Audio Framework

Overview

The Audio Framework (AF) is a collection of tools and libraries that allow efficient development of audio applications on GAP9 platform. It consists in a collection of tools to create graphs from unitary blocks (components). A high-level input graph file can be designed by one of two front ends:

• CMCore: a Python library that helps generate and manage component descriptions and graphs, as well as the backend used as an interface between the graph instantiation and the rest of the toolchain.

• Graph Designer (GD): A GUI frontend on top of CMCore.

The rest of the Audio Framework consists of the following tools:

• Audio Mapping Tool (AMT): Host tool that takes input graph in .graph (JSON) format and converts it to a fully resolved graph that is fed to Runtime Generator (RTG).

• Runtime Generator (RTG): Host tool that takes fully resolved graph produced by AMT and produces set of source and configuration files that are to be build for GAP9 target.

• Toolchain (TC): A short name for AMT followed by RTG.

• Runtime Library (RNT): Target API that enables user applications to load and run graphs produced by the toolchain.

Graph Designer is the main tool used to design audio graphs, filters and other components using a GUI. To facilitate testing and automation, graphs can also be created written in Python or in C, through the API provided as component library.

The graph process flow of the toolchain is as follows:

• Users can create and tune a graph using the Graph Designer (to use a GUI) or a Genepy script (through Python API)

• The graph is then modified, its contents verified completed from component templates by the Mapping Tool

• The Runtime Generator then compiles that graph into compilable C code, managed by the toolchain.

The audio libraries contain premade components that can be used as building blocks to speed design process of audio graphs, as well as a collection of tools to test and secure those blocks.

Development status

Tool	Status
CMCore	Usable, feature complete
Graph Designer	Usable
Audio Mapping Tool	Usable, incomplete
Runtime Generator	Usable
Runtime library	Usable

Contents

• Examples
  • Adaptive ANC
  • File In File Output
• GAP Audio Framework toolchain
  • Toolchain elements
• GAP Audio Framework tools
  • converters local package
  • Filter design tools
  • Automatic component parameter generator
  • pyfda: a filter design tool
  • Python test tools
  • IIR DF1 biquad cascade
• Matlab Utilities
  • File_io
  • WarpTB
  • biquad_iir_df1_design - Tools to design SFU ready Biquad DF1 filters
  • cic_design - Tools to design SFU ready cic (PDM_Demod) filters
  • fir_design - Tools to design SFU ready FIR filters
  • iir_design - Tools to design SFU ready IIR filters
  • wfir_design - Tools to design SFU ready Warped FIR filters
  • polyphase_design - Tools to design SFU ready polyphase filters

Examples

The examples folder include a number of examples showing how to use the framework. The file_in_out example (examples/applications/file_in_out/) is a basic hello world example for audio, showing how to load construct a simple graph and loading/saving audio from file.

Below is a walktrough of the basic workflow of the framework.

1. Generate a graph

Creating a graph is done by assembling components (a graph’s lowest level unit) into a larger audio topology. This can be done using a CMCore script or (in time) the Graph Designer. Here is an example of a script to create a graph using CMCore:

Such a code will create a graph, recognized by its .graph extension. Each of its fundamental bricks is a component template, located in one of the component libraries. The templates in this library are provided in the GWT component library.

Other examples of CMCore usage can be found in cmcore/examples.

2. Pass the graph to the audio toolchain

python3 -m af_toolchain <my_example_graph>.graph [-o <output_directory>]

Note

Currently, only the mapping tool will run to completion.

Glossary

GD	Graph Designer
AF	Audio Framework
AMT	Audio Mapping Tool
RTG	Runtime Generator
TC	Toolchain (AMT + RTG)
RNT	Runtime library

Audio library

• framework The component-based framework, with components written for the host computer and the target,

• common A collection of various tools:

  • graph parameter generators

  • graph content checkers

  • test helpers and managers

  • conversion utilities: fixed and floating point tools, decibel converters, etc.

• components The collection of components made available in the GWT audio library.

• internal A collection of internal scripts and utilities to manage this repository.

• Audio library common tools and utilities
  • C utilities
  • Unit tests for utilities in common/src
  • Warp Tools
• Components reference
  • Ring Buffer Binding
• Components
  • Structure of a component
  • Developing custom components
  • Other libraries
  • Components reference