In-band A/V Timing Measurement via VANC Fingerprinting
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Solution Overview
Problem
Existing systems face challenges in synchronizing audio and video signals without requiring the television facility to be out of service, often necessitating expensive equipment and bi-directional communication for resynchronization.
Innovation Solution
The system uses in-band signaling to encode characterization data in the vertical ancillary (VANC) space of HDTV signals, allowing receivers to measure and resynchronize audio and video signals by comparing extracted and recomputed data, eliminating the need for the facility to be out of service and reducing hardware complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional characterization techniques are used to measure relative offset, then the relative offset can be determined, but the television facility must be out of service
Solution Approach 1:
The system embeds characterization data (fingerprints) into the video and audio signals in advance at the television facility before transmission. This preliminary encoding allows receivers to perform offset measurements without requiring the facility to be out of service, as the measurement references are already embedded in the transmitted signals.
Solution Approach 2:
The receiver autonomously extracts the embedded characterization data from received signals, recomputes expected values, and determines the relative offset independently without requiring facility intervention. The system uses itself (the transmitted signals) to provide the measurement references needed for synchronization.
2Productivity
If techniques that do not require the television facility to be out of service are used, then facility operation continues, but expensive equipment and bi-directional communication are required
Solution Approach 1:
The system uses embedded characterization data (fingerprints) as an intermediary carrier that conveys timing reference information within the existing unidirectional broadcast signal. This eliminates the need for expensive bi-directional communication equipment while maintaining the ability to measure and correct synchronization offsets.
Solution Approach 2:
The television facility creates simplified copies (fingerprints) of the video and audio signal characteristics and embeds them in the transmission. These fingerprint copies are sufficient for offset measurement purposes, replacing the need for complex measurement equipment at the receiver end.
3Productivity
If in-band signaling is used to encode characterization data in VANC space, then dynamic synchronization is enabled without facility disruption, but the VANC space must accommodate additional data
Solution Approach 1:
The system extracts only the essential timing characterization information (fingerprints) from the full video and audio signals and embeds only these condensed representations in the VANC space. This extraction approach minimizes the data burden on VANC space while retaining sufficient information for accurate offset measurement and dynamic synchronization.
Data Source
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AI summary
A system and method for characterizing the relative offset in time between audio and video signals and enables the receiver of the audio and video signals to resynchronize the audio and video signals. Signal characterization data is dynamically captured and encoded into frames of video and audio data that is output by a television origination facility. The signal characterization data is extracted by the receiver and signal characterization data is recomputed for the received frames. The extracted signal characterization data is compared with the recomputed signal characterization data to compute the relative offset in time between the video and one or more audio signals for a frame. The receiver may then resynchronize the video and audio signals using the computed relative offset.