audio: support for enumerating devices of current aoout (fixes #10720)

include/vlc/libvlc_media_player.h

@@ -1473,6 +1473,27 @@ char *libvlc_audio_output_device_longname( libvlc_instance_t *, const char *,
 LIBVLC_DEPRECATED LIBVLC_API
 char *libvlc_audio_output_device_id( libvlc_instance_t *, const char *, int );
 
+/**
+ * Gets a list of potential audio output devices,
+ * \see libvlc_audio_output_device_set().
+ *
+ * \note Not all audio outputs support enumerating devices.
+ * The audio output may be functional even if the list is empty (NULL).
+ *
+ * \note The list may not be exhaustive.
+ *
+ * \warning Some audio output devices in the list might not actually work in
+ * some circumstances. By default, it is recommended to not specify any
+ * explicit audio device.
+ *
+ * \param mp media player
+ * \return A NULL-terminated linked list of potential audio output devices.
+ * It must be freed it with libvlc_audio_output_device_list_release()
+ * \version LibVLC 2.2.0 or later.
+ */
+LIBVLC_API libvlc_audio_output_device_t *
+libvlc_audio_output_device_enum( libvlc_media_player_t *mp );
+
 /**
  * Gets a list of audio output devices for a given audio output module,
  * \see libvlc_audio_output_device_set().
@@ -1514,6 +1535,9 @@ LIBVLC_API void libvlc_audio_output_device_list_release(
  * specified by the device identifier string immediately. This is the
  * recommended usage.
  *
+ * A list of adequate potential device strings can be obtained with
+ * libvlc_audio_output_device_enum().
+ *
  * However passing NULL is supported in LibVLC version 2.2.0 and later only;
  * in earlier versions, this function would have no effects when the module
  * parameter was NULL.

lib/audio.c

@@ -139,6 +139,42 @@ int libvlc_audio_output_set( libvlc_media_player_t *mp, const char *psz_name )
     return 0;
 }
 
+libvlc_audio_output_device_t *
+libvlc_audio_output_device_enum( libvlc_media_player_t *mp )
+{
+    audio_output_t *aout = GetAOut( mp );
+    if( aout == NULL )
+        return NULL;
+
+    libvlc_audio_output_device_t *list = NULL, **pp = &list;
+    char **values, **texts;
+
+    int n = aout_DevicesList( aout, &values, &texts );
+    if( n < 0 )
+        goto err;
+
+    for (int i = 0; i < n; i++)
+    {
+        libvlc_audio_output_device_t *item = malloc( sizeof(*item) );
+        if( unlikely(item == NULL) )
+        {
+            free( texts[i] );
+            free( values[i] );
+            continue;
+        }
+
+        *pp = item;
+        pp = &item->p_next;
+        item->psz_device = values[i];
+        item->psz_description = texts[i];
+    }
+
+    free( texts );
+    free( values );
+err:
+    return list;
+}
+
 libvlc_audio_output_device_t *
 libvlc_audio_output_device_list_get( libvlc_instance_t *p_instance,
                                      const char *aout )

lib/libvlc.sym

@@ -15,6 +15,7 @@ libvlc_audio_equalizer_release
 libvlc_audio_equalizer_set_amp_at_index
 libvlc_audio_equalizer_set_preamp
 libvlc_audio_output_device_count
+libvlc_audio_output_device_enum
 libvlc_audio_output_device_id
 libvlc_audio_output_device_list_get
 libvlc_audio_output_device_list_release