Digital Audio Transmission for Mixed PCM and Compressed Streams
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Solution Overview
Problem
Existing digital audio interfaces struggle to simultaneously transmit and reproduce compressed audio signals and linear PCM signals, leading to delays and reduced quality, especially in applications requiring real-time properties, and often require separate audio amplifiers, increasing cost and complexity.
Innovation Solution
A transmission method that combines compressed audio signals and linear PCM signals in a mixed format, using the IEC 60958 standard over coaxial, optical, Ethernet, HDMI, or DisplayPort cables, with added identification and configuration information to enable simultaneous transmission and reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a compressed audio signal is transmitted to an audio amplifier for reproduction, then high-quality reproduction with multiple channels is achieved, but a heavy load is applied in decoding and reproduction inside the television receiver and delay occurs
Solution Approach 1:
The audio signal is segmented into two distinct streams: compressed audio signals (such as MPEG-4 AAC) transmitted in one data field and linear PCM signals transmitted in another data field within the same IEC 60958 protocol frame. This segmentation allows the receiving device to process different signal types independently, enabling real-time response for PCM signals while maintaining high-quality reproduction capability for compressed signals.
Solution Approach 2:
The linear PCM signal is prepared in advance as a ready-to-use real-time audio signal that requires no decoding processing. By pre-converting the real-time audio signal to linear PCM format before transmission, the system eliminates decoding delay for time-critical applications such as game controller responses and artificial intelligence-generated sounds.
2Loss of time
If a linear PCM signal is transmitted for real-time reproduction, then response time is improved, but reproduction quality deteriorates and only low-quality speakers can be used
Solution Approach 1:
The system merges compressed audio signals and linear PCM signals into a single transmission stream using the IEC 60958 protocol. The compressed audio signal carries high-quality audio content for music and video, while the linear PCM signal carries real-time response audio. Both signals are transmitted simultaneously over the same digital audio interface, combining the advantages of both formats without requiring separate physical connections.
3Reliability
If separate audio amplifiers are used for compressed audio signals and linear PCM signals, then simultaneous transmission and reproduction is achieved, but cost increases and device complexity becomes more complicated
Solution Approach 1:
The IEC 60958 digital audio interface is designed to perform multiple functions by accommodating both compressed audio signals and linear PCM signals within the same protocol framework. The transmission device and receiving device are configured to handle both signal types through a single interface, eliminating the need for separate audio amplifiers and reducing system complexity while maintaining the ability to simultaneously reproduce both signal types.
Data Source
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AI summary
The simultaneous transmission and reproduction of a compressed audio signal and a linear PCM signal is satisfactorily achieved. An audio signal of a predetermined unit is sequentially transmitted via a predetermined transmission line to a reception side. The audio signal of the predetermined unit is a mixed signal of a compressed audio signal and a linear PCM signal. For example, the audio signal of the predetermined unit is an audio signal of a sub-frame unit. In this case, for example, in the audio signal of the sub-frame unit, the compressed audio signal is arranged on an upper-order bit side, and the linear PCM signal is arranged on a lower-order bit side.