Statistical Multiplexer Jitter Management via Packet Rearrangement

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Solution Overview

Problem

Statistical multiplexing systems face issues with packet jitter and bandwidth management due to variable bit rates and communication channel limitations, leading to potential overflow or underflow of bandwidth, which can result in video glitches and decoding delays.

Innovation Solution

A method and system that rearrange the transmit time of select packets in encoded media streams to ensure the bandwidth of the multiplexed media stream does not exceed the available transmission channel bandwidth, using a de-jitter arrangement and prioritizing packets based on decode delay to maintain timely packet arrival without exceeding individual media stream maximum bit rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If statistical multiplexing is used to share a communication channel among multiple programs, then bandwidth utilization is improved, but packet jitter occurs when IP communication is employed

Engineering Contradiction:

Improvebandwidth utilizationVSAvoidpacket timing stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

A jitter buffer is introduced as an intermediary component between the IP network and the statistical multiplexer. This buffer absorbs timing variations and jitter introduced by IP communication, providing stable packet timing to the multiplexer while maintaining efficient bandwidth utilization through statistical multiplexing

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If variable bit rate encoding is used for multiple programs, then encoding efficiency is improved, but bandwidth allocation becomes problematic due to channel limitations

Engineering Contradiction:

Improveencoding efficiencyVSAvoidbandwidth allocation

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The system implements dynamic bandwidth allocation where the statistical multiplexer continuously adjusts the bit rate allocation for each program based on current channel conditions, program complexity, and buffer status. This allows variable bit rate encoding to maintain high encoding efficiency while adapting to bandwidth constraints in real-time

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

A feedback mechanism is established where the multiplexer monitors the actual bandwidth consumption and transmission status, then adjusts the target bit rates for individual programs accordingly. This ensures that variable bit rate encoding remains efficient while preventing bandwidth overflow

Inventive Principle:

Principle #23Feedback

3Reliability

If de-jitter processing is applied to remove packet jitter, then packet timing stability is improved, but transmission delays increase

Engineering Contradiction:

Improvepacket timing stabilityVSAvoidtransmission delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The jitter buffer applies partial de-jitter processing by selectively buffering packets only when timing variations exceed a threshold, rather than buffering all packets. This provides sufficient timing stability for the multiplexer while minimizing unnecessary transmission delays

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11653041B2Jitter management in a statistical multiplexer employing an IP network

Publication Date: 2023.05.16 ARRIS ENTERPRISES LLC

AI summary

A statistical multiplexer is provided with a series of encoders that encode media streams at different bitrates to reduce jitter. The encoded media streams are transmitted to a multiplexer over a network and experience jitter that is reduced by a de-jitter arrangement. The multiplexer rearranges a transmit time of select packets in select ones of the media streams received over the network when a total group bandwidth available on the transmission channel over which the multiplexed media stream is to be transmitted is less than a sum of the bandwidths of the media streams because of the jitter and de-jitter process experienced by the media streams. The rearranging causes the bandwidth of the multiplexed media stream to be no greater than the total group bandwidth of the transmission channel without exceeding a maximum bit rate at which each individual encoded media stream is configured.