[dacp/player] Change support for prevent-playback and busy (ref issue #934)

Adds support for dcmp.device-busy, and also changes handling of
device-prevent-playback so it matches iTunes better.

src/dacp_prop.gperf

@@ -13,6 +13,7 @@ struct dacp_prop_map;
 "dmcp.volume",                          dacp_propget_volume,                 dacp_propset_volume
 "dmcp.device-volume",                   NULL,                                dacp_propset_devicevolume
 "dmcp.device-prevent-playback",         NULL,                                dacp_propset_devicepreventplayback
+"dmcp.device-busy",                     NULL,                                dacp_propset_devicebusy
 "dacp.playerstate",                     dacp_propget_playerstate,            NULL
 "dacp.nowplaying",                      dacp_propget_nowplaying,             NULL
 "dacp.playingtime",                     dacp_propget_playingtime,            dacp_propset_playingtime

src/httpd_dacp.c

@@ -117,6 +117,8 @@ dacp_propset_devicevolume(const char *value, struct httpd_request *hreq);
 static void
 dacp_propset_devicepreventplayback(const char *value, struct httpd_request *hreq);
 static void
+dacp_propset_devicebusy(const char *value, struct httpd_request *hreq);
+static void
 dacp_propset_playingtime(const char *value, struct httpd_request *hreq);
 static void
 dacp_propset_shufflestate(const char *value, struct httpd_request *hreq);
@@ -1011,13 +1013,8 @@ dacp_propset_devicevolume(const char *value, struct httpd_request *hreq)
   player_volume_update_speaker(speaker_info.id, value);
 }
 
-// iTunes seems to use this as way for a speaker to tell the server that it is
-// busy with something else. If the speaker makes the request with the value 1,
-// then iTunes will disable the speaker, and if it is the only speaker, then
-// playback will also be paused. It is not possible for the user to restart the
-// speaker until it has made a request with value 0 (if attempted, iTunes will
-// show it is waiting for the speaker). As you can see from the below, we
-// don't fully match this behaviour, instead we just enable/disable.
+// See player.c:speaker_prevent_playback_set() for comments regarding
+// prevent-playback and busy properties
 static void
 dacp_propset_devicepreventplayback(const char *value, struct httpd_request *hreq)
 {
@@ -1027,13 +1024,29 @@ dacp_propset_devicepreventplayback(const char *value, struct httpd_request *hreq
     return;
 
   if (value[0] == '1')
-    player_speaker_disable(speaker_info.id);
+    player_speaker_prevent_playback_set(speaker_info.id, true);
   else if (value[0] == '0')
-    player_speaker_enable(speaker_info.id);
+    player_speaker_prevent_playback_set(speaker_info.id, false);
   else
     DPRINTF(E_LOG, L_DACP, "Request for setting device-prevent-playback has invalid value: '%s'\n", value);
 }
 
+static void
+dacp_propset_devicebusy(const char *value, struct httpd_request *hreq)
+{
+  struct player_speaker_info speaker_info;
+
+  if (speaker_get(&speaker_info, hreq, "device-busy") < 0)
+    return;
+
+  if (value[0] == '1')
+    player_speaker_busy_set(speaker_info.id, true);
+  else if (value[0] == '0')
+    player_speaker_busy_set(speaker_info.id, false);
+  else
+    DPRINTF(E_LOG, L_DACP, "Request for setting device-busy has invalid value: '%s'\n", value);
+}
+
 static void
 dacp_propset_playingtime(const char *value, struct httpd_request *hreq)
 {
@@ -2516,6 +2529,7 @@ dacp_reply_setproperty(struct httpd_request *hreq)
    * dmcp.volume                      0-100, float
    * dmcp.device-volume               -144-0, float (raop volume)
    * dmcp.device-prevent-playback     0/1
+   * dmcp.device-busy                 0/1
    */
 
   /* /ctrl-int/1/setproperty?dacp.shufflestate=1&session-id=100 */

src/outputs.h

@@ -129,6 +129,8 @@ struct output_device
   unsigned has_video:1;
   unsigned requires_auth:1;
   unsigned v6_disabled:1;
+  unsigned prevent_playback:1;
+  unsigned busy:1;
 
   // Credentials if relevant
   const char *password;

src/player.c

@@ -112,12 +112,6 @@
 
 //#define DEBUG_PLAYER 1
 
-struct volume_param {
-  uint64_t spk_id;
-  int volume;
-  const char *value;
-};
-
 struct spk_enum
 {
   spk_enum_cb cb;
@@ -130,6 +124,17 @@ struct speaker_set_param
   int intval;
 };
 
+struct speaker_attr_param
+{
+  uint64_t spk_id;
+
+  int volume;
+  const char *volstr;
+
+  bool prevent_playback;
+  bool busy;
+};
+
 struct speaker_get_param
 {
   uint64_t spk_id;
@@ -376,6 +381,8 @@ static void
 speaker_select_output(struct output_device *device)
 {
   device->selected = 1;
+  device->prevent_playback = 0;
+  device->busy = 0;
 
   if (device->volume > master_volume)
     {
@@ -2402,6 +2409,8 @@ device_to_speaker_info(struct player_speaker_info *spk, struct output_device *de
   spk->has_video = device->has_video;
   spk->requires_auth = device->requires_auth;
   spk->needs_auth_key = (device->requires_auth && device->auth_key == NULL);
+  spk->prevent_playback = device->prevent_playback;
+  spk->busy = device->busy;
 }
 
 static enum command_state
@@ -2627,6 +2636,92 @@ speaker_disable(void *arg, int *retval)
   return COMMAND_END;
 }
 
+/*
+ * Airplay speakers can via DACP set the "busy" + "prevent-playback" properties,
+ * which we handle below. We try to do this like iTunes, except we need to
+ * unselect devices, since our clients don't understand the "grayed out" state:
+ *
+ *                           | Playing to 1 device                            | Playing to 2 devices
+ * device-prevent-playback=1 | Playback stops, device selected but grayed out | Playback stops on device, continues on other device, device selected but grayed out
+ * device-prevent-playback=0 | Playback does not resume, device not grayed    | Playback resumes on device, device not grayed
+ * (device-busy does the same)
+ *
+ * device-prevent-playback=1 | (same)                                         | (same)
+ * device-busy=1             | (no change)                                    | (no change)
+ * device-prevent-playback=0 | Playback does not resume, device still grayed  | Playback does not resume, device still grayed
+ * device-busy=0             | Playback does not resume, device not grayed    | Playback resumes on device, device not grayed
+ * (same if vice versa, ie busy=1 first)
+ *
+ */
+static enum command_state
+speaker_prevent_playback_set(void *arg, int *retval)
+{
+  struct speaker_attr_param *param = arg;
+  struct output_device *device;
+
+  device = outputs_device_get(param->spk_id);
+  if (!device)
+    return COMMAND_END;
+
+  device->prevent_playback = param->prevent_playback;
+
+  DPRINTF(E_DBG, L_PLAYER, "Speaker prevent playback: '%s' (id=%" PRIu64 ")\n", device->name, device->id);
+
+  if (device->prevent_playback)
+    *retval = speaker_deactivate(device);
+  else if (!device->busy)
+    *retval = speaker_activate(device);
+  else
+    *retval = 0;
+
+  if (*retval > 0)
+    return COMMAND_PENDING; // async
+
+  return COMMAND_END;
+}
+
+static enum command_state
+speaker_prevent_playback_set_bh(void *arg, int *retval)
+{
+  struct speaker_attr_param *param = arg;
+
+  if (output_sessions == 0)
+    {
+      DPRINTF(E_INFO, L_PLAYER, "Ending playback, speaker (id=%" PRIu64 ") set 'busy' or 'prevent-playback' flag\n", param->spk_id);
+      pb_abort(); // TODO Would be better for the user if we paused, but we don't have a handy function for that
+    }
+
+  *retval = 0;
+  return COMMAND_END;
+}
+
+static enum command_state
+speaker_busy_set(void *arg, int *retval)
+{
+  struct speaker_attr_param *param = arg;
+  struct output_device *device;
+
+  device = outputs_device_get(param->spk_id);
+  if (!device)
+    return COMMAND_END;
+
+  device->busy = param->busy;
+
+  DPRINTF(E_DBG, L_PLAYER, "Speaker busy: '%s' (id=%" PRIu64 ")\n", device->name, device->id);
+
+  if (device->busy)
+    *retval = speaker_deactivate(device);
+  else if (!device->prevent_playback)
+    *retval = speaker_activate(device);
+  else
+    *retval = 0;
+
+  if (*retval > 0)
+    return COMMAND_PENDING; // async
+
+  return COMMAND_END;
+}
+
 static enum command_state
 volume_set(void *arg, int *retval)
 {
@@ -2685,7 +2780,7 @@ static void debug_print_speaker()
 static enum command_state
 volume_setrel_speaker(void *arg, int *retval)
 {
-  struct volume_param *vol_param = arg;
+  struct speaker_attr_param *vol_param = arg;
   struct output_device *device;
   uint64_t id;
   int relvol;
@@ -2734,7 +2829,7 @@ volume_setrel_speaker(void *arg, int *retval)
 static enum command_state
 volume_setabs_speaker(void *arg, int *retval)
 {
-  struct volume_param *vol_param = arg;
+  struct speaker_attr_param *vol_param = arg;
   struct output_device *device;
   uint64_t id;
   int volume;
@@ -2791,7 +2886,7 @@ volume_setabs_speaker(void *arg, int *retval)
 static enum command_state
 volume_update_speaker(void *arg, int *retval)
 {
-  struct volume_param *vol_param = arg;
+  struct speaker_attr_param *vol_param = arg;
   struct output_device *device;
   int volume;
 
@@ -2802,10 +2897,10 @@ volume_update_speaker(void *arg, int *retval)
       return COMMAND_END;
     }
 
-  volume = outputs_device_volume_to_pct(device, vol_param->value); // Only converts
+  volume = outputs_device_volume_to_pct(device, vol_param->volstr); // Only converts
   if (volume < 0)
     {
-      DPRINTF(E_LOG, L_DACP, "Could not parse volume '%s' in update_volume() for speaker '%s'\n", vol_param->value, device->name);
+      DPRINTF(E_LOG, L_DACP, "Could not parse volume '%s' in update_volume() for speaker '%s'\n", vol_param->volstr, device->name);
       *retval = -1;
       return COMMAND_END;
     }
@@ -3158,6 +3253,38 @@ player_speaker_disable(uint64_t id)
   return ret;
 }
 
+int
+player_speaker_prevent_playback_set(uint64_t id, bool prevent_playback)
+{
+  struct speaker_attr_param param;
+  int ret;
+
+  param.spk_id = id;
+  param.prevent_playback = prevent_playback;
+
+  ret = commands_exec_sync(cmdbase, speaker_prevent_playback_set, speaker_prevent_playback_set_bh, &param);
+
+  listener_notify(LISTENER_SPEAKER | LISTENER_VOLUME);
+
+  return ret;
+}
+
+int
+player_speaker_busy_set(uint64_t id, bool busy)
+{
+  struct speaker_attr_param param;
+  int ret;
+
+  param.spk_id = id;
+  param.busy = busy;
+
+  ret = commands_exec_sync(cmdbase, speaker_busy_set, speaker_prevent_playback_set_bh, &param);
+
+  listener_notify(LISTENER_SPEAKER | LISTENER_VOLUME);
+
+  return ret;
+}
+
 int
 player_volume_set(int vol)
 {
@@ -3179,7 +3306,7 @@ player_volume_set(int vol)
 int
 player_volume_setrel_speaker(uint64_t id, int relvol)
 {
-  struct volume_param vol_param;
+  struct speaker_attr_param vol_param;
   int ret;
 
   if (relvol < 0 || relvol > 100)
@@ -3198,7 +3325,7 @@ player_volume_setrel_speaker(uint64_t id, int relvol)
 int
 player_volume_setabs_speaker(uint64_t id, int vol)
 {
-  struct volume_param vol_param;
+  struct speaker_attr_param vol_param;
   int ret;
 
   if (vol < 0 || vol > 100)
@@ -3215,13 +3342,13 @@ player_volume_setabs_speaker(uint64_t id, int vol)
 }
 
 int
-player_volume_update_speaker(uint64_t id, const char *value)
+player_volume_update_speaker(uint64_t id, const char *volstr)
 {
-  struct volume_param vol_param;
+  struct speaker_attr_param vol_param;
   int ret;
 
   vol_param.spk_id = id;
-  vol_param.value  = value;
+  vol_param.volstr  = volstr;
 
   ret = commands_exec_sync(cmdbase, volume_update_speaker, NULL, &vol_param);
   return ret;

src/player.h

@@ -40,6 +40,9 @@ struct player_speaker_info {
   bool requires_auth;
   bool needs_auth_key;
 
+  bool prevent_playback;
+  bool busy;
+
   bool has_video;
 };
 
@@ -102,6 +105,12 @@ player_speaker_enable(uint64_t id);
 int
 player_speaker_disable(uint64_t id);
 
+int
+player_speaker_prevent_playback_set(uint64_t id, bool prevent_playback);
+
+int
+player_speaker_busy_set(uint64_t id, bool busy);
+
 int
 player_playback_start(void);
 
@@ -136,7 +145,7 @@ int
 player_volume_setabs_speaker(uint64_t id, int vol);
 
 int
-player_volume_update_speaker(uint64_t id, const char *value);
+player_volume_update_speaker(uint64_t id, const char *volstr);
 
 int
 player_repeat_set(enum repeat_mode mode);