Wireless Multi-Channel Audio Delivery with Synchronized Playback
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Solution Overview
Problem
Wireless multi-channel audio distribution over packet-based networks faces challenges in achieving high fidelity, low delay, and synchronization, as existing solutions often result in packet loss, delay, and cross-jitter, which affect the quality of audio reproduction and synchronization across speakers.
Innovation Solution
The system employs synchronized playback and network clocks across distributor and sink devices, shuffles audio samples to conceal packet loss, and uses modified multicast signaling to reduce delay, ensuring high fidelity and synchronization by adjusting playback clocks based on timestamps and implementing audio interpolation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packet interleaving is used to combat packet loss, then packet loss is reduced, but delay increases
Solution Approach 1:
The audio stream is divided into packets that are transmitted in a time-division manner across multiple wireless frames. Each packet contains a portion of the audio stream and is transmitted at different times, allowing the receiver to reconstruct the complete audio stream by assembling packets in temporal order. This segmentation enables packet loss recovery without requiring retransmission, thus reducing delay.
Solution Approach 2:
The system performs preliminary actions by transmitting multiple packets in advance across different wireless frames, with each packet containing timing information that allows the receiver to reconstruct the audio stream in the correct temporal order. This preliminary transmission of distributed packets ensures that even if some packets are lost, the audio stream can be reconstructed without waiting for retransmission.
2Reliability
If traditional error correction is used to achieve zero packet loss, then fidelity is improved, but complexity increases
Solution Approach 1:
Instead of using complex error correction codes, the system transmits multiple copies of the audio stream distributed across different wireless frames. Each packet is a copy of a portion of the audio stream, and the receiver assembles these copies in temporal order to reconstruct the complete audio stream. This copying approach achieves high reliability without requiring complex error correction algorithms.
Solution Approach 2:
The audio stream is segmented into multiple packets that are transmitted across different wireless frames. Each packet contains a specific portion of the audio stream with timing information, allowing the receiver to reconstruct the complete stream by assembling segments in temporal order. This segmentation provides a simple and effective alternative to complex error correction.
3Reliability
If synchronization is improved across speakers, then cross-jitter is reduced, but delay increases
Solution Approach 1:
The system uses feedback mechanisms where each packet includes timing information that allows the receiver to adjust its playback clock to match the transmitter's clock. This feedback enables precise synchronization across multiple speakers without requiring excessive delay, as the timing information is embedded within the packets themselves and processed in real-time.
Solution Approach 2:
The system changes the timing parameters by transmitting packets with embedded timing information that allows the receiver to adjust its playback clock frequency and phase to match the transmitter. This parameter adjustment enables precise synchronization across speakers while maintaining low delay, as the timing corrections are applied continuously during playback rather than requiring large initial delays.
Data Source
AI summary
The present disclosure is directed to systems, apparatuses, and methods for wirelessly delivering multi-channel audio over a packet based network with tight synchronization, high fidelity, and/or low delay as described above. The systems can include a source device that provides multi-channel audio to a distributor device, which wirelessly distributes the multi-channel audio over the packet based network to audio rendering devices, referred to as “sink” devices. The distributor device and the sink devices each include a playback clock that is used to read audio samples of the multi-channel audio from a local memory and drive a digital-to-analog converter (DAC) coupled to a speaker to render the audio samples.