Low-Latency Streaming Clock Synchronization for Accurate ABR

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Solution Overview

Problem

Conventional Adaptive Bitrate (ABR) protocols for HTTP adaptive streaming (HAS) fail to accurately determine network bandwidth due to idle periods between chunk reception, leading to poor bitrate decisions during live events, resulting in suboptimal user experience.

Innovation Solution

A computing device synchronizes its clock with the content source using a clock reference and wall clock time to differentiate between network-limited and source-limited content chunks, accurately determining bandwidth for adaptive bitrate decisions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If chunked transfer encoding is used for low latency streaming, then latency is reduced and content can be sent in real-time, but idle periods between chunks cause inaccurate network bandwidth determination

Engineering Contradiction:
Improvestreaming latencyVSAvoidbandwidth determination accuracy
Core Design Contradiction:
Loss of timeVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by pre-synchronizing the client clock with the source clock using clock references embedded in content chunks. This clock synchronization is performed in advance to establish a reliable time base for subsequent bandwidth measurements, enabling accurate determination of whether idle periods are due to network limitations or source encoding rates, thus resolving the measurement precision issue while maintaining low latency streaming

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If conventional ABR protocols are used with chunked encoding, then adaptive bitrate streaming is enabled, but idle periods between chunks result in poor ABR decisions

Engineering Contradiction:
Improveadaptive bitrate capabilityVSAvoidABR decision accuracy
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements feedback by continuously monitoring the relationship between chunk arrival times, source clock time, and network transmission duration. This feedback mechanism allows the system to distinguish between network-limited chunks (where transmission duration exceeds media time) and source-limited chunks (where they are comparable), enabling reliable ABR decisions even during idle periods by using clock synchronization to interpret bandwidth measurements accurately

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3772220B1Methods and systems for low latency streaming
Publication Date: 2025.07.02 COMCAST CABLE COMM LLC
  • EP3772220B1 patent drawingFigure 1
  • EP3772220B1 patent drawingFigure 2A
  • EP3772220B1 patent drawingFigure 2B

AI summary

Methods and systems are described for low latency streaming. A computing device may receive a chunk of content. The computing device may determine whether a transmission duration of the chunk of the content satisfies a threshold. The computing device may determine a bitrate based on the transmission duration satisfying a threshold.