subs, vo: do sub bitmap change detection by comparing IDs

vo_vdpau and vo_gl cache the last subtitle bitmaps uploaded to video
card in case they stay the same over multiple frames. Detecting
whether the bitmaps have changed and should be re-uploaded was
somewhat fragile. Change the VO API to provide a bitmap ID which can
be compared with what the VO has to determine whether a new upload of
the bitmaps is needed.

Conflicts:
	libvo/vo_gl.c

Note: the changes for vo_gl.c were not merged. Instead, eosd_packer is
modified to use the new way of detecting EOSD changes. This takes care
of vo_gl, vo_gl3 and vo_direct3d, which all render EOSD. They don't
need to be updated in turn.

libmpcodecs/vf_vo.c

@@ -34,7 +34,6 @@
 
 struct vf_priv_s {
     struct vo *vo;
-    bool prev_visibility;
     double scale_ratio;
 };
 #define video_out (vf->priv->vo)
@@ -77,9 +76,6 @@ static int config(struct vf_instance *vf,
 
     vf->priv->scale_ratio = (double) d_width / d_height * height / width;
 
-    // force EOSD change detection reset
-    vf->priv->prev_visibility = false;
-
     return 1;
 }
 
@@ -121,27 +117,17 @@ static int control(struct vf_instance *vf, int request, void *data)
         };
         return vo_control(video_out, VOCTRL_GET_EQUALIZER, &param) == VO_TRUE;
     }
-    case VFCTRL_INIT_EOSD: {
-        vf->priv->prev_visibility = false;
-        return CONTROL_TRUE;
-    }
-
     case VFCTRL_DRAW_EOSD: {
         struct osd_state *osd = data;
         osd->dim = (struct mp_eosd_res){0};
         if (!video_out->config_ok ||
-                vo_control(video_out, VOCTRL_GET_EOSD_RES, &osd->dim) != true) {
+                vo_control(video_out, VOCTRL_GET_EOSD_RES, &osd->dim) != true)
-            vf->priv->prev_visibility = false;
             return CONTROL_FALSE;
-        }
         osd->normal_scale = 1;
         osd->vsfilter_scale = vf->priv->scale_ratio;
         osd->unscaled = vf->default_caps & VFCAP_EOSD_UNSCALED;
         struct sub_bitmaps images;
         sub_get_bitmaps(osd, &images);
-        if (!vf->priv->prev_visibility)
-            images.changed = 2;
-        vf->priv->prev_visibility = true;
         return vo_control(video_out, VOCTRL_DRAW_EOSD, &images) == VO_TRUE;
     }
     }

libvo/eosd_packer.c

@@ -147,17 +147,18 @@ void eosd_packer_generate(struct eosd_packer *state, mp_eosd_images_t *imgs,
     ASS_Image *p;
     struct eosd_surface *sfc = &state->surface;
 
-    *out_need_reposition = false;
+    *out_need_reposition = imgs->bitmap_pos_id != state->last_bitmap_pos_id;
-    *out_need_upload = false;
+    *out_need_upload = imgs->bitmap_id != state->last_bitmap_id;
     *out_need_reallocate = false;
 
-    int change_state = imgs->changed;
+    state->last_bitmap_pos_id = imgs->bitmap_pos_id;
+    state->last_bitmap_id = imgs->bitmap_id;
 
     // eosd_reinit() was probably called, force full reupload.
     if (state->targets_count == 0 && img)
-        change_state = 2;
+        *out_need_upload = true;
 
-    if (change_state == 0)
+    if (!(*out_need_reposition) && !(*out_need_upload))
         return; // Nothing changed, no need to redraw
 
     state->targets_count = 0;
@@ -167,7 +168,7 @@ void eosd_packer_generate(struct eosd_packer *state, mp_eosd_images_t *imgs,
     if (!img)
         return; // There's nothing to render!
 
-    if (change_state == 1)
+    if (!(*out_need_upload))
         goto eosd_skip_upload;
 
     *out_need_upload = true;

libvo/eosd_packer.h

@@ -58,6 +58,8 @@ struct eosd_packer {
     uint32_t max_surface_height;
 
     int *scratch;
+    int last_bitmap_id;
+    int last_bitmap_pos_id;
 };
 
 struct eosd_packer *eosd_packer_create(void *talloc_ctx);

libvo/vo_vdpau.c

@@ -186,6 +186,8 @@ struct vdpctx {
     } *eosd_targets, osd_targets[MAX_OLD_OSD_BITMAPS][2];
     int eosd_targets_size;
     int eosd_render_count;
+    int bitmap_id;
+    int bitmap_pos_id;
 
     // Video equalizer
     struct mp_csp_equalizer video_eq;
@@ -812,6 +814,7 @@ static void mark_vdpau_objects_uninitialized(struct vo *vo)
     vc->vdp_device = VDP_INVALID_HANDLE;
     talloc_free(vc->osd_surface.packer);
     talloc_free(vc->eosd_surface.packer);
+    vc->bitmap_id = vc->bitmap_pos_id = 0;
     vc->osd_surface = vc->eosd_surface = (struct eosd_bitmap_surface){
         .surface = VDP_INVALID_HANDLE,
     };
@@ -999,7 +1002,7 @@ static void generate_eosd(struct vo *vo, mp_eosd_images_t *imgs)
     struct eosd_bitmap_surface *sfc = &vc->eosd_surface;
     bool need_upload = false;
 
-    if (imgs->changed == 0 && sfc->packer)
+    if (imgs->bitmap_pos_id == vc->bitmap_pos_id)
         return; // Nothing changed and we still have the old data
 
     vc->eosd_render_count = 0;
@@ -1007,7 +1010,7 @@ static void generate_eosd(struct vo *vo, mp_eosd_images_t *imgs)
     if (!imgs->imgs)
         return; // There's nothing to render!
 
-    if (imgs->changed == 1)
+    if (imgs->bitmap_id == vc->bitmap_id)
         goto eosd_skip_upload;
 
     need_upload = true;
@@ -1069,6 +1072,8 @@ eosd_skip_upload:
         target->dest.y1 = p->h + p->dst_y;
         vc->eosd_render_count++;
     }
+    vc->bitmap_id = imgs->bitmap_id;
+    vc->bitmap_pos_id = imgs->bitmap_pos_id;
 }
 
 static void record_osd(void *ctx, int x0, int y0, int w, int h,

sub/dec_sub.c

@@ -45,7 +45,7 @@ void sub_init(struct sh_sub *sh, struct osd_state *osd)
         if (sh->sd_driver->init(sh, osd) < 0)
             return;
         osd->sh_sub = sh;
-        osd->changed_outside_sd = true;
+        osd->bitmap_id = ++osd->bitmap_pos_id;
         sh->initialized = true;
         sh->active = true;
     }
@@ -62,16 +62,23 @@ void sub_get_bitmaps(struct osd_state *osd, struct sub_bitmaps *res)
 {
     struct MPOpts *opts = osd->opts;
 
-    *res = (struct sub_bitmaps){.imgs = NULL, .changed = 2};
+    *res = (struct sub_bitmaps){ .bitmap_id = osd->bitmap_id,
+                                 .bitmap_pos_id = osd->bitmap_pos_id };
     if (!opts->sub_visibility || !osd->sh_sub || !osd->sh_sub->active) {
-        osd->changed_outside_sd = true;
+        /* Change ID in case we just switched from visible subtitles
+         * to current state. Hopefully, unnecessarily claiming that
+         * things may have changed is harmless for empty contents.
+         * Increase osd-> values ahead so that _next_ returned id
+         * is also guaranteed to differ from this one.
+         */
+        res->bitmap_id = ++res->bitmap_pos_id;
+        osd->bitmap_id = osd->bitmap_pos_id += 2;
         return;
     }
     if (osd->sh_sub->sd_driver->get_bitmaps)
         osd->sh_sub->sd_driver->get_bitmaps(osd->sh_sub, osd, res);
-    if (osd->changed_outside_sd)
+    osd->bitmap_id = res->bitmap_id;
-        res->changed = 2;
+    osd->bitmap_pos_id = res->bitmap_pos_id;
-    osd->changed_outside_sd = false;
 }
 
 void sub_reset(struct sh_sub *sh, struct osd_state *osd)

sub/dec_sub.h

@@ -12,7 +12,7 @@ typedef struct mp_eosd_res {
 
 typedef struct sub_bitmaps {
     struct ass_image *imgs;
-    int changed;
+    int bitmap_id, bitmap_pos_id;
 } mp_eosd_images_t;
 
 static inline bool is_text_sub(int type)

sub/sd_ass.c

@@ -140,8 +140,13 @@ static void get_bitmaps(struct sh_sub *sh, struct osd_state *osd,
     ASS_Renderer *renderer = osd->ass_renderer;
     mp_ass_configure(renderer, opts, &osd->dim, osd->unscaled);
     ass_set_aspect_ratio(renderer, scale, 1);
+    int changed;
     res->imgs = ass_render_frame(renderer, ctx->ass_track,
-                                 osd->sub_pts * 1000 + .5, &res->changed);
+                                 osd->sub_pts * 1000 + .5, &changed);
+    if (changed == 2)
+        res->bitmap_id = ++res->bitmap_pos_id;
+    else if (changed)
+        res->bitmap_pos_id++;
 }
 
 static void reset(struct sh_sub *sh, struct osd_state *osd)

sub/sub.h

@@ -63,7 +63,8 @@ struct osd_state {
     struct ass_library *ass_library;
     struct ass_renderer *ass_renderer;
     struct sh_sub *sh_sub;
-    bool changed_outside_sd;
+    int bitmap_id;
+    int bitmap_pos_id;
     double sub_pts;
     double sub_offset;
     struct mp_eosd_res dim;