Extension – Grouping
Grouping is about collecting a set of entities in the model and giving it an identity. The
Source is a form of grouping that collects a set of
Flows that share the properties defined by the
Source. The grouping in this section is more about grouping entities that have a common purpose and are intended to be used together.
Some common examples of grouping are:
Flows that share a
Time Contextand are therefore synchronised. For example, an audio, video and subtitle group which constitutes a TV programme.
- Grouping of ISOs or sets of time-coincident audio assets related to a recording session.
- Grouping of tracks that make up a media file.
There are a number of aspects that need to be considered when defining a group and its members, such as:
- Define a group identifier that is unique.
- Define a locally unique label for each member of the group. This label along with the group identifier is used to refer to a group member.
- Define how a group member references the entity it represents. For example, by using a
SourceID to refer to a
Source, or a track index to refer to a track in a media file.
- Define whether the group members are ordered or not.
- Define how the group relates to entities such as
Flow. For example, if a group defines the members of a multi-channel audio
Sourcethen it is necessary to define how and when the group is used when recording an ancestry relationship for this content.