Distributed Multistage Statistical Multiplexing Architecture
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Solution Overview
Problem
Existing statistical multiplexing schemes struggle to efficiently manage a large number of video channels, particularly in dense multiplexing systems, due to bandwidth and power limitations, requiring improved methods for allocating bits and adjusting quality levels across multiple video channels.
Innovation Solution
A distributed, multistage multiplexing architecture is implemented, where a second stage multiplexer controls bandwidth allocation among a plurality of encoders through a bandwidth request process, allowing for modular and scalable statistical multiplexing with a constant output transport rate, and enabling the addition or deletion of services without impacting other channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large number of video channels are multiplexed in a dense multiplexing system, then the number of services increases, but bandwidth allocation and quality control become more difficult to manage
Solution Approach 1:
The multiplexing system is divided into multiple independent first stage multiplexers, each handling a subset of video channels. This segmentation allows manageable complexity at each stage while supporting a large total number of services across the entire system.
Solution Approach 2:
The patent introduces a two-stage multiplexing architecture that adds a temporal dimension to the multiplexing process. First stage multiplexers operate independently in parallel, then their outputs are combined by second stage multiplexers, creating a hierarchical structure that manages complexity through dimensional organization.
2Manufacturing precision
If bandwidth is dynamically allocated based on video complexity, then video quality is improved, but system complexity increases
Solution Approach 1:
The system implements bandwidth allocation at multiple stages rather than attempting to optimize all channels simultaneously. First stage multiplexers perform partial optimization on their assigned channels, then second stage multiplexers perform additional optimization on the combined stream, achieving high video quality through incremental partial actions.
Solution Approach 2:
The patent introduces intermediary elements including bandwidth request messages and bandwidth allocation messages that mediate between video complexity requirements and actual bandwidth allocation. These intermediary communication protocols enable dynamic quality adjustment without requiring complex direct control of each encoder.
3Adaptability or versatility
If services are added or deleted from the multiplexed stream, then system flexibility improves, but multiplexing stability is disrupted
Solution Approach 1:
The system performs preliminary actions by maintaining constant output transport rates at first stage multiplexers and using null packets to fill bandwidth gaps. This preliminary structuring creates a stable foundation that allows services to be added or deleted without disrupting the overall multiplexing stability.
Solution Approach 2:
The patent employs discarding and recovering mechanisms where null packets are discarded when bandwidth is available and recovered (added) when bandwidth needs to be reserved for additional services. This dynamic discarding and recovering of null packets maintains multiplexing stability while enabling service flexibility.
Data Source
AI summary
The present invention provides methods and apparatus for statistical multiplexing of a large number of data streams. A plurality of encoders are associated with each first stage multiplexer. Bandwidth allocation among all encoders is controlled by a second stage multiplexer. A bandwidth request message is communicated from each the encoders to the second stage multiplexer. The second stage multiplexer allocates available bandwidth based on the bandwidth request messages. The second stage multiplexer then communicates an allocated bandwidth message to each encoder. Each encoder encodes a data stream in accordance with its allocated bandwidth to provide an encoded data stream. A plurality of the encoded data streams are multiplexed at each first stage multiplexer to provide a multiplexed data stream at a constant data rate. The second stage multiplexer mutiplexes the multiplexed data streams from the first stage multiplexers to provide a multiplexed transport stream.