Distributed VOD Server Bit Rate Control
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Solution Overview
Problem
Combining Variable Bit Rate (VBR) video streams into a Constant Bit Rate (CBR) transport stream is computationally intensive and requires efficient bit rate management to prevent exceeding the CBR limit, especially in video-on-demand services where bandwidth constraints are common.
Innovation Solution
A distributed data storage system is used for distributed processing, where data storage nodes with processing capability are instructed by a computer to perform tasks such as rate shaping, transcoding, and content processing, allowing for computation-intensive tasks like bit rate control to be distributed across multiple nodes, reducing the load on a single computer and enabling efficient bit rate management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If VBR streams are combined into a CBR transport stream with strict bit rate limiting, then the transport stream stability is improved, but the flexibility in bandwidth utilization deteriorates
Solution Approach 1:
The system dynamically adjusts the bit rate allocation among multiple VBR streams based on current bandwidth availability and stream priorities. The bit rate controller continuously monitors the combined bit rate and adjusts individual stream rates in real-time, allowing the system to adapt to changing conditions while maintaining CBR constraints.
Solution Approach 2:
The invention changes the bit rate parameter of individual VBR streams dynamically to fit the CBR transport stream constraints. By adjusting the bit rate of component streams based on their importance, current quality levels, and available bandwidth, the system maintains stability while optimizing bandwidth utilization.
2Manufacturing precision
If bit rate lowering is performed on MPEG streams through decompression and recompression, then the bit rate control precision is improved, but the computational complexity increases
Solution Approach 1:
The system performs bit rate lowering in advance before multiplexing streams into the transport stream. By pre-processing streams to reduce their bit rates to appropriate levels, the system avoids the need for complex real-time compression adjustments during multiplexing, reducing overall computational complexity.
Solution Approach 2:
The invention extracts the bit rate control function as a separate preprocessing step before multiplexing. Instead of performing complex compression during the multiplexing process, the system separates the bit rate adjustment operation from the multiplexing operation, simplifying the overall system architecture.
3Reliability
If multiple VBR streams are multiplexed into a CBR transport stream with monitoring and padding, then the transport stream stability is improved, but the bandwidth utilization efficiency deteriorates
Solution Approach 1:
The system dynamically adjusts the bit rate of individual VBR streams based on current bandwidth availability. When bandwidth is available, streams are allowed to use higher bit rates; when bandwidth is constrained, bit rates are reduced. This dynamic adjustment eliminates the need for conservative padding while maintaining CBR stability.
Solution Approach 2:
The bit rate controller implements a feedback mechanism that monitors the combined bit rate of multiplexed streams and adjusts individual stream rates accordingly. This closed-loop control ensures that the total bit rate matches the CBR constraint exactly, eliminating waste from padding while preventing overflow.
Data Source
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AI summary
A distributed stream processing system including a plurality of storage devices, at least one of which is configured to process at least one segment of a data stream, thereby producing a changed segment of the data stream, and provide output of at least the changed segment of the data stream, and a server configured to accept the output of the storage devices and combine the output into a transport stream. A method for combining a plurality of data streams including using one or more storage devices for processing at least one segment of a data stream, thereby producing a changed segment of the data stream, and providing output of at least the changed segment of the data stream, and combining the output of the storage devices into a combined data stream. Related apparatus and methods are also described.