sub: add sub-lines property

Return all subtitle lines in memory with text, start and end.

I did not name this sub-all so it cannot be misinterpreted as referring
to all subtitle tracks.

Closes #12810.

DOCS/interface-changes/sub-lines.txt

@@ -0,0 +1 @@
+add `sub-lines` and `secondary-sub-lines` properties

DOCS/man/input.rst

@@ -3290,6 +3290,29 @@ Property list
 ``secondary-sub-end``
     Same as ``sub-end``, but for the secondary subtitles.
 
+``sub-lines``
+    The list of subtitle lines in memory. Not available if the subtitle is not
+    text-based (i.e. DVD/BD subtitles).
+
+    When querying the property with the client API using ``MPV_FORMAT_NODE``,
+    or with Lua ``mp.get_property_native``, this will return a mpv_node with
+    the following contents:
+
+    ::
+
+        MPV_FORMAT_NODE_ARRAY
+            MPV_FORMAT_NODE_MAP (for each subtitle line)
+                "text"  MPV_FORMAT_STRING
+                "start" MPV_FORMAT_DOUBLE
+                "end"   MPV_FORMAT_DOUBLE
+
+    ASS tags are stripped from ``text``.
+
+    ``end`` is absent if unknown.
+
+``secondary-sub-lines``
+    Same as ``sub-lines``, but for the secondary subtitles.
+
 ``playlist-pos`` (RW)
     Current position on playlist. The first entry is on position 0. Writing to
     this property may start playback at the new position.

player/command.c

@@ -3455,6 +3455,43 @@ static int mp_property_sub_end(void *ctx, struct m_property *prop,
     return property_time(action, arg, end);
 }
 
+static int mp_property_sub_lines(void *ctx, struct m_property *prop,
+                                 int action, void *arg)
+{
+    MPContext *mpctx = ctx;
+    int sub_index = *(int *)prop->priv;
+    struct track *track = mpctx->current_track[sub_index][STREAM_SUB];
+    struct dec_sub *sub = track ? track->d_sub : NULL;
+    if (!sub)
+        return M_PROPERTY_UNAVAILABLE;
+
+    switch (action) {
+    case M_PROPERTY_GET_TYPE:
+        *(struct m_option *)arg = (struct m_option){.type = CONF_TYPE_NODE};
+        return M_PROPERTY_OK;
+    case M_PROPERTY_GET:
+    case M_PROPERTY_GET_NODE: {
+        struct sub_lines *lines = sub_get_lines(sub);
+        if (!lines)
+            return M_PROPERTY_UNAVAILABLE;
+
+        struct mpv_node *node = arg;
+        node_init(node, MPV_FORMAT_NODE_ARRAY, NULL);
+        for (int i = 0; i < lines->num_entries; i++) {
+            struct sub_line *line = &lines->entries[i];
+            struct mpv_node *entry = node_array_add(node, MPV_FORMAT_NODE_MAP);
+            node_map_add_string(entry, "text", line->text);
+            node_map_add_double(entry, "start", line->start);
+            if (line->end != MP_NOPTS_VALUE)
+                node_map_add_double(entry, "end", line->end);
+        }
+        talloc_free(lines);
+        return M_PROPERTY_OK;
+    }
+    }
+    return M_PROPERTY_NOT_IMPLEMENTED;
+}
+
 static int mp_property_playlist_current_pos(void *ctx, struct m_property *prop,
                                             int action, void *arg)
 {
@@ -4650,6 +4687,10 @@ static const struct m_property mp_properties_base[] = {
         .priv = (void *)&(const int){0}},
     {"secondary-sub-end", mp_property_sub_end,
         .priv = (void *)&(const int){1}},
+    {"sub-lines", mp_property_sub_lines,
+        .priv = (void *)&(const int){0}},
+    {"secondary-sub-lines", mp_property_sub_lines,
+        .priv = (void *)&(const int){1}},
 
     {"vf", mp_property_vf},
     {"af", mp_property_af},
@@ -4734,8 +4775,8 @@ static const char *const *const mp_event_property_change[] = {
       "secondary-sub-text", "audio-bitrate", "video-bitrate", "sub-bitrate",
       "decoder-frame-drop-count", "frame-drop-count", "video-frame-info",
       "vf-metadata", "af-metadata", "sub-start", "sub-end", "secondary-sub-start",
-      "secondary-sub-end", "video-out-params", "video-dec-params", "video-params",
-      "deinterlace-active", "video-target-params"),
+      "secondary-sub-end", "sub-lines", "secondary-sub-lines", "video-out-params",
+      "video-dec-params", "video-params", "deinterlace-active", "video-target-params"),
     E(MP_EVENT_DURATION_UPDATE, "duration"),
     E(MPV_EVENT_VIDEO_RECONFIG, "video-out-params", "video-params",
       "video-format", "video-codec", "video-bitrate", "dwidth", "dheight",

sub/dec_sub.c

@@ -580,3 +580,24 @@ bool sub_is_secondary_visible(struct dec_sub *sub)
     mp_mutex_unlock(&sub->lock);
     return ret;
 }
+
+static int sub_line_cmp(const void *a, const void *b)
+{
+    const struct sub_line *la = a, *lb = b;
+    if (la->start < lb->start) return -1;
+    if (la->start > lb->start) return  1;
+    return 0;
+}
+
+struct sub_lines *sub_get_lines(struct dec_sub *sub)
+{
+    mp_mutex_lock(&sub->lock);
+    struct sub_lines *res = NULL;
+    if (sub->sd->driver->get_lines) {
+        res = sub->sd->driver->get_lines(sub->sd);
+        qsort(res->entries, res->num_entries, sizeof(res->entries[0]),
+              sub_line_cmp);
+    }
+    mp_mutex_unlock(&sub->lock);
+    return res;
+}

sub/dec_sub.h

@@ -39,6 +39,17 @@ struct attachment_list {
     int num_entries;
 };
 
+struct sub_line {
+    char *text;
+    double start;
+    double end;
+};
+
+struct sub_lines {
+    struct sub_line *entries;
+    int num_entries;
+};
+
 struct dec_sub *sub_create(struct mpv_global *global, struct track *track,
                            struct attachment_list *attachments, int order);
 void sub_destroy(struct dec_sub *sub);
@@ -53,6 +64,9 @@ struct sub_bitmaps *sub_get_bitmaps(struct dec_sub *sub, struct mp_osd_res dim,
 char *sub_get_text(struct dec_sub *sub, double pts, enum sd_text_type type);
 char *sub_ass_get_extradata(struct dec_sub *sub);
 struct sd_times sub_get_times(struct dec_sub *sub, double pts);
+// Return subtitle lines in memory. Call talloc_free() on the return value.
+struct sub_lines *sub_get_lines(struct dec_sub *sub);
+
 void sub_reset(struct dec_sub *sub);
 void sub_select(struct dec_sub *sub, bool selected);
 void sub_set_recorder_sink(struct dec_sub *sub, struct mp_recorder_sink *sink);

sub/sd.h

@@ -52,6 +52,7 @@ struct sd_functions {
                                        int format, double pts);
     char *(*get_text)(struct sd *sd, double pts, enum sd_text_type type);
     struct sd_times (*get_times)(struct sd *sd, double pts);
+    struct sub_lines *(*get_lines)(struct sd *sd);
 };
 
 // lavc_conv.c

sub/sd_ass.c

@@ -1017,6 +1017,44 @@ static void uninit(struct sd *sd)
     talloc_free(ctx->copy_cache);
 }
 
+static struct sub_lines *get_lines(struct sd *sd)
+{
+    struct sd_ass_priv *ctx = sd->priv;
+    ASS_Track *track = ctx->ass_track;
+    struct sub_lines *res = talloc_zero(NULL, struct sub_lines);
+
+    for (int i = 0; i < track->n_events; i++) {
+        ASS_Event *event = &track->events[i];
+        if (!event->Text)
+            continue;
+
+        char *plain = NULL;
+        bstr result = sd_ass_to_plaintext(&plain, event->Text);
+
+        // ASS subtitle lines can have many empty lines after stripping tags,
+        // but empty lines are useful in LRC.
+        if (is_whitespace_only(result)) {
+            talloc_free(plain);
+            if (!strcmp(sd->codec->codec, "ass"))
+                continue;
+            plain = talloc_strdup(res, "");
+        } else {
+            talloc_steal(res, plain);
+        }
+
+        struct sub_line line = {
+            .text  = plain,
+            .start = event->Start / 1000.0,
+            .end   = event->Duration == UNKNOWN_DURATION * 1000
+                         ? MP_NOPTS_VALUE
+                         : (event->Start + event->Duration) / 1000.0,
+        };
+        MP_TARRAY_APPEND(res, res->entries, res->num_entries, line);
+    }
+
+    return res;
+}
+
 static int control(struct sd *sd, enum sd_ctrl cmd, void *arg)
 {
     struct sd_ass_priv *ctx = sd->priv;
@@ -1072,6 +1110,7 @@ const struct sd_functions sd_ass = {
     .get_bitmaps = get_bitmaps,
     .get_text = get_text,
     .get_times = get_times,
+    .get_lines = get_lines,
     .control = control,
     .reset = reset,
     .select = enable_output,