af_lavfi: implement af-metadata property

Works like vf-metadata. Unfortunately requires some code duplication
(even though it's not much).

Fixes #2311.

DOCS/interface-changes.rst

@@ -19,6 +19,8 @@ Interface changes
 
 ::
 
+ --- mpv 0.11.0 ---
+    - add "af-metadata" property
  --- mpv 0.10.0 ---
     - add --video-aspect-method option
     - add --playlist-pos option

DOCS/man/input.rst

@@ -1091,6 +1091,9 @@ Property list
     An example of these kind of metadata are the cropping parameters
     added by ``--vf=lavfi=cropdetect``.
 
+``af-metadata/<filter-label>``
+    Equivalent to ``vf-metadata/<filter-label>``, but for audio filters.
+
 ``pause`` (RW)
     Pause status. This is usually ``yes`` or ``no``. See ``--pause``.
 

audio/filter/af.c

@@ -695,6 +695,18 @@ void af_control_all(struct af_stream *s, int cmd, void *arg)
         af->control(af, cmd, arg);
 }
 
+int af_control_by_label(struct af_stream *s, int cmd, void *arg, bstr label)
+{
+    char *label_str = bstrdup0(NULL, label);
+    struct af_instance *cur = af_find_by_label(s, label_str);
+    talloc_free(label_str);
+    if (cur) {
+        return cur->control ? cur->control(cur, cmd, arg) : CONTROL_NA;
+    } else {
+        return CONTROL_UNKNOWN;
+    }
+}
+
 // Used by filters to add a filtered frame to the output queue.
 // Ownership of frame is transferred from caller to the filter chain.
 void af_add_output_frame(struct af_instance *af, struct mp_audio *frame)

audio/filter/af.h

@@ -127,6 +127,7 @@ enum af_control {
     AF_CONTROL_GET_PAN_BALANCE,
     AF_CONTROL_SET_PLAYBACK_SPEED,
     AF_CONTROL_SET_PLAYBACK_SPEED_RESAMPLE,
+    AF_CONTROL_GET_METADATA,
 };
 
 // Argument for AF_CONTROL_SET_PAN_LEVEL
@@ -145,6 +146,7 @@ int af_remove_by_label(struct af_stream *s, char *label);
 struct af_instance *af_find_by_label(struct af_stream *s, char *label);
 struct af_instance *af_control_any_rev(struct af_stream *s, int cmd, void *arg);
 void af_control_all(struct af_stream *s, int cmd, void *arg);
+int af_control_by_label(struct af_stream *s, int cmd, void *arg, bstr label);
 void af_seek_reset(struct af_stream *s);
 
 void af_add_output_frame(struct af_instance *af, struct mp_audio *frame);

audio/filter/af_lavfi.c

@@ -34,11 +34,14 @@
 #include <libavfilter/buffersink.h>
 #include <libavfilter/buffersrc.h>
 
+#include "config.h"
+
 #include "audio/format.h"
 #include "audio/fmt-conversion.h"
 #include "af.h"
 
 #include "common/av_common.h"
+#include "common/tags.h"
 
 #include "options/m_option.h"
 
@@ -63,6 +66,8 @@ struct priv {
 
     bool eof;
 
+    struct mp_tags *metadata;
+
     // options
     char *cfg_graph;
     char **cfg_avopts;
@@ -213,6 +218,12 @@ static int control(struct af_instance *af, int cmd, void *arg)
 
         return mp_audio_config_equals(in, &orig_in) ? AF_OK : AF_FALSE;
     }
+    case AF_CONTROL_GET_METADATA:
+        if (p->metadata) {
+            *(struct mp_tags *)arg = *p->metadata;
+            return CONTROL_OK;
+        }
+        return CONTROL_NA;
     case AF_CONTROL_RESET:
         reset(af);
         return AF_OK;
@@ -220,6 +231,17 @@ static int control(struct af_instance *af, int cmd, void *arg)
     return AF_UNKNOWN;
 }
 
+static void get_metadata_from_av_frame(struct af_instance *af, AVFrame *frame)
+{
+#if HAVE_AVFRAME_METADATA
+    struct priv *p = af->priv;
+    if (!p->metadata)
+        p->metadata = talloc_zero(p, struct mp_tags);
+
+    mp_tags_copy_from_av_dictionary(p->metadata, av_frame_get_metadata(frame));
+#endif
+}
+
 static int filter_frame(struct af_instance *af, struct mp_audio *data)
 {
     struct priv *p = af->priv;
@@ -307,6 +329,7 @@ static int filter_out(struct af_instance *af)
         af->delay = in_time - out_time;
     }
 
+    get_metadata_from_av_frame(af, frame);
     af_add_output_frame(af, out);
     av_frame_free(&frame);
     return 0;

player/command.c

@@ -1187,21 +1187,31 @@ static int mp_property_chapter_metadata(void *ctx, struct m_property *prop,
     return tag_property(action, arg, mpctx->chapters[chapter].metadata);
 }
 
-static int mp_property_vf_metadata(void *ctx, struct m_property *prop,
-                                   int action, void *arg)
+static int mp_property_filter_metadata(void *ctx, struct m_property *prop,
+                                       int action, void *arg)
 {
     MPContext *mpctx = ctx;
-    if (!(mpctx->d_video && mpctx->d_video->vfilter))
-        return M_PROPERTY_UNAVAILABLE;
-    struct vf_chain *vf = mpctx->d_video->vfilter;
+    const char *type = prop->priv;
 
     if (action == M_PROPERTY_KEY_ACTION) {
         struct m_property_action_arg *ka = arg;
         bstr key;
         char *rem;
         m_property_split_path(ka->key, &key, &rem);
-        struct mp_tags vf_metadata = {0};
-        switch (vf_control_by_label(vf, VFCTRL_GET_METADATA, &vf_metadata, key)) {
+        struct mp_tags metadata = {0};
+        int res = CONTROL_UNKNOWN;
+        if (strcmp(type, "vf") == 0) {
+            if (!(mpctx->d_video && mpctx->d_video->vfilter))
+                return M_PROPERTY_UNAVAILABLE;
+            struct vf_chain *vf = mpctx->d_video->vfilter;
+            res = vf_control_by_label(vf, VFCTRL_GET_METADATA, &metadata, key);
+        } else if (strcmp(type, "af") == 0) {
+            if (!(mpctx->d_audio && mpctx->d_audio->afilter))
+                return M_PROPERTY_UNAVAILABLE;
+            struct af_stream *af = mpctx->d_audio->afilter;
+            res = af_control_by_label(af, AF_CONTROL_GET_METADATA, &metadata, key);
+        }
+        switch (res) {
         case CONTROL_UNKNOWN:
             return M_PROPERTY_UNKNOWN;
         case CONTROL_NA: // empty
@@ -1209,9 +1219,9 @@ static int mp_property_vf_metadata(void *ctx, struct m_property *prop,
             if (strlen(rem)) {
                 struct m_property_action_arg next_ka = *ka;
                 next_ka.key = rem;
-                return tag_property(M_PROPERTY_KEY_ACTION, &next_ka, &vf_metadata);
+                return tag_property(M_PROPERTY_KEY_ACTION, &next_ka, &metadata);
             } else {
-                return tag_property(ka->action, ka->arg, &vf_metadata);
+                return tag_property(ka->action, ka->arg, &metadata);
             }
             return M_PROPERTY_OK;
         default:
@@ -3379,7 +3389,8 @@ static const struct m_property mp_properties[] = {
     {"metadata", mp_property_metadata},
     {"filtered-metadata", mp_property_filtered_metadata},
     {"chapter-metadata", mp_property_chapter_metadata},
-    {"vf-metadata", mp_property_vf_metadata},
+    {"vf-metadata", mp_property_filter_metadata, .priv = "vf"},
+    {"af-metadata", mp_property_filter_metadata, .priv = "af"},
     {"pause", mp_property_pause},
     {"core-idle", mp_property_core_idle},
     {"eof-reached", mp_property_eof_reached},