ATSC 3.0 MPD XLink Empty Period for Replacement Content Signaling
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Solution Overview
Problem
In the Advanced Television Systems Committee (ATSC) 3.0, signaling replaceable content using XLink in SegmentTimeline templates is complicated due to the requirement that all listed DASH segments must be available at the time of MPD delivery, making it difficult to signal future replaceable content without breaking receiver functionality.
Innovation Solution
The solution involves constructing an MPD with a second future period containing no segments but including an XLink, allowing receivers to prepare for replacement content by fetching it in advance, and notifying broadcaster applications to cache the content, enabling seamless replacement without disrupting ongoing media playback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If an XLink is inserted in a future period to trigger replacement content, then replacement content can be signaled in advance, but receivers that tune in with the future period already in place may assume the live point is at the end of the XLink marked future period and fail
Solution Approach 1:
The patent applies preliminary action by inserting an empty period with an XLink marker before the actual replacement content period. This allows receivers to prepare for and fetch replacement content in advance without disrupting their assumption about where the live point should be. The empty period serves as a preparation phase that doesn't interfere with receiver timing calculations while still enabling advance content fetching.
Solution Approach 2:
The empty period with XLink acts as an intermediary element between the current content and the future replacement content. It provides a transitional mechanism that signals to receivers that replacement content will be available without causing them to misinterpret the live point location. This intermediary structure resolves the conflict between providing advance notice and maintaining receiver reliability.
2Adaptability or versatility
If SegmentTimeline template is used to list all DASH segments, then all segments must be available at MPD delivery time, but this makes it difficult to signal future replaceable content
Solution Approach 1:
The patent segments the MPD structure by introducing an empty period as a separate entity between the current content period and the future replacement content period. This segmentation allows the SegmentTimeline to maintain its requirement for all segments to be available while still enabling future replacement content signaling through the XLink in the empty period. The segmentation creates a structural solution that satisfies both constraints.
Solution Approach 2:
By using an empty period with an XLink marker, the system performs preliminary action to signal future replacement content without requiring the actual replacement segments to be available yet. This allows the MPD to be delivered with all current segments available while preparing receivers for future content replacement, effectively decoupling the signaling mechanism from the content availability requirement.
3Measurement precision
If the last segment in SegmentTimeline is made available for presentation, then the live point is correctly identified, but any replaceable content must follow the last segment which complicates XLink usage
Solution Approach 1:
The empty period with XLink serves as an intermediary that separates the live point identification (last segment of current period) from the replacement content signaling. This intermediary structure allows receivers to correctly identify the live point while providing a clean mechanism for signaling replacement content without requiring complex XLink operations on the actual content segments. The complexity is isolated to the empty period structure rather than the content segments.
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. An empty x-link period is provided at the end of an MPD to alert a newly tuning in receiver to obtain and insert a replacement ad in the period.