audio: pipewire: Report default devices first

Further refactor the device enumeration code to retrieve the default sink/source node IDs from the metadata node.  Use the retrieved IDs to sort the device list so that the default devices are at the beginning and thus are the first reported to SDL.

src/audio/pipewire/SDL_pipewire.c

@@ -24,12 +24,13 @@
 
 #if SDL_AUDIO_DRIVER_PIPEWIRE
 
-#include <spa/param/audio/format-utils.h>
-
 #include "SDL_audio.h"
 #include "SDL_loadso.h"
 #include "SDL_pipewire.h"
 
+#include <pipewire/extensions/metadata.h>
+#include <spa/param/audio/format-utils.h>
+
 /*
  * These seem to be sane limits as Pipewire
  * uses them in several of it's own modules.
@@ -187,28 +188,29 @@ deinit_pipewire_library()
   unload_pipewire_library();
 }
 
-/* Linked lists for tracking pending and connected devices */
-struct connected_device
+/* Linked lists for tracking nodes and connected devices */
+struct node_object
 {
   struct spa_list link;
 
-  Uint32        id;
-  SDL_bool      is_capture;
-  SDL_AudioSpec spec;
+  Uint32 id;
+  int    seq;
+  void * userdata;
 
-  char name[];
+  struct pw_proxy *proxy;
+  struct spa_hook  node_listener;
+  struct spa_hook  core_listener;
 };
 
-struct node_object
+struct connected_device
 {
   struct spa_list link;
 
-  struct pw_proxy *proxy;
-  struct spa_hook  node_listener;
-  struct spa_hook  core_listener;
-  int              seq;
+  Uint32        id;
+  SDL_bool      is_capture;
+  SDL_AudioSpec spec;
 
-  struct connected_device *dev;
+  char name[];
 };
 
 /* The global hotplug thread and associated objects. */
@@ -224,17 +226,22 @@ static int                    hotplug_init_seq_val;
 static SDL_atomic_t           hotplug_init_complete;
 static SDL_atomic_t           hotplug_events_enabled;
 
+Uint32 pipewire_default_sink_id   = SPA_ID_INVALID;
+Uint32 pipewire_default_source_id = SPA_ID_INVALID;
+
 /* The active device list */
-static void
+static SDL_bool
 check_add_device(struct connected_device *new_dev)
 {
   struct connected_device *dev;
+  SDL_bool                 ret = SDL_TRUE;
 
   PIPEWIRE_pw_thread_loop_lock(hotplug_loop);
 
   /* See if the device is already in the list */
   spa_list_for_each (dev, &hotplug_device_list, link) {
     if (dev->id == new_dev->id) {
+      ret = SDL_FALSE;
       goto dup_found;
     }
   }
@@ -249,10 +256,12 @@ check_add_device(struct connected_device *new_dev)
 dup_found:
 
   PIPEWIRE_pw_thread_loop_unlock(hotplug_loop);
+
+  return ret;
 }
 
 static void
-check_remove_device(Uint32 id)
+remove_device(Uint32 id)
 {
   struct connected_device *dev, *temp;
 
@@ -276,6 +285,35 @@ check_remove_device(Uint32 id)
   PIPEWIRE_pw_thread_loop_unlock(hotplug_loop);
 }
 
+static void
+sort_devices()
+{
+  struct connected_device *dev, *temp, *default_sink, *default_source;
+
+  PIPEWIRE_pw_thread_loop_lock(hotplug_loop);
+
+  /* Find and move the default devices to the beginning of the list */
+  spa_list_for_each_safe (dev, temp, &hotplug_device_list, link) {
+    if (dev->id == pipewire_default_sink_id) {
+      default_sink = dev;
+      spa_list_remove(&dev->link);
+    } else if (dev->id == pipewire_default_source_id) {
+      default_source = dev;
+      spa_list_remove(&dev->link);
+    }
+  }
+
+  if (default_source) {
+    spa_list_prepend(&hotplug_device_list, &default_source->link);
+  }
+
+  if (default_sink) {
+    spa_list_prepend(&hotplug_device_list, &default_sink->link);
+  }
+
+  PIPEWIRE_pw_thread_loop_unlock(hotplug_loop);
+}
+
 static void
 release_device_list()
 {
@@ -287,7 +325,17 @@ release_device_list()
   }
 }
 
-/* The pending device list */
+/* The pending node list */
+static void
+destroy_node_object(struct node_object *node)
+{
+  spa_list_remove(&node->link);
+  spa_hook_remove(&node->node_listener);
+  spa_hook_remove(&node->core_listener);
+  SDL_free(node->userdata);
+  PIPEWIRE_pw_proxy_destroy(node->proxy);
+}
+
 static void
 add_pending(struct node_object *node)
 {
@@ -298,15 +346,11 @@ add_pending(struct node_object *node)
 static void
 remove_pending(Uint32 id)
 {
-  struct node_object *n, *temp;
-
-  spa_list_for_each_safe (n, temp, &hotplug_pending_list, link) {
-    if (n->dev->id == id) {
-      spa_list_remove(&n->link);
-      spa_hook_remove(&n->core_listener);
-      spa_hook_remove(&n->node_listener);
-      SDL_free(n->dev);
-      PIPEWIRE_pw_proxy_destroy(n->proxy);
+  struct node_object *node, *temp;
+
+  spa_list_for_each_safe (node, temp, &hotplug_pending_list, link) {
+    if (node->id == id) {
+      destroy_node_object(node);
     }
   }
 }
@@ -314,31 +358,40 @@ remove_pending(Uint32 id)
 static void
 release_pending_list()
 {
-  struct node_object *n, *temp;
+  struct node_object *node, *temp;
 
-  spa_list_for_each_safe (n, temp, &hotplug_pending_list, link) {
-    spa_list_remove(&n->link);
-    spa_hook_remove(&n->core_listener);
-    spa_hook_remove(&n->node_listener);
-    SDL_free(n->dev);
-    PIPEWIRE_pw_proxy_destroy(n->proxy);
+  spa_list_for_each_safe (node, temp, &hotplug_pending_list, link) {
+    destroy_node_object(node);
   }
 }
 
-static void
-pending_to_active(struct node_object *node)
+static void *
+alloc_node_object(Uint32 id, const char *type, Uint32 version, const void *funcs, const struct pw_core_events *core_events)
 {
-  SDL_assert(node);
+  struct pw_proxy *   proxy;
+  struct node_object *node;
 
-  /*
-   * Move the specified device to the active list
-   * and destroy the hooks and proxy for the node.
-   */
-  spa_list_remove(&node->link);
-  check_add_device(node->dev);
-  spa_hook_remove(&node->node_listener);
-  spa_hook_remove(&node->core_listener);
-  PIPEWIRE_pw_proxy_destroy(node->proxy);
+  /* Create the proxy object */
+  proxy = pw_registry_bind(hotplug_registry, id, type, version, sizeof(struct node_object));
+  if (proxy == NULL) {
+    SDL_SetError("Pipewire: Failed to create proxy object (%i)", errno);
+    return NULL;
+  }
+
+  node = PIPEWIRE_pw_proxy_get_user_data(proxy);
+  SDL_zerop(node);
+
+  node->id    = id;
+  node->proxy = proxy;
+
+  /* Add the callbacks */
+  pw_core_add_listener(hotplug_core, &node->core_listener, core_events, node);
+  PIPEWIRE_pw_proxy_add_object_listener(node->proxy, &node->node_listener, funcs, node);
+
+  /* Add the node to the active list */
+  add_pending(node);
+
+  return node;
 }
 
 /* Core sync points */
@@ -360,18 +413,37 @@ core_events_hotplug_init_callback(void *object, uint32_t id, int seq)
 }
 
 static void
-core_events_node_callback(void *object, uint32_t id, int seq)
+core_events_interface_callback(void *object, uint32_t id, int seq)
+{
+  struct node_object *     node = object;
+  struct connected_device *dev  = node->userdata;
+
+  if (id == PW_ID_CORE && seq == node->seq) {
+    /*
+     * Move the device to the connected list.
+     * On success, the device list owns the device object.
+     */
+    if (check_add_device(dev)) {
+      node->userdata = NULL;
+    }
+
+    destroy_node_object(node);
+  }
+}
+
+static void
+core_events_metadata_callback(void *object, uint32_t id, int seq)
 {
   struct node_object *node = object;
 
   if (id == PW_ID_CORE && seq == node->seq) {
-    /* Move the node from the pending to the active list */
-    pending_to_active(node);
+    destroy_node_object(node);
   }
 }
 
-const struct pw_core_events hotplug_core_events = { PW_VERSION_CORE_EVENTS, .done = core_events_hotplug_init_callback };
-const struct pw_core_events node_core_events    = { PW_VERSION_CORE_EVENTS, .done = core_events_node_callback };
+const struct pw_core_events hotplug_init_core_events = { PW_VERSION_CORE_EVENTS, .done = core_events_hotplug_init_callback };
+const struct pw_core_events interface_core_events    = { PW_VERSION_CORE_EVENTS, .done = core_events_interface_callback };
+const struct pw_core_events metadata_core_events     = { PW_VERSION_CORE_EVENTS, .done = core_events_metadata_callback };
 
 static void
 hotplug_core_sync(struct node_object *node)
@@ -445,23 +517,24 @@ get_int_param(const struct spa_pod *param, Uint32 key, int *val)
   return SDL_FALSE;
 }
 
-/* Detailed node information callbacks */
+/* Interface node callbacks */
 static void
 node_event_info(void *object, const struct pw_node_info *info)
 {
-  struct node_object *node = object;
-  const char *        prop_val;
-  Uint32              i;
+  struct node_object *     node = object;
+  struct connected_device *dev  = node->userdata;
+  const char *             prop_val;
+  Uint32                   i;
 
   if (info) {
     prop_val = spa_dict_lookup(info->props, PW_KEY_AUDIO_CHANNELS);
     if (prop_val) {
-      node->dev->spec.channels = (Uint8)SDL_atoi(prop_val);
+      dev->spec.channels = (Uint8)SDL_atoi(prop_val);
     }
 
     /* Need to parse the parameters to get the sample rate */
     for (i = 0; i < info->n_params; ++i) {
-      pw_node_enum_params((struct pw_node *)node->proxy, 0, info->params[i].id, 0, 0, NULL);
+      pw_node_enum_params(node->proxy, 0, info->params[i].id, 0, 0, NULL);
     }
 
     hotplug_core_sync(node);
@@ -471,42 +544,65 @@ node_event_info(void *object, const struct pw_node_info *info)
 static void
 node_event_param(void *object, int seq, uint32_t id, uint32_t index, uint32_t next, const struct spa_pod *param)
 {
-  struct node_object *node = object;
+  struct node_object *     node = object;
+  struct connected_device *dev  = node->userdata;
 
   /* Get the default frequency */
-  if (node->dev->spec.freq == 0) {
-    get_range_param(param, SPA_FORMAT_AUDIO_rate, &node->dev->spec.freq, NULL, NULL);
+  if (dev->spec.freq == 0) {
+    get_range_param(param, SPA_FORMAT_AUDIO_rate, &dev->spec.freq, NULL, NULL);
   }
 
   /*
    * The channel count should have come from the node properties,
    * but it is stored here as well. If one failed, try the other.
    */
-  if (node->dev->spec.channels == 0) {
+  if (dev->spec.channels == 0) {
     int channels;
     if (get_int_param(param, SPA_FORMAT_AUDIO_channels, &channels)) {
-      node->dev->spec.channels = (Uint8)channels;
+      dev->spec.channels = (Uint8)channels;
     }
   }
 }
 
-static const struct pw_node_events node_events = { PW_VERSION_NODE_EVENTS, .info = node_event_info, .param = node_event_param };
+static const struct pw_node_events interface_node_events = { PW_VERSION_NODE_EVENTS, .info = node_event_info,
+                                                             .param = node_event_param };
+
+/* Metadata node callback */
+static int
+metadata_property(void *object, Uint32 subject, const char *key, const char *type, const char *value)
+{
+  if (subject == PW_ID_CORE && key != NULL && value != NULL) {
+    Uint32 val = SDL_atoi(value);
+
+    if (!SDL_strcmp(key, "default.audio.sink")) {
+      pipewire_default_sink_id = val;
+    } else if (!SDL_strcmp(key, "default.audio.source")) {
+      pipewire_default_source_id = val;
+    }
+  }
+
+  return 0;
+}
+
+static const struct pw_metadata_events metadata_node_events = { PW_VERSION_METADATA_EVENTS, .property = metadata_property };
 
 /* Global registry callbacks */
 static void
 registry_event_global_callback(void *object, uint32_t id, uint32_t permissions, const char *type, uint32_t version,
                                const struct spa_dict *props)
 {
-  const char *        node_nick, *node_desc;
-  struct pw_proxy *   proxy;
   struct node_object *node;
-  SDL_bool            is_capture;
-  int                 str_buffer_len;
 
   /* We're only interested in nodes */
   if (!SDL_strcmp(type, PW_TYPE_INTERFACE_Node)) {
     const char *media_class = spa_dict_lookup(props, PW_KEY_MEDIA_CLASS);
+
     if (media_class) {
+      const char *             node_nick, *node_desc;
+      struct connected_device *dev;
+      SDL_bool                 is_capture;
+      int                      str_buffer_len;
+
       /* Just want sink and capture */
       if (!SDL_strcasecmp(media_class, "Audio/Sink")) {
         is_capture = SDL_FALSE;
@@ -520,43 +616,40 @@ registry_event_global_callback(void *object, uint32_t id, uint32_t permissions,
       node_desc = spa_dict_lookup(props, PW_KEY_NODE_DESCRIPTION);
 
       if (node_nick && node_desc) {
-        proxy = pw_registry_bind(hotplug_registry, id, type, PW_VERSION_NODE, sizeof(struct node_object));
-        if (proxy == NULL) {
+        node = alloc_node_object(id, type, version, &interface_node_events, &interface_core_events);
+        if (node == NULL) {
+          SDL_SetError("Pipewire: Failed to allocate interface node");
           return;
         }
 
-        /* The proxy object owns the node's memory and it will be freed when the proxy is destroyed */
-        node = PIPEWIRE_pw_proxy_get_user_data(proxy);
-        SDL_memset(node, 0, sizeof(struct node_object));
-
-        node->proxy = proxy;
-
         /* Allocate and initialize the device information struct */
         str_buffer_len = SDL_strlen(node_nick) + SDL_strlen(node_desc) + 3;
-        node->dev      = SDL_calloc(1, sizeof(struct connected_device) + str_buffer_len);
-        if (node->dev == NULL) {
-          PIPEWIRE_pw_proxy_destroy(proxy);
+        node->userdata = dev = SDL_calloc(1, sizeof(struct connected_device) + str_buffer_len);
+        if (dev == NULL) {
+          destroy_node_object(node);
           SDL_OutOfMemory();
           return;
         }
 
         /* Begin setting the device properties */
-        node->dev->id          = id;
-        node->dev->is_capture  = is_capture;
-        node->dev->spec.format = AUDIO_F32; /* Pipewire uses floats internally, other formats require conversion */
-        SDL_snprintf(node->dev->name, str_buffer_len, "%s: %s", node_nick, node_desc);
-
-        /* Set the callbacks */
-        pw_core_add_listener(hotplug_core, &node->core_listener, &node_core_events, node);
-        PIPEWIRE_pw_proxy_add_object_listener(node->proxy, &node->node_listener, &node_events, node);
-
-        /* Add this node to the pending list */
-        add_pending(node);
+        dev->id          = id;
+        dev->is_capture  = is_capture;
+        dev->spec.format = AUDIO_F32; /* Pipewire uses floats internally, other formats require conversion */
+        SDL_snprintf(dev->name, str_buffer_len, "%s: %s", node_nick, node_desc);
 
         /* Update sync points */
         hotplug_core_sync(node);
       }
     }
+  } else if (!SDL_strcmp(type, PW_TYPE_INTERFACE_Metadata)) {
+    node = alloc_node_object(id, type, version, &metadata_node_events, &metadata_core_events);
+    if (node == NULL) {
+      SDL_SetError("Pipewire: Failed to allocate metadata node");
+      return;
+    }
+
+    /* Update sync points */
+    hotplug_core_sync(node);
   }
 }
 
@@ -564,7 +657,7 @@ static void
 registry_event_remove_callback(void *object, uint32_t id)
 {
   remove_pending(id);
-  check_remove_device(id);
+  remove_device(id);
 }
 
 static const struct pw_registry_events registry_events = { PW_VERSION_REGISTRY_EVENTS, .global = registry_event_global_callback,
@@ -602,7 +695,7 @@ hotplug_loop_init()
   pw_registry_add_listener(hotplug_registry, &hotplug_registry_listener, &registry_events, NULL);
 
   spa_zero(hotplug_core_listener);
-  pw_core_add_listener(hotplug_core, &hotplug_core_listener, &hotplug_core_events, NULL);
+  pw_core_add_listener(hotplug_core, &hotplug_core_listener, &hotplug_init_core_events, NULL);
 
   hotplug_init_seq_val = pw_core_sync(hotplug_core, PW_ID_CORE, 0);
 
@@ -653,6 +746,9 @@ PIPEWIRE_DetectDevices()
     PIPEWIRE_pw_thread_loop_wait(hotplug_loop);
   }
 
+  /* Sort the device list so the default source/sink are listed first */
+  sort_devices();
+
   spa_list_for_each (dev, &hotplug_device_list, link) {
     SDL_AddAudioDevice(dev->is_capture, dev->name, PW_ID_TO_HANDLE(dev->id));
   }