Hardware Multiplexer Data Rate Estimation
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Solution Overview
Problem
Software-based data rate estimation for video streams is slow, necessitating a hardware-based mechanism for efficient multiplexing of packetized video streams.
Innovation Solution
A multiplexing system comprising an input unit, storage unit, and control unit that extracts timestamp values from packets, computes data rate estimates, and adjusts scheduling rates for MPEG-2 transport streams, using a rate data table and local clock samples to manage packet allocation into a multiplexed output stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If software-based data rate estimation is used, then implementation flexibility is maintained, but processing speed is slow
Solution Approach 1:
The patent replaces software-based data rate estimation with a hardware-based mechanism. The control unit uses hardware circuits to extract timestamp values from packets, count packets between timestamps, and compute data rates using the formula Rate = (Count × Packet_Size) / (Timestamp2 - Timestamp1). This hardware implementation significantly increases processing speed while managing complexity through dedicated functional blocks for each computation step.
Solution Approach 2:
The hardware mechanism automatically performs data rate estimation without requiring external software intervention. The control unit continuously monitors incoming packets, extracts timestamps, maintains packet counts, and computes data rates in real-time using embedded logic and storage elements, enabling self-sufficient operation at high speed.
2Productivity
If hardware-based data rate estimation is implemented, then processing speed increases, but system complexity increases
Solution Approach 1:
The control unit is divided into distinct functional segments: a timestamp extraction module that retrieves timestamps from packet headers, a packet counting module that tracks packets between timestamps, and a data rate computation module that calculates rates using stored values. Each segment handles a specific task, improving throughput while managing complexity through functional decomposition.
Solution Approach 2:
The patent introduces intermediate storage elements (registers or memory locations) to hold timestamp values and packet counts between computations. These intermediaries buffer data between extraction, counting, and computation stages, enabling parallel operation and high throughput without requiring complex real-time coordination between functional blocks.
3Reliability
If real-time data rate estimation is performed, then multiplexing efficiency is improved, but computational requirements increase
Solution Approach 1:
The control unit performs preliminary actions by extracting and storing timestamp values as soon as they appear in packets, and by continuously maintaining packet counts in ready state. When a new timestamp is received, the data rate computation immediately uses the pre-stored previous timestamp and current packet count, enabling real-time accurate multiplexing decisions without intensive on-the-fly computation.
Solution Approach 2:
The system changes computational parameters by using simple arithmetic operations (multiplication and division) rather than complex algorithms. The data rate is computed using the straightforward formula Rate = (Count × Packet_Size) / (Timestamp2 - Timestamp1), which requires minimal computational resources and energy while providing accurate real-time multiplexing control.
Data Source
AI summary
A multiplexing system having an input unit, a storage unit and control unit. The input unit receives data units corresponding to multiple source data streams and extracts packets from the data units. The control unit computes data rate estimates for the source data streams based on timestamps in the source data streams. The storage unit stores a packet count and previous timestamp value for each source data stream. The control unit computes a preliminary data rate estimate for a source data stream based on samples of a local clock if timestamps are not received promptly. The control unit also computes scheduling rates based on the data rate estimates. The scheduling rates are used to control the rates of allocation of data from the source data streams into a multiplexed output stream. The control unit computes scheduling rates in a way that avoids oversubscription of the output channel.