Audio Stream Sampling Rate Control for Wireless Packet Sync
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Solution Overview
Problem
Existing wireless communication systems, particularly in hearing assistance devices, face challenges in synchronizing the sampling rate of audio streams with external packet rates, leading to buffer overflow or underflow, and resulting in audio artifacts and distortions.
Innovation Solution
The implementation of a time-stamp based controller that adjusts the sample rate of electronic devices to maintain synchronization with external packet rates, using arrival and departure time-stamps to calculate an adjustment stimulus for the sample rate actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sampling rate is adjusted to match external packet rate, then synchronization is improved, but device complexity increases due to time-stamp based control mechanisms
Solution Approach 1:
The patent implements a feedback control system where arrival time-stamps and departure time-stamps are used to calculate an adjustment stimulus that is fed back to the sample rate actuator. This closed-loop feedback mechanism automatically adjusts the sampling rate to maintain synchronization with the external packet rate, resolving the contradiction by using systematic feedback rather than complex manual control.
Solution Approach 2:
The patent introduces time-stamps as an intermediary element that mediates between the external packet rate and the internal sampling rate. The arrival time-stamp and departure time-stamp serve as intermediate measurements that enable the calculation of adjustment stimulus, simplifying the control mechanism while maintaining reliable synchronization.
2Object-affected harmful factors
If sampling rate synchronization is implemented, then audio artifacts are prevented, but loss of time increases due to timestamp calculation and processing
Solution Approach 1:
The patent applies preliminary action by recording the arrival time-stamp immediately when a packet is received, before any processing occurs. This early timestamp capture eliminates the need for retrospective timing calculations, reducing processing time while still preventing audio artifacts through accurate synchronization control.
3Measurement precision
If device delay is maintained constant through sampling rate adjustment, then synchronization precision is improved, but productivity decreases due to continuous rate adjustment
Solution Approach 1:
The patent implements dynamic sampling rate adjustment where the sample rate actuator continuously adapts the sampling rate based on real-time synchronization requirements. This dynamic approach maintains constant device delay with high precision (variations close to 10 microseconds) while optimizing throughput by only adjusting the rate when necessary, rather than using fixed conservative rates.
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.