Cache Server Buffer Filling for Media Channel Change Delay

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Solution Overview

Problem

In communication networks, the instability of data stream transmission due to varying network quality leads to intermittent playback of media content, necessitating large buffers that increase delay when switching between content, particularly in wireless networks.

Innovation Solution

A client device method that receives video data from both a video server and a cache server, where past video data is transmitted in a backward manner to quickly fill the buffer to a predetermined threshold, allowing for seamless playback and reducing channel change delay by combining data from both sources based on sequence numbers, with optional central control for resource management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a large buffer size is used to compensate for unstable transmission, then playback smoothness is improved, but the delay when switching to media content increases

Engineering Contradiction:
Improveplayback smoothnessVSAvoidbuffering delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The cache server performs preliminary actions by caching media content data in advance before the client device needs it. When a client requests content, the cache server can immediately provide previously cached data, eliminating the need for the client to buffer large amounts of data locally. This preliminary caching action resolves the contradiction by providing playback data without requiring large local buffers.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The cache server acts as an intermediary between the media content source and the client device. It receives and stores content data, then serves it to clients when needed. This intermediary approach allows clients to receive content without maintaining large buffers, as the cache server handles the data storage and retrieval, thus reducing both buffer requirements and switching delays while maintaining playback smoothness.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If more buffer data is buffered before playback, then playback continuity is improved, but the time required to switch between content increases

Engineering Contradiction:
Improveplayback continuityVSAvoidchannel change time
Core Design Contradiction:
Stability of the object's compositionVSDuration of action of moving object

Solution Approach 1:

The cache server pre-loads and caches content data in advance, so when a channel change is requested, the data is already available for immediate playback. This eliminates the need for lengthy buffering periods during channel changes, maintaining playback continuity while significantly reducing channel change time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts content delivery based on client needs. The cache server can provide data at varying rates and from different time positions in the content stream, allowing flexible playback resumption without fixed buffering requirements. This dynamic approach enables quick channel changes while maintaining playback continuity.

Inventive Principle:
Principle #15Dynamics

3Reliability

If a predefined buffer size is used to handle erratic network delivery, then playback stability is improved, but the system complexity increases

Engineering Contradiction:
Improveplayback stabilityVSAvoidbuffer management complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The cache server serves as an intermediary that handles the complexity of buffer management and network variability. Instead of each client device needing complex buffer management logic to handle erratic network delivery, the cache server absorbs these complexities by pre-caching content and managing data delivery, simplifying the client device while maintaining playback stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The cache server autonomously manages content caching, storage, and retrieval operations. It self-adjusts to network conditions and client requests without requiring complex coordination with each client device. This self-service approach maintains playback stability while reducing the complexity burden on the client-side buffer management system.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2192740B1Method and apparatus for receiving content
Publication Date: 2012.06.20 THOMSON LICENSING SA
  • EP2192740B1 patent drawingFigure 1
  • EP2192740B1 patent drawingFigure 2
  • EP2192740B1 patent drawingFigure 3

AI summary

A method is provided for a client device to receive a content comprising steps of sending a request for the content, and in response to said request, receiving data of said content starting at a given time position of said content, said content is carried in a data stream from a first device, and receiving data of said content corresponding to a time position prior to said given time position of said content from at least one second device. Thus, it reduces the delay when changing to a content.