diff --git a/spa/include/spa/format-builder.h b/spa/include/spa/format-builder.h
index 8a7a44ced..1585a49df 100644
--- a/spa/include/spa/format-builder.h
+++ b/spa/include/spa/format-builder.h
@@ -52,7 +52,7 @@ spa_pod_builder_push_format(struct spa_pod_builder *builder,
 	spa_pod_builder_object(b, f, 0, format_type,				\
 		SPA_POD_TYPE_ID,media_type,					\
 		SPA_POD_TYPE_ID,media_subtype,					\
-		__VA_ARGS__)
+		## __VA_ARGS__)
 
 #ifdef __cplusplus
 }  /* extern "C" */
diff --git a/spa/include/spa/format-utils.h b/spa/include/spa/format-utils.h
index 1327a4456..74144da7c 100644
--- a/spa/include/spa/format-utils.h
+++ b/spa/include/spa/format-utils.h
@@ -114,6 +114,7 @@ struct spa_type_media_subtype_audio {
 	uint32_t g729;
 	uint32_t amr;
 	uint32_t gsm;
+	uint32_t midi;
 };
 
 static inline void
@@ -133,6 +134,7 @@ spa_type_media_subtype_audio_map(struct spa_type_map *map,
 		type->g729 = spa_type_map_get_id(map, SPA_TYPE_MEDIA_SUBTYPE__g729);
 		type->amr = spa_type_map_get_id(map, SPA_TYPE_MEDIA_SUBTYPE__amr);
 		type->gsm = spa_type_map_get_id(map, SPA_TYPE_MEDIA_SUBTYPE__gsm);
+		type->midi = spa_type_map_get_id(map, SPA_TYPE_MEDIA_SUBTYPE__midi);
 	}
 }
 
diff --git a/spa/include/spa/format.h b/spa/include/spa/format.h
index cf1780130..4f4d72c14 100644
--- a/spa/include/spa/format.h
+++ b/spa/include/spa/format.h
@@ -75,6 +75,7 @@ struct spa_format;
 #define SPA_TYPE_MEDIA_SUBTYPE__g729		SPA_TYPE_MEDIA_SUBTYPE_BASE "g729"
 #define SPA_TYPE_MEDIA_SUBTYPE__amr		SPA_TYPE_MEDIA_SUBTYPE_BASE "amr"
 #define SPA_TYPE_MEDIA_SUBTYPE__gsm		SPA_TYPE_MEDIA_SUBTYPE_BASE "gsm"
+#define SPA_TYPE_MEDIA_SUBTYPE__midi		SPA_TYPE_MEDIA_SUBTYPE_BASE "midi"
 
 struct spa_format_body {
 	struct spa_pod_object_body obj_body;
diff --git a/spa/plugins/alsa/alsa-sink.c b/spa/plugins/alsa/alsa-sink.c
index c35a6487a..b638193c0 100644
--- a/spa/plugins/alsa/alsa-sink.c
+++ b/spa/plugins/alsa/alsa-sink.c
@@ -32,7 +32,7 @@
 #define CHECK_PORT(this,d,p)    ((d) == SPA_DIRECTION_INPUT && (p) == 0)
 
 static const char default_device[] = "hw:0";
-static const uint32_t default_min_latency = 1024;
+static const uint32_t default_min_latency = 128;
 
 static void reset_props(struct props *props)
 {
diff --git a/src/modules/module-jack.c b/src/modules/module-jack.c
index 6fd5a2295..6b8af786f 100644
--- a/src/modules/module-jack.c
+++ b/src/modules/module-jack.c
@@ -126,23 +126,32 @@ struct link {
 
 static bool init_socket_name(struct sockaddr_un *addr, const char *name, bool promiscuous, int which)
 {
-	int name_size;
+	int name_size, i;
 	const char *runtime_dir;
+	char cname[SYNC_MAX_NAME_SIZE+1];
+
+	for (i = 0; name[i] != '\0'; i++) {
+		if (name[i] == '/' || name[i] == '\\')
+			cname[i] = '_';
+		else
+			cname[i] = name[i];
+	}
+	cname[i] = name[i];
 
 	runtime_dir = JACK_SOCKET_DIR;
 
 	addr->sun_family = AF_UNIX;
 	if (promiscuous) {
 		name_size = snprintf(addr->sun_path, sizeof(addr->sun_path),
-			     "%s/jack_%s_%d", runtime_dir, name, which) + 1;
+			     "%s/jack_%s_%d", runtime_dir, cname, which) + 1;
 	} else {
 		name_size = snprintf(addr->sun_path, sizeof(addr->sun_path),
-			     "%s/jack_%s_%d_%d", runtime_dir, name, getuid(), which) + 1;
+			     "%s/jack_%s_%d_%d", runtime_dir, cname, getuid(), which) + 1;
 	}
 
 	if (name_size > (int) sizeof(addr->sun_path)) {
 		pw_log_error("socket path \"%s/%s\" plus null terminator exceeds 108 bytes",
-			     runtime_dir, name);
+			     runtime_dir, cname);
 		*addr->sun_path = 0;
 		return false;
 	}
@@ -452,6 +461,38 @@ handle_deactivate_client(struct client *client)
 	return 0;
 }
 
+static int
+handle_set_timebase_callback(struct client *client)
+{
+	struct impl *impl = client->impl;
+	struct jack_server *server = &impl->server;
+	int result = 0;
+	int ref_num, conditional, tbm;
+
+	CheckSize(kSetTimebaseCallback_size);
+	CheckRead(&ref_num, sizeof(int));
+	CheckRead(&conditional, sizeof(int));
+
+	pw_log_debug("protocol-jack %p: kSetTimebaseCallback %d", client->impl, ref_num);
+
+	tbm = server->engine_control->transport.time_base_master;
+
+	if (conditional && tbm > 0) {
+		if (ref_num != tbm) {
+			pw_log_error("ref = %d failed: %d is already the master", ref_num, tbm);
+			result = EBUSY;
+		} else {
+			pw_log_debug("ref = %d was already timebase master", ref_num);
+		}
+	} else {
+		server->engine_control->transport.time_base_master = ref_num;
+		server->engine_control->transport.conditional = conditional;
+		pw_log_debug("new timebase master: ref = %d", ref_num);
+	}
+	CheckWrite(&result, sizeof(int));
+	return 0;
+}
+
 static int
 handle_client_check(struct client *client)
 {
@@ -863,6 +904,8 @@ process_messages(struct client *client)
 	case jack_request_GetPortNConnections:
 	case jack_request_ReleaseTimebase:
 	case jack_request_SetTimebaseCallback:
+		res = handle_set_timebase_callback(client);
+		break;
 	case jack_request_SetBufferSize:
 	case jack_request_SetFreeWheel:
 		break;
diff --git a/src/modules/module-jack/defs.h b/src/modules/module-jack/defs.h
index 580ec2471..1bf4a952b 100644
--- a/src/modules/module-jack/defs.h
+++ b/src/modules/module-jack/defs.h
@@ -127,6 +127,7 @@ enum jack_notification_type {
 
 #define kActivateClient_size (2*sizeof(int))
 #define kDeactivateClient_size (sizeof(int))
+#define kSetTimebaseCallback_size (sizeof(int) + sizeof(int))
 #define kRegisterPort_size (sizeof(int) + JACK_PORT_NAME_SIZE+1 + JACK_PORT_TYPE_SIZE+1 + 2*sizeof(unsigned int))
 #define kClientCheck_size (JACK_CLIENT_NAME_SIZE+1 + 4 * sizeof(int))
 #define kClientOpen_size (JACK_CLIENT_NAME_SIZE+1 + 2 * sizeof(int))
diff --git a/src/modules/module-jack/jack-node.c b/src/modules/module-jack/jack-node.c
index abad97cb6..edcb99601 100644
--- a/src/modules/module-jack/jack-node.c
+++ b/src/modules/module-jack/jack-node.c
@@ -52,6 +52,7 @@ struct type {
         struct spa_type_media_subtype media_subtype;
         struct spa_type_format_audio format_audio;
         struct spa_type_audio_format audio_format;
+        struct spa_type_media_subtype_audio media_subtype_audio;
 };
 
 static inline void init_type(struct type *type, struct spa_type_map *map)
@@ -62,6 +63,7 @@ static inline void init_type(struct type *type, struct spa_type_map *map)
         spa_type_media_subtype_map(map, &type->media_subtype);
         spa_type_format_audio_map(map, &type->format_audio);
         spa_type_audio_format_map(map, &type->audio_format);
+        spa_type_media_subtype_audio_map(map, &type->media_subtype_audio);
 }
 
 struct node_data {
@@ -372,7 +374,8 @@ static int port_enum_formats(void *data,
 	                        PROP(&f[1], t->format_audio.channels, SPA_POD_TYPE_INT, 1));
 		}
 		else if (pd->port.jack_port->type_id == 1) {
-			return SPA_RESULT_ENUM_END;
+			spa_pod_builder_format(&b, &f[0], t->format,
+	                        t->media_type.audio, t->media_subtype_audio.midi);
 		}
 		else
 			return SPA_RESULT_ENUM_END;
diff --git a/src/modules/module-jack/shared.h b/src/modules/module-jack/shared.h
index 9faad39cf..da26c6e1c 100644
--- a/src/modules/module-jack/shared.h
+++ b/src/modules/module-jack/shared.h
@@ -888,7 +888,7 @@ struct jack_transport_engine {
         int time_base_master;
         bool pending_pos;
         bool network_sync;
-        bool conditionnal;
+        bool conditional;
         int32_t write_counter;
 } POST_PACKED_STRUCTURE;
 
diff --git a/src/modules/module-jack/synchro.h b/src/modules/module-jack/synchro.h
index 7f8f4a4db..4aacc0a4f 100644
--- a/src/modules/module-jack/synchro.h
+++ b/src/modules/module-jack/synchro.h
@@ -34,12 +34,22 @@ jack_synchro_init(struct jack_synchro *synchro,
 		  int value,
 		  bool promiscuous)
 {
+	char cname[SYNC_MAX_NAME_SIZE+1];
+	int i;
+	for (i = 0; client_name[i] != '\0'; i++) {
+		if (client_name[i] == '/' || client_name[i] == '\\')
+			cname[i] = '_';
+		else
+			cname[i] = client_name[i];
+	}
+	cname[i] = client_name[i];
+
 	if (promiscuous)
 		snprintf(synchro->name, sizeof(synchro->name),
-				"jack_sem.%s_%s", server_name, client_name);
+				"jack_sem.%s_%s", server_name, cname);
 	else
 		snprintf(synchro->name, sizeof(synchro->name),
-				"jack_sem.%d_%s_%s", getuid(), server_name, client_name);
+				"jack_sem.%d_%s_%s", getuid(), server_name, cname);
 
 	synchro->flush = false;
 	if ((synchro->semaphore = sem_open(synchro->name, O_CREAT | O_RDWR, 0777, value)) == (sem_t*)SEM_FAILED) {
diff --git a/src/pipewire/link.c b/src/pipewire/link.c
index 578aebc7e..85eb5e126 100644
--- a/src/pipewire/link.c
+++ b/src/pipewire/link.c
@@ -163,7 +163,7 @@ static int do_negotiate(struct pw_link *this, uint32_t in_state, uint32_t out_st
 		}
 	}
 
-	pw_log_debug("link %p: doing set format", this);
+	pw_log_debug("link %p: doing set format %p", this, format);
 	if (pw_log_level_enabled(SPA_LOG_LEVEL_DEBUG))
 		spa_debug_format(format);