player: remove OSD subtitle render path

This was used with --no-sub-ass (aka --no-ass). This option (which is
not yet removed) strips all styling from the subtitles, and renders them
as plaintext only. For some reason, it originally seemed convenient to
reuse all the OSD text rendering code (osd_libass.c). While this was
indeed simple, it had a bad influence on the rest of the code. For
example, it had to decide whether to go through the OSD code path, or
the proper subtitle renderer in sd_ass.c.

Kill the OSD subtitle renderer. Reimplement --no-sub-ass and also
"secondary" subtitles in sd_ass.c. fill_plaintext() contains some rather
minor code duplication with osd_libass.c for setting up a dummy
ASS_Event and escaping the stripped text. Since sd_ass.c already has to
handle "normal" text subtitles, and has code for stripping ASS tags,
this remains all relatively simple.

Remove all the unnecessary crap from the rest of the code.

1 files changed, 65 insertions, 15 deletions

diff --git a/sub/sd_ass.c b/sub/sd_ass.c
index baec35faa9..804e561e87 100644
--- a/sub/sd_ass.c
+++ b/sub/sd_ass.c
@@ -37,7 +37,9 @@
 
 struct sd_ass_priv {
     struct ass_track *ass_track;
+    struct ass_track *shadow_track; // for --sub-ass=no rendering
     bool is_converted;
+    bool on_top;
     struct sub_bitmap *parts;
     bool flush_on_seek;
     int extend_event;
@@ -47,6 +49,7 @@ struct sd_ass_priv {
 };
 
 static void mangle_colors(struct sd *sd, struct sub_bitmaps *parts);
+static void fill_plaintext(struct sd *sd, double pts);
 
 static bool supports_format(const char *format)
 {
@@ -76,6 +79,11 @@ static int init(struct sd *sd)
     if (!ctx->is_converted)
         ctx->ass_track->track_type = TRACK_TYPE_ASS;
 
+    ctx->shadow_track = ass_new_track(sd->ass_library);
+    ctx->shadow_track->PlayResX = 384;
+    ctx->shadow_track->PlayResY = 288;
+    mp_ass_add_default_styles(ctx->shadow_track, opts);
+
     if (sd->extradata) {
         ass_process_codec_private(ctx->ass_track, sd->extradata,
                                   sd->extradata_len);
@@ -147,12 +155,11 @@ static void decode(struct sd *sd, struct demux_packet *packet)
     event->Text = strdup(text);
 }
 
-static void configure_ass(struct sd *sd, struct mp_osd_res *dim)
+static void configure_ass(struct sd *sd, struct mp_osd_res *dim,
+                          bool converted, ASS_Track *track)
 {
-    struct sd_ass_priv *ctx = sd->priv;
     struct MPOpts *opts = sd->opts;
     ASS_Renderer *priv = sd->ass_renderer;
-    ASS_Track *track = ctx->ass_track;
 
     ass_set_frame_size(priv, dim->w, dim->h);
     ass_set_margins(priv, dim->mt, dim->mb, dim->ml, dim->mr);
@@ -166,7 +173,7 @@ static void configure_ass(struct sd *sd, struct mp_osd_res *dim)
     bool set_scale_by_window = true;
     bool total_override = false;
     // With forced overrides, apply the --sub-* specific options
-    if (ctx->is_converted || opts->ass_style_override == 3) {
+    if (converted || opts->ass_style_override == 3) {
         set_scale_with_window = opts->sub_scale_with_window;
         set_use_margins = opts->sub_use_margins;
         set_scale_by_window = opts->sub_scale_by_window;
@@ -175,7 +182,7 @@ static void configure_ass(struct sd *sd, struct mp_osd_res *dim)
         set_scale_with_window = opts->ass_scale_with_window;
         set_use_margins = opts->ass_use_margins;
     }
-    if (ctx->is_converted || opts->ass_style_override) {
+    if (converted || opts->ass_style_override) {
         set_sub_pos = 100 - opts->sub_pos;
         set_line_spacing = opts->ass_line_spacing;
         set_hinting = opts->ass_hinting;
@@ -203,7 +210,7 @@ static void configure_ass(struct sd *sd, struct mp_osd_res *dim)
     mp_ass_set_style(&style, 288, opts->sub_text_style);
     ass_set_selective_style_override(priv, &style);
     free(style.FontName);
-    if (ctx->is_converted && track->default_style < track->n_styles) {
+    if (converted && track->default_style < track->n_styles) {
         mp_ass_set_style(track->styles + track->default_style,
                          track->PlayResY, opts->sub_text_style);
     }
@@ -217,6 +224,9 @@ static void get_bitmaps(struct sd *sd, struct mp_osd_res dim, double pts,
 {
     struct sd_ass_priv *ctx = sd->priv;
     struct MPOpts *opts = sd->opts;
+    bool no_ass = !opts->ass_enabled;
+    bool converted = ctx->is_converted || no_ass;
+    ASS_Track *track = no_ass ? ctx->shadow_track : ctx->ass_track;
 
     if (pts == MP_NOPTS_VALUE || !sd->ass_renderer)
         return;
@@ -225,8 +235,8 @@ static void get_bitmaps(struct sd *sd, struct mp_osd_res dim, double pts,
 
     ASS_Renderer *renderer = sd->ass_renderer;
     double scale = dim.display_par;
-    if (!ctx->is_converted && (!opts->ass_style_override ||
-                               opts->ass_vsfilter_aspect_compat))
+    if (!converted && (!opts->ass_style_override ||
+                       opts->ass_vsfilter_aspect_compat))
     {
         // Let's use the original video PAR for vsfilter compatibility:
         double par = scale
@@ -235,20 +245,21 @@ static void get_bitmaps(struct sd *sd, struct mp_osd_res dim, double pts,
         if (isnormal(par))
             scale = par;
     }
-    configure_ass(sd, &dim);
+    configure_ass(sd, &dim, converted, track);
     ass_set_pixel_aspect(renderer, scale);
-    if (!ctx->is_converted && (!opts->ass_style_override ||
-                               opts->ass_vsfilter_blur_compat))
+    if (!converted && (!opts->ass_style_override ||
+                       opts->ass_vsfilter_blur_compat))
     {
         ass_set_storage_size(renderer, ctx->video_params.w, ctx->video_params.h);
     } else {
         ass_set_storage_size(renderer, 0, 0);
     }
-    mp_ass_render_frame(renderer, ctx->ass_track, pts * 1000 + .5,
-                        &ctx->parts, res);
+    if (no_ass)
+        fill_plaintext(sd, pts);
+    mp_ass_render_frame(renderer, track, pts * 1000 + .5, &ctx->parts, res);
     talloc_steal(ctx, ctx->parts);
 
-    if (!ctx->is_converted)
+    if (!converted)
         mangle_colors(sd, res);
 
     pthread_mutex_unlock(sd->ass_lock);
@@ -360,6 +371,42 @@ static char *get_text(struct sd *sd, double pts)
     return ctx->last_text;
 }
 
+static void fill_plaintext(struct sd *sd, double pts)
+{
+    struct sd_ass_priv *ctx = sd->priv;
+    ASS_Track *track = ctx->shadow_track;
+
+    ass_flush_events(track);
+
+    char *text = get_text(sd, pts);
+    if (!text)
+        return;
+
+    bstr dst = {0};
+    while (*text) {
+        if (*text == '{')
+            bstr_xappend(NULL, &dst, bstr0("\\"));
+        bstr_xappend(NULL, &dst, (bstr){text, 1});
+        // Break ASS escapes with U+2060 WORD JOINER
+        if (*text == '\\')
+            mp_append_utf8_bstr(NULL, &dst, 0x2060);
+        text++;
+    }
+
+    if (!dst.start || !dst.start[0])
+        return;
+
+    int n = ass_alloc_event(track);
+    ASS_Event *event = track->events + n;
+    event->Start = 0;
+    event->Duration = INT_MAX;
+    event->Style = track->default_style;
+    event->Text = strdup(dst.start);
+
+    if (track->default_style < track->n_styles)
+        track->styles[track->default_style].Alignment = ctx->on_top ? 6 : 2;
+}
+
 static void fix_events(struct sd *sd)
 {
     struct sd_ass_priv *ctx = sd->priv;
@@ -395,10 +442,13 @@ static int control(struct sd *sd, enum sd_ctrl cmd, void *arg)
             return false;
         a[0] = res / 1000.0;
         return true;
+    }
     case SD_CTRL_SET_VIDEO_PARAMS:
         ctx->video_params = *(struct mp_image_params *)arg;
         return CONTROL_OK;
-    }
+    case SD_CTRL_SET_TOP:
+        ctx->on_top = *(bool *)arg;
+        return CONTROL_OK;
     default:
         return CONTROL_UNKNOWN;
     }