     int stride;
+    // Note: not clipped, going outside the screen area is allowed
+    //       (except for SUBBITMAP_LIBASS, which is always clipped)
     int w, h;
     int x, y;
-    // Note: not clipped, going outside the screen area is allowed
     int dw, dh;
 
     union {
@@ -59,10 +67,14 @@ struct sub_bitmap {
 };
 
 struct sub_bitmaps {
-    int render_index;   // for VO cache state (limited by MAX_OSD_PARTS)
+    // For VO cache state (limited by MAX_OSD_PARTS)
+    int render_index;
 
     enum sub_bitmap_format format;
-    bool scaled;        // if false, dw==w && dh==h
+
+    // If false, dw==w && dh==h.
+    // SUBBITMAP_LIBASS is never scaled.
+    bool scaled;
 
     struct sub_bitmap *parts;
     int num_parts;
@@ -120,8 +132,6 @@ struct osd_state {
     double sub_offset;
     double vo_sub_pts;
 
-    bool support_rgba;
-
     bool render_subs_in_filter;
 
     struct mp_eosd_res res;