Struct AnalyserNode

pub struct AnalyserNode { /* private fields */ }

AnalyserNode represents a node able to provide real-time frequency and time-domain analysis information.

It is an AudioNode that passes the audio stream unchanged from the input to the output, but allows you to take the generated data, process it, and create audio visualizations..

• MDN documentation: https://developer.mozilla.org/en-US/docs/Web/API/AnalyserNode
• specification: https://webaudio.github.io/web-audio-api/#AnalyserNode
• see also: BaseAudioContext::create_analyser

Usage

use web_audio_api::context::{BaseAudioContext, AudioContext};
use web_audio_api::node::{AudioNode, AudioScheduledSourceNode};

let context = AudioContext::default();

let mut analyser = context.create_analyser();
analyser.connect(&context.destination());

let mut osc = context.create_oscillator();
osc.frequency().set_value(200.);
osc.connect(&analyser);
osc.start();

let mut bins = vec![0.; analyser.frequency_bin_count()];


loop {
    analyser.get_float_frequency_data(&mut bins);
    println!("{:?}", &bins[0..20]); // print 20 first bins
    std::thread::sleep(std::time::Duration::from_millis(1000));
}

Examples

• cargo run --release --example analyser
• cd showcase/mic_playback && cargo run --release

Implementations

impl AnalyserNode

pub fn new<C: BaseAudioContext>(context: &C, options: AnalyserOptions) -> Self

pub fn fft_size(&self) -> usize

The size of the FFT used for frequency-domain analysis (in sample-frames)

Panics

This method may panic if the lock to the inner analyser is poisoned

pub fn set_fft_size(&mut self, fft_size: usize)

Set FFT size

Panics

This function panics if fft_size is not a power of two or not in the range [32, 32768]

pub fn smoothing_time_constant(&self) -> f64

Time averaging parameter with the last analysis frame. A value from 0 -> 1 where 0 represents no time averaging with the last analysis frame. The default value is 0.8.

Panics

This method may panic if the lock to the inner analyser is poisoned

pub fn set_smoothing_time_constant(&mut self, value: f64)

Set smoothing time constant

Panics

This function panics if the value is set to a value less than 0 or more than 1.

pub fn min_decibels(&self) -> f64

Minimum power value in the scaling range for the FFT analysis data for conversion to unsigned byte values. The default value is -100.

Panics

This method may panic if the lock to the inner analyser is poisoned

pub fn set_min_decibels(&mut self, value: f64)

Set min decibels

Panics

This function panics if the value is set to a value more than or equal to max decibels.

pub fn max_decibels(&self) -> f64

Maximum power value in the scaling range for the FFT analysis data for conversion to unsigned byte values. The default value is -30.

Panics

This method may panic if the lock to the inner analyser is poisoned

pub fn set_max_decibels(&mut self, value: f64)

Set max decibels

Panics

This function panics if the value is set to a value less than or equal to min decibels.

pub fn frequency_bin_count(&self) -> usize

Number of bins in the FFT results, is half the FFT size

Panics

This method may panic if the lock to the inner analyser is poisoned

pub fn get_float_time_domain_data(&mut self, buffer: &mut [f32])

Copy the current time domain data as f32 values into the provided buffer

Panics

This method may panic if the lock to the inner analyser is poisoned

pub fn get_byte_time_domain_data(&mut self, buffer: &mut [u8])

Copy the current time domain data as u8 values into the provided buffer

Panics

This method may panic if the lock to the inner analyser is poisoned

pub fn get_float_frequency_data(&mut self, buffer: &mut [f32])

Copy the current frequency data into the provided buffer

Panics

This method may panic if the lock to the inner analyser is poisoned

pub fn get_byte_frequency_data(&mut self, buffer: &mut [u8])

Copy the current frequency data scaled between min_decibels and max_decibels into the provided buffer

Panics

This method may panic if the lock to the inner analyser is poisoned

Trait Implementations

impl AudioNode for AnalyserNode

fn registration(&self) -> &AudioContextRegistration

Handle of the associated BaseAudioContext.

fn channel_config(&self) -> &ChannelConfig

Config for up/down-mixing of input channels for this node.

fn number_of_inputs(&self) -> usize

The number of inputs feeding into the AudioNode. For source nodes, this will be 0.

fn number_of_outputs(&self) -> usize

The number of outputs coming out of the AudioNode.

fn context(&self) -> &ConcreteBaseAudioContext

The BaseAudioContext concrete type which owns this AudioNode.

fn connect<'a>(&self, dest: &'a dyn AudioNode) -> &'a dyn AudioNode

Connect the output of this AudioNode to the input of another node.

fn connect_from_output_to_input<'a>( &self, dest: &'a dyn AudioNode, output: usize, input: usize, ) -> &'a dyn AudioNode

Connect a specific output of this AudioNode to a specific input of another node.

fn disconnect(&self)

Disconnects all outgoing connections from the AudioNode.

fn disconnect_dest(&self, dest: &dyn AudioNode)

Disconnects all outputs of the AudioNode that go to a specific destination AudioNode.

fn disconnect_output(&self, output: usize)

Disconnects all outgoing connections at the given output port from the AudioNode.

fn disconnect_dest_from_output(&self, dest: &dyn AudioNode, output: usize)

Disconnects a specific output of the AudioNode to a specific destination AudioNode

fn disconnect_dest_from_output_to_input( &self, dest: &dyn AudioNode, output: usize, input: usize, )

Disconnects a specific output of the AudioNode to a specific input of some destination AudioNode

fn channel_count_mode(&self) -> ChannelCountMode

Represents an enumerated value describing the way channels must be matched between the node’s inputs and outputs.

fn set_channel_count_mode(&self, v: ChannelCountMode)

Update the channel_count_mode attribute

fn channel_interpretation(&self) -> ChannelInterpretation

Represents an enumerated value describing the meaning of the channels. This interpretation will define how audio up-mixing and down-mixing will happen.

fn set_channel_interpretation(&self, v: ChannelInterpretation)

Update the channel_interpretation attribute

fn channel_count(&self) -> usize

Represents an integer used to determine how many channels are used when up-mixing and down-mixing connections to any inputs to the node.

fn set_channel_count(&self, v: usize)

Update the channel_count attribute

fn set_onprocessorerror( &self, callback: Box<dyn FnOnce(ErrorEvent) + Send + 'static>, )

Register callback to run when an unhandled exception occurs in the audio processor.

fn clear_onprocessorerror(&self)

Unset the callback to run when an unhandled exception occurs in the audio processor.

impl Debug for AnalyserNode

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.