Audio Signal Time Alignment via Coarse and Fine Functions
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Solution Overview
Problem
Existing methods for aligning audio recordings from different sources, such as close microphones and video camera microphones, face challenges due to synchronization issues caused by clock frequency differences and environmental factors, leading to misalignment and poor audio quality in video recordings.
Innovation Solution
A system and method for time-aligning audio signals using a combination of coarse and fine alignment functions, which includes a coarse alignment function to reduce initial misalignment and a fine alignment function to determine a precise time shift between signals, allowing for accurate synchronization of audio recordings from different sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If audio signals are recorded using microphones positioned close to the sound source, then audio quality is improved by reducing environmental noise, but synchronization with video recording becomes more difficult due to lack of integrated timing mechanisms
Solution Approach 1:
The patent introduces an intermediary mechanism (audio-video synchronization system) that mediates between separately recorded audio and video signals. This system uses timing metadata and correlation algorithms to bridge the gap between independent recording devices, enabling precise synchronization without requiring physical integration or SMPTE timecode infrastructure.
Solution Approach 2:
The patent replaces mechanical/sync-based synchronization systems (cable runs, wireless links, SMPTE timecode) with a computational approach using correlation algorithms and timing metadata. This substitution eliminates the need for complex physical synchronization infrastructure while achieving reliable audio-video alignment.
2Reliability
If manual alignment methods are used to synchronize audio and video recordings, then initial synchronization can be achieved, but time drift between recordings causes progressive misalignment during playback
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors timing metadata and correlation between audio-video signals throughout playback. This feedback system dynamically adjusts for time drift by detecting deviations from the optimal alignment and compensating in real-time, maintaining synchronization stability over extended playback durations.
Solution Approach 2:
The patent performs preliminary analysis of timing metadata and signal correlation during the alignment process to predict and pre-compensate for potential time drift. By analyzing clock frequency differences and recording conditions beforehand, the system establishes correction parameters that prevent misalignment before it occurs during playback.
3Productivity
If coarse alignment methods are used to quickly synchronize audio signals, then processing time is reduced, but precision of alignment deteriorates leading to residual misalignment
Solution Approach 1:
The patent segments the alignment process into multiple stages: coarse alignment using timing metadata for rapid initial synchronization, followed by fine alignment using correlation algorithms for precision adjustment. This segmentation allows the system to achieve both high productivity (through quick coarse alignment) and high precision (through detailed fine alignment) without requiring exhaustive processing at every stage.
Data Source
AI summary
Systems and methods for time-aligning a first and second media signals. The first and second media signals may be audio signals recorded for combining as one audio performance or as an audio portion of an audio-video recording. The system retrieves the audio signals as digital samples generated using a common sampling rate. The system includes at least one coarse alignment function for reducing an initial misalignment between the first and second signal. The coarse alignment function may be configured to generate a coarse-shifted second signal. A fine alignment function determines an aligning time shift between the coarse-shifted second signal and the first signal by performing a cross-correlation between the first signal and the coarse-shifted second signal.