command: add property returning detected audio device

This can be useful to adjust some other audio related properties
at runtime depending on the audio device being used.

DOCS/man/input.rst

@@ -1589,6 +1589,10 @@ Property list
 ``current-ao``
     Current audio output driver (name as used with ``--ao``).
 
+``audio-out-detected-device``
+    Return the audio device selected by the AO driver (only implemented for
+    some drivers: currently only ``coreaudio``).
+
 ``mpv-version``
     Return the mpv version/copyright string. Depending on how the binary was
     built, it might contain either a release version, or just a git hash.

audio/out/ao.c

@@ -440,6 +440,11 @@ bool ao_untimed(struct ao *ao)
     return ao->untimed;
 }
 
+const char *ao_get_detected_device(struct ao *ao)
+{
+    return ao->detected_device;
+}
+
 struct ao_device_list *ao_get_device_list(struct mpv_global *global)
 {
     struct ao_device_list *list = talloc_zero(NULL, struct ao_device_list);

audio/out/ao.h

@@ -79,6 +79,7 @@ void ao_uninit(struct ao *ao);
 void ao_get_format(struct ao *ao, struct mp_audio *format);
 const char *ao_get_name(struct ao *ao);
 const char *ao_get_description(struct ao *ao);
+const char *ao_get_detected_device(struct ao *ao);
 bool ao_untimed(struct ao *ao);
 int ao_play(struct ao *ao, void **data, int samples, int flags);
 int ao_control(struct ao *ao, enum aocontrol cmd, void *arg);

audio/out/ao_coreaudio.c

@@ -156,6 +156,8 @@ static int init(struct ao *ao)
     OSStatus err = ca_select_device(ao, ao->device, &p->device);
     CHECK_CA_ERROR("failed to select device");
 
+    ao->detected_device = talloc_asprintf(ao, "%d", p->device);
+
     if (!init_chmap(ao))
         goto coreaudio_error;
 

audio/out/internal.h

@@ -50,6 +50,9 @@ struct ao {
     // default device should be used, this is set to NULL.
     char *device;
 
+    // Device actually chosen by the AO
+    char *detected_device;
+
     // Application name to report to the audio API.
     char *client_name;
 

player/command.c

@@ -1577,6 +1577,15 @@ static int mp_property_ao(void *ctx, struct m_property *p, int action, void *arg
                                     mpctx->ao ? ao_get_name(mpctx->ao) : NULL);
 }
 
+static int mp_property_ao_detected_device(void *ctx,struct m_property *prop,
+                                          int action, void *arg)
+{
+    MPContext *mpctx = ctx;
+    if (!mpctx->ao)
+        return M_PROPERTY_UNAVAILABLE;
+    return m_property_strdup_ro(action, arg, ao_get_detected_device(mpctx->ao));
+}
+
 /// Audio delay (RW)
 static int mp_property_audio_delay(void *ctx, struct m_property *prop,
                                    int action, void *arg)
@@ -3375,6 +3384,7 @@ static const struct m_property mp_properties[] = {
     {"audio-device", mp_property_audio_device},
     {"audio-device-list", mp_property_audio_devices},
     {"current-ao", mp_property_ao},
+    {"audio-out-detected-device", mp_property_ao_detected_device},
 
     // Video
     {"fullscreen", mp_property_fullscreen},
@@ -3516,7 +3526,7 @@ static const char *const *const mp_event_property_change[] = {
       "detected-hwdec"),
     E(MPV_EVENT_AUDIO_RECONFIG, "audio-format", "audio-codec", "audio-bitrate",
       "samplerate", "channels", "audio", "volume", "mute", "balance",
-      "volume-restore-data", "current-ao"),
+      "volume-restore-data", "current-ao", "audio-out-detected-device"),
     E(MPV_EVENT_SEEK, "seeking", "core-idle"),
     E(MPV_EVENT_PLAYBACK_RESTART, "seeking", "core-idle"),
     E(MPV_EVENT_METADATA_UPDATE, "metadata", "filtered-metadata"),