Hybrid Codec Delay Sync for Asymmetric BLE Audio Devices
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Solution Overview
Problem
Existing audio output devices from different OEMs often use different codecs, leading to varying decode processing delays that result in unsynchronized audio output when connected to a host device, impacting the user experience in 3D spatial audio systems.
Innovation Solution
A host device synchronizes audio output by determining the codec decoding delays of multiple connected devices, calculating a compensation delay, and adjusting BLE connections to offset audio data transmission based on the slowest end-to-end codec delay, using the framework of Connected Isochronous Streams within the Isochronous Adaptation Layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different codecs are used for audio transmission to multiple audio output devices, then device compatibility and versatility are improved, but audio synchronization is deteriorated due to varying decode processing delays
Solution Approach 1:
The host device performs preliminary actions by determining the decode processing delay of each audio output device before audio transmission begins. The host device calculates a present compensation delay based on these predetermined delay values and configures the appropriate BLE connection with this compensation delay, enabling synchronized audio output across devices with different codecs.
2Reliability
If codec-specific delay compensation is implemented, then audio synchronization is improved, but system complexity increases due to additional delay determination and calculation procedures
Solution Approach 1:
Each audio output device determines its own decode processing delay and provides this information to the host device. The host device then uses this self-reported delay information to calculate the present compensation delay and configure the BLE connection accordingly, distributing the complexity burden across devices rather than requiring complex centralized control.
3Reliability
If present compensation delay is configured in BLE connection, then audio synchronization is improved, but transmission delay increases due to additional delay compensation mechanisms
Solution Approach 1:
The host device dynamically changes the BLE connection parameter by configuring the present compensation delay based on the specific decode processing delays of the connected audio output devices. This parameter adjustment enables synchronization while minimizing unnecessary delay by tailoring the compensation delay to the actual device characteristics rather than applying a fixed delay.
Data Source
AI summary
Embodiments include methods performed by a host device for syncing Bluetooth Low Energy (BLE) audio, including determining a first codec decoding delay of a first connected audio output device coupled to the host device via a first BLE connection, determining a second codec decoding delay of a second connected audio output device communicatively coupled to the host device via a second BLE connection, determining a difference in decoding delays of the first codec and the second codec, determining a compensation delay as a time difference between the first encoding-decoding delay and the second encoding-decoding delay, configuring one of the first BLE connection or the second BLE connection to include the present compensation delay, and transmitting audio data to the first connected audio output device and the second connected audio output device via the first BLE connection and the second BLE connection.