DASHing TO THE FINISH LINE Transport Layer Key to Broadband-Broadcast Convergence

ATSC 3.0 specifications are DASHing toward the finish line. Standardization efforts are not only on a fast pace, but they’re also making use of MPEG DASH (Dynamic Adaptive Streaming over HTTP) technology. DASH is a transport technology that’s widely deployed over broadband to deliver media to most consumer devices with a display. This DASH technology is now being adapted to be used over the ATSC 3.0 broadcast transport.

The same encoding of media segments can be used whether the content is being delivered over broadcast-only, or over broadcast and broadband concurrently, known as “hybrid” delivery. As broadcasters migrate online (broadband) services to DASH-based technology, ATSC 3.0 will allow them to repurpose the same encoded content over both physical transports. Use of DASH technology allows repurposing of encoder equipment and facilitates more efficient broadband delivery.

The layer just above the physical layer of ATSC 3.0 is the transport layer. This is specified in the ATSC A/331 Candidate Standard for Signaling, Delivery, Synchronization, and Error Protection. For the DASH details, ATSC formed a close liaison relationship with the DASH Industry Forum, a group of technical experts devoted to MPEG DASH interoperability worldwide. This liaison relationship resulted in a new DASH-IF publication, Guidelines for Implementation: DASH-IF Interoperability Point for ATSC 3.0, which forms a core element of A/331.