ATSC 3.0 Receiver Segment Timeline Signaling for Fast Channel Change
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Solution Overview
Problem
ATSC 3.0 systems face challenges in channel change speed and robustness against packet loss, particularly for mobile receivers where clock synchronization with the broadcaster is not feasible, leading to delays in accessing new broadcast channels and potential errors in media segment delivery.
Innovation Solution
Implementing a digital television system with segment timeline signaling that allows receivers to access and play slightly older content from a computer network while buffering broadcast media, enabling fast channel changes and opportunistic repair of damaged segments by removing the last 'N' segments from the segment timeline data structure and replenishing them when necessary, allowing seamless switching between broadband and broadcast sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the receiver waits for broadcast segments to arrive before playback, then content synchronization is maintained, but channel change latency increases
Solution Approach 1:
The receiver performs preliminary actions by accessing and buffering segments from the computer network before the broadcast segments arrive. The MPD is modified to indicate network locations of segments that can be obtained in advance, allowing the receiver to prepare content proactively rather than reactively waiting for broadcast delivery.
Solution Approach 2:
A computer network serves as an intermediary between the broadcaster and the receiver, providing an alternative path for content delivery. The hybrid approach uses both broadcast and network paths, with the network acting as a mediator to supply segments when broadcast delivery would cause delays.
2Measurement precision
If the receiver uses clock synchronization to determine live edge position, then accurate content positioning is achieved, but mobile receivers cannot maintain synchronization
Solution Approach 1:
The dependency on clock synchronization is extracted and removed from the system. Instead of requiring synchronized clocks between broadcaster and receiver, the solution uses explicit segment timeline information that can be obtained from the MPD, making the system independent of clock synchronization while maintaining accurate live edge positioning.
Solution Approach 2:
The segment timeline information is copied from the broadcast MPD to the modified MPD that indicates network locations. This copying allows mobile receivers to obtain accurate positioning information without needing to maintain clock synchronization with the broadcaster.
3Productivity
If the receiver buffers broadcast media while playing network content, then channel change speed improves, but system complexity increases
Solution Approach 1:
The system dynamically switches between network and broadcast sources based on content availability and timing. The MPD is dynamically modified to indicate which segments should be obtained from the network versus waiting for broadcast delivery, allowing flexible adaptation to different scenarios without requiring complex manual configuration.
Data Source
AI summary
Techniques are described for expanding and/or improving the Advanced Television Systems Committee (ATSC) 3.0 television protocol in robustly delivering the next generation broadcast television services. Signaling indicates where the first few segments of a changed-to broadcast service can be obtained on the broadband network. Segments not including the live edge segments are downloaded and played immediately to reduce perceived latency in the service change until the broadcast segments arrive for presentation.