Audio processing is becoming a key part of several automotive electronic modules, especially in the infotainment arena where more and more consumer applications are demanded to be part of the automotive offering. The move to higher resolution digital audio, combined with new and complex digital signal processing (DSP) algorithms, means 24-bit, fixed-point processors can no longer satisfy the requirements for audio quality, flexibility, and speed. We expect audio requirements to continue growing as high-definition multimedia applications are refined for automotive use.
The quality requirements of in-car audio are lower than those for domestic reproduction, due to the higher background noise of the environment.
However, digital audio is now established in this area via CD and digital radio, which is virtually immune to interference and does not need to be retuned during a journey. MiniDisc and other digital formats can also be incorporated.
Using an Altera Cyclone series FPGA for audio processing include the following benefits:
All audio sources can be processed by the same FPGA, enabling digital
amplification, equalization, and loudspeaker balancing
Fast processing enables useful extra features, such as dynamic range compression
Non-audio sources can also be processed by the same FPGA with its high I/O capability—software defined radio (SDR), global positioning system (GPS), and digital radio text services—to provide a one-chip solution for in-car DSP requirements
Figure 1 shows a conceptual implementation of the next-generation audio processing systems. The combination of the Nios II 32-bit embedded RISC processor with a Cyclone series FPGA provides a high-performance, effective, and flexible solution. The Nios II processor provides the flexibility to implement a coder/decoder (CODEC) with the option of accelerating the compute-intensive portion of the algorithms with custom instructions or with the Nios II C-to-Hardware (C2H) Acceleration Compiler.
Figure 1. Conceptual Implementation of an Audio Processing System in an Altera FPGA
MCU = microcontroller unit
SPI = serial peripheral interface
AAC = advanced audio coding