Live Broadcast Audio Synchronization Using Cross-Correlation
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Solution Overview
Problem
Existing technologies face challenges in synchronizing audio streams for live broadcasts due to latency discrepancies between live audio sources and streaming platforms, particularly in dynamic environments with noise and varying distances from the sound source, leading to a jarring listening experience.
Innovation Solution
A system and method using cross-correlation analysis to estimate the relative delay between audio signals captured by a microphone and streamed audio, employing techniques like cross-correlation, average square difference, peak analysis, and generalized cross-correlation with phase transformation, optimized for real-world conditions with noise and single microphone setups, to synchronize audio streams with a known baseline latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cross-correlation analysis is used to estimate delay between audio signals, then time delay estimation accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent divides the audio signal into multiple frames and performs cross-correlation analysis on each frame separately. This segmentation allows the system to estimate time delay continuously across different time periods while managing computational load by processing smaller segments rather than the entire signal at once.
Solution Approach 2:
The patent performs preliminary cross-correlation analysis on received audio frames to estimate time delay before playing back the supplemental audio stream. This preliminary estimation allows the system to pre-calculate the necessary delay adjustment, ensuring synchronized playback without real-time computational burden during the actual audio output.
2Reliability
If audio streams are synchronized with known baseline latency, then listening experience is improved, but system complexity increases
Solution Approach 1:
The patent introduces a reference audio signal as an intermediary between the supplemental audio stream and the live broadcast audio. By comparing the supplemental audio against this reference signal with known baseline latency, the system can calculate the appropriate delay adjustment without directly comparing multiple complex audio streams, thereby simplifying the synchronization process.
Solution Approach 2:
The patent implements a feedback mechanism where the estimated time delay from cross-correlation analysis is used to adjust the playback timing of the supplemental audio stream. This closed-loop approach continuously monitors the synchronization status and makes real-time adjustments, improving listening experience while managing system complexity through automated control.
Data Source
AI summary
Systems and methods for playing synchronized audio streams for live broadcasts are described. For example, supplemental audio streams (e.g., extra commentary or sound effects) may be streamed over a packet switched network with a copy (e.g., a reduced bandwidth copy) of a main audio signal from a television broadcast. A user device may synchronize the streamed audio with the audio from a television recorded with a microphone, and play a supplemental audio signal synchronously with the audio from the television. For example, methods may include capturing a first audio signal using a microphone; receiving a second audio signal and a third audio signal using a network interface; determining an estimated delay of the first audio signal relative to the second audio signal; and playing, using a speaker, the third audio signal with an added delay determined based on the estimated delay.