demux: handle tag updates differently

Instead of printing lines like:

    Demuxer info GENRE changed to Alternative Rock

Just output all tags once they change. The assumption is that individual
tags rarely change, while all tags change in the common case.

This changes tag updates to use polling. This could be fixed later,
although the ICY stuff makes it a bit painful, so maybe it will remain
this way.

Also remove DEMUXER_CTRL_UPDATE_INFO. This was intended to check for tag
updates, but now we use a different approach.

3 files changed, 21 insertions, 15 deletions

diff --git a/demux/demux.c b/demux/demux.c
index fe5ac6a3d6..ceaa9db79c 100644
--- a/demux/demux.c
+++ b/demux/demux.c
@@ -720,19 +720,11 @@ int demux_info_add(demuxer_t *demuxer, const char *opt, const char *param)
 
 int demux_info_add_bstr(demuxer_t *demuxer, struct bstr opt, struct bstr param)
 {
-    char *oldval = mp_tags_get_bstr(demuxer->metadata, opt);
-    if (oldval) {
-        if (bstrcmp0(param, oldval) == 0)
-            return 0;
-        MP_INFO(demuxer, "Demuxer info %.*s changed to %.*s\n",
-                BSTR_P(opt), BSTR_P(param));
-    }
-
     mp_tags_set_bstr(demuxer->metadata, opt, param);
     return 1;
 }
 
-int demux_info_print(demuxer_t *demuxer)
+static int demux_info_print(demuxer_t *demuxer)
 {
     struct mp_tags *info = demuxer->metadata;
     int n;
@@ -760,14 +752,29 @@ char *demux_info_get(demuxer_t *demuxer, const char *opt)
 
 void demux_info_update(struct demuxer *demuxer)
 {
-    demux_control(demuxer, DEMUXER_CTRL_UPDATE_INFO, NULL);
+    struct mp_tags *tags = demuxer->metadata;
     // Take care of stream metadata as well
     char **meta;
     if (stream_control(demuxer->stream, STREAM_CTRL_GET_METADATA, &meta) > 0) {
         for (int n = 0; meta[n + 0]; n += 2)
-            demux_info_add(demuxer, meta[n + 0], meta[n + 1]);
+            mp_tags_set_str(tags, meta[n + 0], meta[n + 1]);
         talloc_free(meta);
     }
+    // Check for metadata changes the hard way.
+    char *data = talloc_strdup(demuxer, "");
+    for (int n = 0; n < tags->num_keys; n++) {
+        data = talloc_asprintf_append_buffer(data, "%s=%s\n", tags->keys[n],
+                                             tags->values[n]);
+    }
+    if (!demuxer->previous_metadata ||
+        strcmp(demuxer->previous_metadata, data) != 0)
+    {
+        talloc_free(demuxer->previous_metadata);
+        demuxer->previous_metadata = data;
+        demux_info_print(demuxer);
+    } else {
+        talloc_free(data);
+    }
 }
 
 int demux_control(demuxer_t *demuxer, int cmd, void *arg)
diff --git a/demux/demux.h b/demux/demux.h
index a979a357c1..2c8211e246 100644
--- a/demux/demux.h
+++ b/demux/demux.h
@@ -50,8 +50,7 @@ enum demuxer_type {
 #define DEMUXER_CTRL_GUESS 2
 
 enum demux_ctrl {
-    DEMUXER_CTRL_UPDATE_INFO = 1,
-    DEMUXER_CTRL_SWITCHED_TRACKS,
+    DEMUXER_CTRL_SWITCHED_TRACKS = 1,
     DEMUXER_CTRL_GET_TIME_LENGTH,
     DEMUXER_CTRL_GET_START_TIME,
     DEMUXER_CTRL_RESYNC,
@@ -199,6 +198,7 @@ typedef struct demuxer {
     struct playlist *playlist;
 
     struct mp_tags *metadata;
+    char *previous_metadata;
 
     void *priv;   // demuxer-specific internal data
     struct MPOpts *opts;
@@ -247,7 +247,6 @@ int demux_info_add(struct demuxer *demuxer, const char *opt, const char *param);
 int demux_info_add_bstr(struct demuxer *demuxer, struct bstr opt,
                         struct bstr param);
 char *demux_info_get(struct demuxer *demuxer, const char *opt);
-int demux_info_print(struct demuxer *demuxer);
 void demux_info_update(struct demuxer *demuxer);
 
 int demux_control(struct demuxer *demuxer, int cmd, void *arg);
diff --git a/player/loadfile.c b/player/loadfile.c
index 13335db886..685d87d380 100644
--- a/player/loadfile.c
+++ b/player/loadfile.c
@@ -1256,7 +1256,7 @@ goto_reopen_demuxer: ;
     }
     reselect_demux_streams(mpctx);
 
-    demux_info_print(mpctx->master_demuxer);
+    demux_info_update(mpctx->master_demuxer);
     print_file_properties(mpctx);
 
 #if HAVE_ENCODING