Adaptive HTTP Streaming MPD Segmentation for Time Shift Playback
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Solution Overview
Problem
In adaptive HTTP streaming, providing time shift playback for live media presentations is challenging due to the limitations of media presentation description (MPD) updates, which result in increased network load and inability to seek back to earlier time points, especially when the MPD includes a longer duration, affecting playback and seek operations.
Innovation Solution
A method and system that allow clients to request and acquire MPD updates dynamically, including media presentation information for additional time periods, enabling seamless time shift playback by determining the media segment's time range and selecting appropriate MPD information for requested segments, thereby supporting larger time ranges without significantly increasing MPD size or network load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the MPD includes media presentation description information for all time periods since the live broadcast starts, then the client can access the complete playlist from the beginning, but the size of the MPD increases gradually and the network load increases due to frequent updates of larger MPD files
Solution Approach 1:
The patent divides the MPD structure into multiple time period segments (e.g., first time period, second time period, third time period) with each segment containing media presentation description information for a specific duration. This segmentation allows the client to access only the necessary time period segments for time-shift playback without requiring the entire playlist, thereby reducing MPD file size and network load while maintaining the ability to seek back to earlier time points within the segmented structure
2Quantity of substance
If the MPD includes only media presentation description information for a short time period close to the current time point, then the MPD size remains small and network load is reduced, but the client cannot seek back to earlier time points
Solution Approach 1:
The patent implements a nested MPD structure where multiple MPD documents are organized in a hierarchical manner. Each MPD contains media presentation description information for a specific time period and includes references to previous MPD documents. This nesting allows the client to access historical time periods by traversing the nested structure, enabling time-shift playback and seek operations while keeping each individual MPD file size manageable
3Reliability
If the MPD is updated frequently to provide current media presentation information, then the client can access up-to-date content, but the accumulation of frequent updates with larger sizes brings considerable network load
Solution Approach 1:
The patent implements periodic updates of MPD documents for different time period segments at different intervals. Current time period MPD is updated frequently to ensure availability of latest content, while historical time period MPDs are updated less frequently. This periodic update strategy ensures the client can access current content reliably while reducing the accumulated network load from frequent large-scale updates
Data Source
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AI summary
The present invention discloses a method, an apparatus, and a system for supporting time shift playback and seamless switching between live broadcast and Video on Demand in an adaptive HTTP streaming transmission solution. The method includes: sending a live MPD request message to a media server; receiving a response message that includes MPD for a current time period and is returned by the media server, where the MPD further includes media presentation information for another time period; determining that a moment of a media segment to be requested currently exceeds a time range corresponding to the MPD, and determining, according to the media presentation information for another time period, the media presentation information corresponding to the media segment to be requested currently; acquiring the corresponding MPD according to the media presentation information corresponding to the media segment to be requested currently, and requesting, from the media server according to the acquired corresponding MPD, the media segment to be requested currently. In this manner, a client supports time shift and playback of a larger time range, and at the same time, the size of the MPD is capable of remaining in an acceptable range.