A pg:Group MUST have exactly one string lv2:symbol. This symbol must be unique according to the same rules as the lv2:symbol for an lv2:Port, where group symbols and port symbols reside in the same namespace. In other words, a group on a plugin MUST NOT have the same symbol as another group or a port on that plugin. This makes it possible to uniquely reference a port or group on a plugin with a single identifier and no context.
A set of ports/channels/controls/etc that are are logically grouped together, e.g. two audio ports in a group may form a stereo stream. In order to avoid the need to define large numbers of identical group definitions, a group definition may be shared. For example, a plugin collection may define a single URI for a pg:StereoGroup with the symbol "input" and use it in many plugins.
A group which contains exclusively inputs.
A group which contains exclusively outputs.
An element MUST have exactly one lv2:designation.
An element of a group, which has a designation and an optional index.
Indicates that a group has a certain element (a parameter or channel designation with a possible index).
Indicates that this port or group should be considered a "side chain" of some other port or group. The precise definition of "side chain" depends on the plugin, but in general this group should be considered a modifier to some other group, rather than an independent input itself.
Indicates that this group is a child of another group. This property has no meaning with respect to plugin execution, but the host may find this information useful (e.g. to provide a compact user interface). Note that being a sub-group does not relax the restriction that the group MUST have a unique symbol with respect to the plugin.
Indicates that this port or group should be considered the "result" of some other port or group. This property only makes sense on groups with outputs when the source is a group with inputs. This can be used to convey a relationship between corresponding input and output groups with different types, e.g. a mono->stereo plugin.
Indicates that this group should be considered the "main" input, i.e. the primary task is processing the signal in this group. A plugin MUST NOT have more than one pg:mainInput property.
Indicates that this group should be considered the "main" output. The main output group SHOULD have the main input group as a pg:source.
Indicates that this port is a part of a group of ports on the plugin. The port should also have an lv2:designation property to define its designation within that group.
Discrete channel configurations. These groups are divided into channels where each represents a particular speaker location. The position of sound in one of these groups depends on a particular speaker configuration.
Ambisonic channel configurations. These groups are divided into channels which together represent a position in an abstract n-dimensional space. The position of sound in one of these groups does not depend on a particular speaker configuration; a decoder can be used to convert an ambisonic stream for any speaker configuration.
Ambisonic B stream of horizontal order 1 and peripheral order 0.
Ambisonic B stream of horizontal order 1 and peripheral order 1.
Ambisonic B stream of horizontal order 2 and peripheral order 0.
Ambisonic B stream of horizontal order 2 and peripheral order 1.
Ambisonic B stream of horizontal order 2 and peripheral order 2.
Ambisonic B stream of horizontal order 3 and peripheral order 0.
Ambisonic B stream of horizontal order 3 and peripheral order 1.
Ambisonic B stream of horizontal order 3 and peripheral order 2.
Ambisonic B stream of horizontal order 3 and peripheral order 3.