esp-libopus

This repository creates an ESP32 component which provides the original Opus code for the ESP32. It includes the original opus library as a submodule.

Usage

This repository can be added as submodule to any valid ESP32 component directory. The easiest way to do this is to create a component/ directory in the root of an ESP project, using git submodule add to clone this repo into there, and to ensure that this new component is recognized via make list-components.

After adding this component to the build configuration, the "opus.h" file can be included. All fixed point Opus decoder and encoder methods are available, consult the Opus documentation for examples.

Demo

To build a demo application with the ESP32, simply:

• Clone this repository
• Open an ESP-IDF console
• cd to ./esp-libopus/example
• Run idf.py build
• Flash the resulting code to your processor and observer.

Important considerations

Opus is a fairly heavy codec, and it might not always work smoothly on the ESP32. The following things have to be taken into account:

• Encoding and Decoding heavily utilize Stack via alloca. It is recommended to have at least 30kB of Stack reserved for the thread that is running the Opus encoding/decoding (the stack is freed after the Opus call, so a single thread can encode and decode).
• Decoding data on the ESP32 is fairly lightweight, even at 48kHz samplerate.
• Encoding however is more intensive. When the ESP32 is clocking at 240MHz, at 48kSps, a mono 16-bit fixed point data stream comprised of random data at encoding complexity 1 will use 48% CPU.

Portability notes

Note: Fixed point is recommended for the ESP32.