Audiovisual Synchronization Measurement in Video Encoders
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Solution Overview
Problem
Current methods for measuring audiovisual synchronization in digital video encoding and decoding systems are inadequate, as they often require offline testing, manual intervention, and cannot accurately isolate synchronization errors within the encoding process, especially when the system is online and geographically separated.
Innovation Solution
A method and apparatus that measure the input times of audio and video data into encoders and calculate the audiovisual synchronization value by determining the difference between presentation and input times, which can be transmitted within the MPEG-2 Transport Stream to downstream components for automatic alignment, allowing for continuous monitoring and correction without the need for a separate decoder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offline testing with separate decoders is used to measure audiovisual synchronization, then measurement capability is achieved, but system complexity increases and real-time monitoring is lost
Solution Approach 1:
The patent merges the synchronization measurement function into the encoder itself by adding a measurement unit that captures input time information directly at the encoding stage. This eliminates the need for separate test decoders and offline testing, as the encoder now performs both encoding and synchronization measurement functions simultaneously.
Solution Approach 2:
The encoder performs self-measurement of audiovisual synchronization by incorporating a measurement unit that automatically captures input time information for both audio and video streams during the encoding process. This self-service approach eliminates the need for external measurement equipment and manual intervention.
2Measurement precision
If manual intervention is used for synchronization measurement, then measurement can be performed, but productivity decreases and real-time correction is impossible
Solution Approach 1:
The patent implements automatic feedback by having the measurement unit continuously monitor input time information during encoding and generate synchronization status information that is fed back to the system. This enables real-time detection of synchronization issues without manual intervention and allows for immediate corrective action.
Solution Approach 2:
The measurement unit operates continuously during the encoding process, constantly capturing input time information and monitoring synchronization status. This continuous measurement approach replaces intermittent manual testing, ensuring real-time detection and enabling ongoing productivity without interruption.
3Adaptability or versatility
If geographically separated encoders are used, then system versatility is improved, but synchronization alignment becomes difficult to maintain
Solution Approach 1:
The patent introduces an intermediary mechanism in the form of time reference information that is embedded in the encoded bitstream. This intermediary carries synchronization data that allows geographically separated encoders to maintain alignment by referencing common time standards, thus preserving reliability despite geographic distribution.
Solution Approach 2:
The measurement unit performs preliminary measurement of input time information during the encoding process itself, before the encoded streams are transmitted from geographically separated locations. This preliminary capture of timing data establishes a common reference framework that maintains synchronization alignment across distributed encoders.
4Device complexity
If encoder-specific delays are not isolated, then measurement simplicity is maintained, but measurement precision deteriorates due to mixed synchronization errors
Solution Approach 1:
The patent segments the synchronization measurement into distinct components by separately measuring input time information for audio and video streams independently at the encoder input stage. This segmentation allows for precise isolation of encoder-specific delays for each stream type, distinguishing them from other synchronization errors that may occur later in the system.
Data Source
AI summary
There is provided a method of measuring audiovisual synchronization between at least one encoded audio stream and at least one encoded video stream, comprising measuring the time of input into an audio encoder of source audio data to be encoded into said encoded audio stream, measuring the time of input into a video encoder of source video data to be encoded into said encoded video stream, determining a Presentation Time Stamp value, indicative of a time of presentation, for each of the respective at least one encoded audio stream and at least one encoded video stream, and transmitting a measured audio input time, a measured video input time and presentation time stamp values to a downstream component. There is also provided an apparatus and system for measuring audiovisual synchronization between at least one encoded audio stream and at least one encoded video stream.