Cache Server Synchronization for HbbTV Media Streams
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Solution Overview
Problem
Existing methods for synchronizing primary and secondary media streams, such as those used in Hybrid Broadcast Broadband TV (HBBTV), face challenges due to differences in data formats and network delays, leading to delayed secondary stream availability and a degraded user experience, particularly when secondary content is generated after the primary stream is received.
Innovation Solution
A method and system that utilize a cache server to provide cache data units associated with a common content timeline, allowing media processing devices to instantly synchronize primary and secondary streams by transmitting pre-broadcasted data units from the primary stream, thereby reducing the secondary stream delay and improving user experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the secondary stream is created after the primary stream is received by a third-party content creator, then the secondary content can be generated with full access to primary stream content, but the secondary stream will be delayed by several seconds relative to the primary stream
Solution Approach 1:
The patent applies preliminary action by having the cache server pre-fetch and store data units from the primary stream before the secondary stream is requested. When a user activates the secondary stream, the media processing device can immediately receive pre-cached data units from the cache server, eliminating the delay that would otherwise occur while waiting for the third-party content creator to generate the secondary content. This resolves the contradiction by preparing content in advance without compromising content accuracy.
Solution Approach 2:
The patent introduces a cache server as an intermediary between the broadcast source and the media processing device. This intermediary pre-loads and stores data units from the primary stream, making them immediately available when the secondary stream is activated. The cache server acts as a buffer that decouples the timing between primary stream reception and secondary stream generation, allowing instant synchronization without requiring the secondary content to be created in real-time by the content creator.
2Reliability
If the primary stream is delayed to allow the secondary stream to catch up, then synchronization between primary and secondary streams can be achieved, but the user experience is seriously degraded due to screen freezing or rewinding
Solution Approach 1:
The patent applies preliminary action by pre-fetching and caching data units from the primary stream before the secondary stream activation. This allows the media processing device to immediately display synchronized content without delaying the primary stream playback. The cache server prepares the necessary data units in advance, so when the user activates the secondary stream, both streams can be displayed simultaneously without screen freezing or rewinding, maintaining excellent user experience while achieving reliable synchronization.
3Loss of time
If a cache server is used to provide pre-broadcasted data units from the primary stream, then instant synchronization of primary and secondary streams can be achieved, but the system complexity increases with additional cache server infrastructure
Solution Approach 1:
The patent applies universality by designing the cache server to serve multiple functions: it acts as a content buffer for the secondary stream, a synchronization coordinator between primary and secondary streams, and a data distribution node to media processing devices. By consolidating these functions into a single multi-functional component, the system achieves instant synchronization without proportionally increasing complexity. The cache server becomes a universal hub that manages timing, storage, and distribution across the entire HbbTV system.
Data Source
AI summary
Methods, media processing devices and cache nodes for enabling instant synchronization of processing of data units of a primary media stream and of one or more secondary streams by at least one media processing device are described. The method may comprise the steps of: selecting a primary media stream that is broadcasted by a broadcast source, said primary media stream being associated with at least one secondary stream; receiving data units of said primary media stream and data units of said at least one secondary media streams; providing cache timing information associated with a time delay between the availability by said at least one media processing device to data units of said primary stream and to corresponding data units of said secondary stream; and, requesting one or more cache data units from at least one cache server on the basis of said cache timing information, wherein at least part of said cache data units correspond to data units of said primary media stream that, at the time the primary media stream was selected by said media processing device, were already broadcasted by said broadcast source.