Audio Stream Timestamp Control for Wireless Sample Rate Sync
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Solution Overview
Problem
Current audio streaming systems face challenges in synchronizing the sampling rate of audio sources and sinks, leading to buffer overflow or underflow, which results in audio artifacts and distortions, particularly in binaural systems where image shift and psycho-acoustic effects occur due to varying device delays.
Innovation Solution
A time-stamp based controller is implemented to adjust the sampling rate of electronic devices, using arrival and departure time-stamps to calculate an adjustment stimulus for the sample rate actuator, ensuring synchronization with external packet rates and maintaining constant device delay, thereby preventing buffer overflow or underflow and audio distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sampling rate of audio sources and sinks is not synchronized, then the system operates independently without complex synchronization mechanisms, but buffer overflow or underflow occurs leading to audio artifacts and distortions
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the device delay by comparing arrival timestamps and departure timestamps, calculates the actual sampling rate, and generates adjustment stimuli to correct deviations from the target sampling rate. This closed-loop feedback system ensures reliable synchronization while maintaining manageable complexity through automated error correction.
Solution Approach 2:
The system performs self-adjustment by automatically calculating device delay, determining sampling rate deviations, and generating correction signals without external intervention. The controller autonomously maintains synchronization by continuously adjusting the sampling rate based on real-time performance measurements, eliminating the need for complex manual synchronization protocols.
2Reliability
If device delay varies in binaural systems, then the system structure remains simple, but image shift and psycho-acoustic effects occur due to unsynchronized audio streams
Solution Approach 1:
The controller measures device delay by comparing timestamps and uses this feedback to adjust the sampling rate in both audio sinks, ensuring synchronized playback. This feedback-driven approach maintains consistent device delay across binaural systems, preventing image shift and psycho-acoustic effects while keeping the control mechanism manageable through automated adjustment.
Solution Approach 2:
The system aims to equalize device delay across both audio sinks by adjusting their sampling rates to match the target rate. By maintaining equivalent timing conditions in both channels, the system prevents desynchronization artifacts while using a relatively simple timestamp-based measurement and adjustment mechanism.
3Measurement precision
If timestamp-based control is implemented to maintain high accuracy device delay, then synchronization precision improves to within 10 microseconds, but the complexity of timestamp processing and calculation increases
Solution Approach 1:
The system achieves high measurement precision through automated timestamp processing where the controller independently reads timestamps, calculates device delay, determines sampling rate deviations, and generates adjustment stimuli without external intervention. This self-service approach maintains 10 microsecond accuracy while managing processing complexity through a unified automated control algorithm.
Data Source
AI summary
Disclosed herein, among other things, are methods and apparatus for providing a time-stamp based controller for synchronization of sink or source sampling rate with external packet rate. A method for wireless communications includes receiving a transmission of a packet using a wireless transceiver of an electronic device, and using a processor of the electronic device to read a first value of a system timer and store the first value as an arrival time-stamp. The packet is decoded and processed by the processor, and sent to an output. When the processed packet is sent, a second value of the system timer is read, adjusted and stored as a departure time-stamp. The arrival time-stamp and the departure time-stamp are used to calculate an adjustment stimulus for a sample rate actuator of the electronic device. The sample rate actuator is configured to maintain synchronization of sampling rate with an external packet rate.