player: filter tags, add --display-tags option

This attempts to increase user-friendliness by excluding useless tags.
It should be especially helpful with mp4 files, because the FFmpeg mp4
demuxer adds tons of completely useless information to the metadata.

Fixes #1403.

DOCS/man/options.rst

@@ -3187,6 +3187,14 @@ PVR
 Miscellaneous
 -------------
 
+``--display-tags=tag1,tags2,...``
+    Set the list of tags that should be displayed on the terminal. Tags that
+    are in the list, but are not present in the played file, will not be shown.
+    The special value ``all`` disables filtering.
+
+    The default includes a common list of tags, call mpv with ``--list-options``
+    to see it.
+
 ``--mc=<seconds/frame>``
     Maximum A-V sync correction per frame (in seconds)
 

common/tags.c

@@ -74,6 +74,25 @@ struct mp_tags *mp_tags_dup(void *tparent, struct mp_tags *tags)
     return new;
 }
 
+// Return a copy of the tags, but containing only keys in list. Also forces
+// the order and casing of the keys (for cosmetic reasons).
+// The special key "all" matches all keys.
+struct mp_tags *mp_tags_filtered(void *tparent, struct mp_tags *tags, char **list)
+{
+    struct mp_tags *new = talloc_zero(tparent, struct mp_tags);
+    for (int n = 0; list && list[n]; n++) {
+        char *key = list[n];
+        if (strcasecmp(key, "all") == 0) {
+            talloc_free(new);
+            return mp_tags_dup(tparent, tags);
+        }
+        char *value = mp_tags_get_str(tags, key);
+        if (value)
+            mp_tags_set_str(new, key, value);
+    }
+    return new;
+}
+
 void mp_tags_merge(struct mp_tags *tags, struct mp_tags *src)
 {
     for (int n = 0; n < src->num_keys; n++)

common/tags.h

@@ -15,6 +15,7 @@ char *mp_tags_get_str(struct mp_tags *tags, const char *key);
 char *mp_tags_get_bstr(struct mp_tags *tags, bstr key);
 void mp_tags_clear(struct mp_tags *tags);
 struct mp_tags *mp_tags_dup(void *tparent, struct mp_tags *tags);
+struct mp_tags *mp_tags_filtered(void *tparent, struct mp_tags *tags, char **list);
 void mp_tags_merge(struct mp_tags *tags, struct mp_tags *src);
 struct AVDictionary;
 void mp_tags_copy_from_av_dictionary(struct mp_tags *tags,

options/options.c

@@ -213,6 +213,8 @@ const m_option_t mp_opts[] = {
     OPT_CHOICE("hls-bitrate", hls_bitrate, M_OPT_FIXED,
                ({"no", 0}, {"min", 1}, {"max", 2})),
 
+    OPT_STRINGLIST("display-tags*", display_tags, 0),
+
 #if HAVE_CDDA
     OPT_SUBSTRUCT("cdda", stream_cdda_opts, stream_cdda_conf, 0),
     OPT_STRING("cdrom-device", cdrom_device, M_OPT_FILE),
@@ -778,6 +780,12 @@ const struct MPOpts mp_default_opts = {
     .dvd_angle = 1,
 
     .mf_fps = 1.0,
+
+    .display_tags = (char **)(const char*[]){
+        "artist", "album", "album_artist", "comment", "composer", "genre",
+        "performer", "title", "track", "icy-title",
+        NULL
+    },
 };
 
 #endif /* MPLAYER_CFG_MPLAYER_H */

options/options.h

@@ -180,6 +180,7 @@ typedef struct MPOpts {
     char **audio_lang;
     char **sub_lang;
     int audio_display;
+    char **display_tags;
     int sub_visibility;
     int sub_pos;
     float sub_delay;

player/core.h

@@ -196,7 +196,7 @@ typedef struct MPContext {
     double video_offset;
 
     struct demuxer *demuxer;
-    struct mp_tags *tags;
+    struct mp_tags *filtered_tags;
 
     struct track **tracks;
     int num_tracks;

player/loadfile.c

@@ -168,9 +168,10 @@ void update_demuxer_properties(struct MPContext *mpctx)
         tracks->events &= ~DEMUX_EVENT_STREAMS;
     }
     if (events & DEMUX_EVENT_METADATA) {
-        struct mp_tags *info = demuxer->metadata;
+        struct mp_tags *info =
+            mp_tags_filtered(mpctx, demuxer->metadata, mpctx->opts->display_tags);
         // prev is used to attempt to print changed tags only (to some degree)
-        struct mp_tags *prev = mpctx->tags;
+        struct mp_tags *prev = mpctx->filtered_tags;
         int n_prev = 0;
         bool had_output = false;
         for (int n = 0; n < info->num_keys; n++) {
@@ -186,8 +187,8 @@ void update_demuxer_properties(struct MPContext *mpctx)
             MP_INFO(mpctx, " %s: %s\n", info->keys[n], info->values[n]);
             had_output = true;
         }
-        talloc_free(mpctx->tags);
-        mpctx->tags = mp_tags_dup(mpctx, info);
+        talloc_free(mpctx->filtered_tags);
+        mpctx->filtered_tags = info;
         mp_notify(mpctx, MPV_EVENT_METADATA_UPDATE, NULL);
     }
     demuxer->events = 0;
@@ -1223,8 +1224,8 @@ terminate_playback:
 
     m_config_restore_backups(mpctx->mconfig);
 
-    talloc_free(mpctx->tags);
-    mpctx->tags = NULL;
+    talloc_free(mpctx->filtered_tags);
+    mpctx->filtered_tags = NULL;
 
     mpctx->playback_initialized = false;