Represents a node in an audio processing singal graph. There are a handful of basic constructors: node for creating typical audio nodes, keyed for attaching a key or id to an existing node, and ref for referencing a node elsewhere in the graph by id.

There are also a number of constructors for specific audio nodes, such as oscillator and gain. These constructors mirror the low-level nodes provided by the Web Audio API: they make great building blocks!

import WebAudio
import WebAudio.Property


synth : Float -> Float -> List WebAudio.Node -> WebAudio.Node
synth freq gain connections =
    WebAudio.oscillator
        [ WebAudio.Parameters.frequency freq ]
        [ WebAudio.gain
            [ WebAudio.Parameters.gain gain ]
            connections
        ]

The most general way to construct Web Audio nodes. This is used to create all the helper functions below.

You can use this function to define custom nodes by partially applying just the type parameter. This is handy if you're using a library like Tone.js and want to use those nodes in Elm.

import WebAudio
import WebAudio.Property exposing (Property)


omniOscillator : List Property -> List WebAudio.Node -> WebAudio.Node
omniOscillator =
    WebAudio.node "Tone-OmniOscillatorNode"


myOsc : WebAudio.Node
myOsc =
    omniOscillator
        [ WebAudio.Property.frequency 440 ]
        [ WebAudio.dac ]

A ref node is used to refer to some other audio node by id. We can do things like create a feedback loop by connecting a node back into itself.

import WebAudio
import WebAudio.Property exposing (Property)


feedbackDelay : Float -> Float -> List WebAudio.Node -> WebAudio.Node
feedbackDelay amount time connections =
    WebAudio.keyed "feedback-delay" <|
        WebAudio.delay
            [ WebAudio.Property.delayTime time ]
            [ WebAudio.gain
                [ WebAudio.Property.gain gain ]
                -- Reference the delay node above by its key. This sends
                -- the output of the gain node back into the delay node,
                -- creating a feedback loop!
                (WebAudio.ref "feedback-delay" :: connections)
            ]


synth : Float -> Float -> WebAudio.Node
synth freq gain =
    WebAudio.oscillator
        [ WebAudio.Parameters.frequency freq ]
        [ WebAudio.gain
            [ WebAudio.Parameters.gain gain ]
            [ feedbackDelay 0.45 250 <|
                [ WebAudio.dac ]
            ]
        ]

Attach a key or id to an existing node. This is commonly used in conjunction with ref nodes to create feedback loops and other more complex signal graphs.

Typically we chain audio nodes together either implicitly by nesting them or explicitly by using ref nodes but there is a third way to connect audio nodes: by connecting them to certain audio params!

This is useful for common synthesis techniques like AM and FM synthesis, or modulating parameters like cutoff frequencer of a filter using an oscillator.

import WebAudio
import WebAudio.Property


audio : List WebAudio.Node
audio =
    [ WebAudio.oscillator
        [ WebAudio.Property.frequency 5 ]
        -- Connect to the "frequency" parameter of the "carrier" node
        [ WebAudio.param "carrier" "frequency" ]
    , WebAudio.keyed "carrier" <|
        WebAudio.oscillator []
            [ WebAudio.dac ]
    ]

Common properties:

• frequency
• detune
• type

See: https://developer.mozilla.org/en-US/docs/Web/API/OscillatorNode

An alias for oscillator.

It turns out oscillators are pretty common in lots of audio signal graphs. It also turns out that "oscillator" is a pretty long word, so you can use osc instead to save your fingers and your eyes.

Common properties:

• gain

See: https://developer.mozilla.org/en-US/docs/Web/API/GainNode

The audio destination is... the destination of our audio! Connect to this node to get sound coming out of your speakers.

It doesn't have any parameters itself, and it doesn't make sense to connect the destination to anything else; it's the end of the line.

import WebAudio
import WebAudio.Property


audio : List WebAudio.Node
audio =
    [ WebAudio.oscillator
        [ WebAudio.Property.frequency 440 ]
        [ WebAudio.audioDestination ]
    ]

See: https://developer.mozilla.org/en-US/docs/Web/API/AudioDestinationNode

An alias for audioDestination. "dac" is another common name for an output: it stands for digital to analog converter.

Common properties:

• delayTime

See: https://developer.mozilla.org/en-US/docs/Web/API/DelayNode

See: https://developer.mozilla.org/en-US/docs/Web/API/ChannelMergerNode

See: https://developer.mozilla.org/en-US/docs/Web/API/ChanneSplliterNode

Common properties:

• offset

See: https://developer.mozilla.org/en-US/docs/Web/API/ConstantSourceNode

Common properties:

• frequency
• detune
• q
• gain

See: https://developer.mozilla.org/en-US/docs/Web/API/BiquadFilterNode

Common properties:

• buffer
• normalise | normalize

See: https://developer.mozilla.org/en-US/docs/Web/API/ConvolverNode

Common properties:

• threshold
• knee
• ratio
• reduction
• attack
• release

See: https://developer.mozilla.org/en-US/docs/Web/API/DynamicsCompressorNode

See: https://developer.mozilla.org/en-US/docs/Web/API/

Common properties:

• coneInnerAngle
• coneOuterAngle
• coneOuterGain
• distanceModel
• maxDistance
• orientationX
• orientationY
• orientationZ
• panningModel
• positionX
• positionY
• positionZ
• refDistance
• rolloffFactor

See: https://developer.mozilla.org/en-US/docs/Web/API/PannerNode

Common properties:

• pan

See: https://developer.mozilla.org/en-US/docs/Web/API/StereoPannerNode

Common properties:

• curve
• oversample

See: https://developer.mozilla.org/en-US/docs/Web/API/WaveShaperNode

Converts a Node into a value we can through a port to some JavaScript that can actually convert our signal graph into Web Audio code.

You could also go on to seriliase the graph with Json.Encode.encode and send it to a server, store it in LocalStorage, or other fun things.