Audio digital effects with DSP pre-processing and graphic interface

Abstract

This projet was focused on developing a new kind of audio platform that combined digital audio processing, block-based programming, and streaming technologies. It utilized a Raspberry Pi along with the ADAU1701 DSP chip, running a Linux-based operating system called Volumio, which played high-fidelity audio from local servers, streaming service apps and radio shows in real-time. The project leveraged the I2C protocol for communication between SigmaStudio and the ADAU1701, enabling configuration and control of the DSP chip. Meanwhile, the I2S protocol was used for high-quality audio data transfer between the Raspberry Pi and the ADAU1701, allowing for low-latency streaming of audio signals. An audio plugin was created in SigmaStudio using block-based programming. While connected to the same intranet and streaming an audio file via DLNA/UPnP to the Raspberry Pi, it was possible to modify the audio signal. Users could adjust parameters using analog potentiometers and control audio playback through a smartphone app or by accessing the “volumio.local” URL. Additionally, visual feedback of the digitized input signal was provided via a touch-sensitive LCD screen, allowing instant control of the Volumio OS. The plugin featured a 3-band digital equalizer using a combination of shelving and peak filters, enabling control over low, mid, and high frequencies, as well as the overall output volume of the audio signal. Tests were conducted to analyze the signaling behavior and the response of the filters, confirming the effectiveness of the audio chain system. In summary, the project demonstrated the feasibility of an audio platform that offered significant functionalities for both casual listeners and professionals, integrating advanced audio processing, a user-friendly experience, and a cost-effective yet powerful solution that could be easily customized and expanded.