meta: add metadata features

Add a new features property to the metadata param. This should be
of type CHOICE_FEATURES_Int and should contain the extra features
supported by this metadata.

Make a special features metadata type that is a combination of the
metadata type in the upper 16 bits and the features for that type in the
lower 16 bits. Make a function to search if a type has certain feature
bits.

On the server, when negotiating buffers and metadata, check the result
of the features after filtering and if they are not 0, place them as
0 sized extra feature metadata on the buffer.

Add some metadata features for the sync_timeline, one that specifies
that the RELEASE flag is supported. With this in place, a producer can
see if a consumer supports the UNSCHEDULED_RELEASE flag.

See #4885

spa/include/spa/buffer/buffer.h

@@ -118,6 +118,17 @@ SPA_API_BUFFER void *spa_buffer_find_meta_data(const struct spa_buffer *b, uint3
 	return NULL;
 }
 
+SPA_API_BUFFER bool spa_buffer_has_meta_features(const struct spa_buffer *b, uint32_t type, uint32_t features)
+{
+	uint32_t i;
+	for (i = 0; i < b->n_metas; i++) {
+		uint32_t t = b->metas[i].type;
+		if ((t >> 16) == type && (t & features) == features)
+			return true;
+	}
+	return false;
+}
+
 /**
  * \}
  */

spa/include/spa/buffer/meta.h

@@ -37,10 +37,17 @@ enum spa_meta_type {
 	SPA_META_Busy,			/**< don't write to buffer when count > 0 */
 	SPA_META_VideoTransform,	/**< struct spa_meta_transform */
 	SPA_META_SyncTimeline,		/**< struct spa_meta_sync_timeline */
-
 	_SPA_META_LAST,			/**< not part of ABI/API */
+
+	SPA_META_START_custom		= 0x200,
+
+	SPA_META_START_features		= 0x10000,	/* features start, these have 0 size, the
+							 * type in the upper 16 bits and a bitmask in
+							 * the lower 16 bits with type specific features. */
 };
 
+#define SPA_META_TYPE_FEATURES(type,features)	(((type)<<16)|(features))
+
 /**
  * A metadata element.
  *
@@ -183,6 +190,8 @@ struct spa_meta_videotransform {
  * this metadata as SPA_PARAM_BUFFERS_metaType when negotiating a buffer
  * layout with 2 extra fds.
  */
+#define SPA_META_FEATURE_SYNC_TIMELINE_RELEASE	(1<<0)	/**< metadata supports RELEASE */
+
 struct spa_meta_sync_timeline {
 #define SPA_META_SYNC_TIMELINE_UNSCHEDULED_RELEASE	(1<<0)	/**< this flag is set by the producer and cleared
 								  *  by the consumer when it promises to signal

spa/include/spa/param/buffers.h

@@ -33,6 +33,7 @@ enum spa_param_meta {
 	SPA_PARAM_META_START,
 	SPA_PARAM_META_type,		/**< the metadata, one of enum spa_meta_type (Id enum spa_meta_type) */
 	SPA_PARAM_META_size,		/**< the expected maximum size the meta (Int) */
+	SPA_PARAM_META_features,	/**< meta data features (Features Int) */
 };
 
 /** properties for SPA_TYPE_OBJECT_ParamIO */

src/pipewire/buffers.c

@@ -221,12 +221,12 @@ int pw_buffers_negotiate(struct pw_context *context, uint32_t flags,
 	if ((res = param_filter(result, &input, &output, SPA_PARAM_Meta, &b)) > 0)
 		n_params += res;
 
-	metas = alloca(sizeof(struct spa_meta) * n_params);
+	metas = alloca(sizeof(struct spa_meta) * n_params * 2);
 
 	n_metas = 0;
 	params = alloca(n_params * sizeof(struct spa_pod *));
 	for (i = 0, offset = 0; i < n_params; i++) {
-		uint32_t type, size;
+		uint32_t type, size, features = 0;
 
 		params[i] = SPA_PTROFF(buffer, offset, struct spa_pod);
 		spa_pod_fixate(params[i]);
@@ -239,7 +239,8 @@ int pw_buffers_negotiate(struct pw_context *context, uint32_t flags,
 		if (spa_pod_parse_object(params[i],
 					SPA_TYPE_OBJECT_ParamMeta, NULL,
 					SPA_PARAM_META_type, SPA_POD_Id(&type),
-					SPA_PARAM_META_size, SPA_POD_Int(&size)) < 0) {
+					SPA_PARAM_META_size, SPA_POD_Int(&size),
+					SPA_PARAM_META_features, SPA_POD_OPT_Int(&features)) < 0) {
 			pw_log_warn("%p: invalid Meta param", result);
 			continue;
 		}
@@ -250,6 +251,11 @@ int pw_buffers_negotiate(struct pw_context *context, uint32_t flags,
 		metas[n_metas].type = type;
 		metas[n_metas].size = size;
 		n_metas++;
+		if (features != 0) {
+			metas[n_metas].type = SPA_META_TYPE_FEATURES(type, features);
+			metas[n_metas].size = 0;
+			n_metas++;
+		}
 	}
 
 	max_buffers = context->settings.link_max_buffers;