Project architecture overview

The core of this project is an audio pipeline separated into 3 parts:

- Fetching samples -> Processing (applying settings and effects) -> Outputting modified samples

Above this pipeline exists a GUI which interacts with the Processing by changing its settings and visualizing its outputs.

Fetching stage

IAudioReader

Reads actual data from the audio file.

Exposes metadata about the file - sample rate and channel count.

IAudioStream

Is created upon successful decoding of an audio file and creates an abstraction for the input. Can be consumed by calling ReadFrame(int size) at a desired pace.

Makes sure that all samples are in a set size of frames.

It also enforces the IDisposable contract and is therefore intended to cease to exist when the connected audio stops playing or is aborted.

Audio Processing

Audio Engine

The core class of the processing stage. Runs the entire pipeline.

Is created with the AudioStream and shares its lifespan with it.

Runs processes that consume data from a stream and add it to a player in parallel.

Uses and IFftProcessor to decompose sound and extract information about frequencies.

From there it exports to the IFreqDataReceiver if necessary.

Applies all plugin effects, volume changes, eq settings to the audio samples.

Processed samples get sent to the IAudioPlayer.

Output stage

IAudioPlayer

Receives samples from the audio engine and buffers them in order to output them at a steady pace.

Must be fed enough samples to prevent skips or distortion.

GUI

UIController

Runs the GUI logic and makes calls to the AudioEngine based on requests from Views.

FreqViewDataProcessor

Implements the IFreqDataReceiver interface and accepts data from the AudioEngine.

It further processes this data so that the desired Views can render it straight away.

FreqGraphView

Draws the current state of the frequency graph every couple of miliseconds.

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Plugins

Plugins get instantiated from a set folder via reflection thanks to the IAudioPlugin interface.

The 3rd party developer has access to normalized PCM samples and can edit them freely.

Role of external libraries

1. NAudio
   • Used on Windows for decoding audio files in IAudioReader and playing PCM samples in IAudioPlayer.
2. Math.NET
   • IFftProcessor wraps around its Fourier transform to create frame-sized transformations.
3. Terminal.Gui
   • Takes care of the GUI part of the project, manages windows and input registering. Allows for graph drawing.

Further possible expansions

The project is laid out in such a way that making it work cross-platform should be straightforward and painless.

Readers/Players are abstracted behind an interface. Linux/macOS support could work by just adding some more dependecies that decode audio files and connect to audio sinks.