RepresentationID

RepresentationID is an identifier used in media delivery systems to distinguish among multiple representations of a resource, such as different encodings of a video stream. The identifier is typically a string or number associated with a Representation within a collection, for example within an AdaptationSet in MPEG-DASH. The Representation element in the manifest includes an id attribute that serves as the local identifier for that variant; it is used by the client to switch between representations during adaptive streaming. Unlike the bandwidth or resolution attributes, the ID is an opaque label used by the client to refer to a specific representation.

In MPEG-DASH, the MPD's Representation element has an id; the client can reference a representation by this id as part of its segment requests and switching logic. The id should be unique within the AdaptationSet and is typically intended to remain stable across manifest updates to enable smooth switching. When a representation is removed or replaced, the handling of its ID should be documented to avoid confusion or misrouting of requests.

In other standards and systems, RepresentationID can serve a similar role as a stable handle to a specific variant of a resource; the exact syntax and scope vary by specification. It is common for implementations to prefer human-readable or semantically meaningful IDs, while maintaining strict uniqueness within the relevant scope.

Best practices include ensuring uniqueness within scope, keeping IDs stable across updates when possible, and avoiding reuse of an ID for a different variant to preserve consistent reference in client logic.