Digital Clock Circuit for Video Audio Synchronization
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Solution Overview
Problem
Conventional video/audio data transmission over networks often results in synchronization issues due to the variability of crystal and silicon component operating characteristics with voltage and temperature changes, leading to unsynchronized video and audio data, which can cause lip-sync problems and jittery video playback.
Innovation Solution
A digital clock circuit is generated using timing information from a precise timing protocol message, allowing for the creation of a digital clock with specific frequency and phase, which is used to control the processing of video/audio data, reducing the need for crystals and other components and improving synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crystal-based rendering clock is used to generate timing signals, then the clock can provide a stable frequency, but the operating characteristics of the crystal and silicon components change with voltage and temperature variations, causing frequency drift and loss of synchronization
Solution Approach 1:
The patent replaces the mechanical crystal oscillator system with a digital clock generation system that uses a phase-locked loop (PLL) to generate timing signals from a reference clock. This substitution eliminates the frequency drift issues inherent in crystal oscillators while maintaining stable timing generation, directly resolving the contradiction between reliability and environmental sensitivity.
Solution Approach 2:
The patent implements a phase-locked loop (PLL) mechanism that continuously monitors and adjusts the phase and frequency of the generated clock signal to match the reference clock. This feedback control ensures that the rendering clock remains synchronized even when environmental conditions change, resolving the contradiction by maintaining stability through active correction rather than passive component characteristics.
2Productivity
If conventional crystal-based clocks are used in rendering devices, then timing signals can be generated, but voltage and temperature variations cause frequency changes that result in unsynchronized video and audio data
Solution Approach 1:
The patent replaces the crystal-based timing generation with a digital PLL-based clock generation system. This substitution provides more accurate and stable timing signals for frame rendering, eliminating the frequency variations that cause synchronization errors between video and audio, thus improving both productivity and timing precision.
Solution Approach 2:
The patent changes the fundamental parameter of clock generation from passive crystal oscillation to active digital PLL-controlled frequency synthesis. This parameter change allows the system to maintain precise timing accuracy across varying voltage and temperature conditions, ensuring accurate frame rendering and synchronization without the drift problems of conventional crystals.
3Loss of information
If frames are time stamped using a studio clock, then the frames can be processed in a specific order, but the rendering clock frequency changes due to component characteristic variations, causing the frames to be rendered at incorrect times
Solution Approach 1:
The patent uses a phase-locked loop to continuously compare the rendering clock with the studio clock reference and adjust the rendering clock frequency to match. This feedback mechanism ensures that frames are rendered at the correct times according to their time stamps, maintaining both sequence integrity and timing accuracy despite environmental variations.
Solution Approach 2:
The patent replaces the unreliable crystal-based rendering clock with a digitally controlled clock system that uses PLL technology. This substitution enables the system to accurately follow the time stamps on frames and render them at the correct times, preserving frame sequence integrity while achieving reliable timing accuracy that is immune to component characteristic variations.
Data Source
AI summary
Systems, methods, and other embodiments associated with clock generation are provided. In one embodiment, an apparatus comprises a digital clock circuit. Receive logic is configured to receive a timing message from a network device, where the timing message includes timing information associated with a stream of content. Content logic is configured to process the stream of content. A frequency and a phase are determined from the timing information. The digital clock circuit is configured to generate a digital clock with the frequency and the phase, where the digital clock is used to control the content logic to process the stream of content.