react-native-audio-api/src/core/AudioBuffer.ts

react-native-audio-api provides system for controlling audio in React Native environment compatible with Web Audio API specification

import { IAudioBuffer } from '../interfaces';
import { IndexSizeError } from '../errors';

export default class AudioBuffer {
  readonly length: number;
  readonly duration: number;
  readonly sampleRate: number;
  readonly numberOfChannels: number;
  /** @internal */
  public readonly buffer: IAudioBuffer;

  constructor(buffer: IAudioBuffer) {
    this.buffer = buffer;
    this.length = buffer.length;
    this.duration = buffer.duration;
    this.sampleRate = buffer.sampleRate;
    this.numberOfChannels = buffer.numberOfChannels;
  }

  public getChannelData(channel: number): Float32Array {
    if (channel < 0 || channel >= this.numberOfChannels) {
      throw new IndexSizeError(
        `The channel number provided (${channel}) is outside the range [0, ${this.numberOfChannels - 1}]`
      );
    }
    return this.buffer.getChannelData(channel);
  }

  public copyFromChannel(
    destination: Float32Array,
    channelNumber: number,
    startInChannel: number = 0
  ): void {
    if (channelNumber < 0 || channelNumber >= this.numberOfChannels) {
      throw new IndexSizeError(
        `The channel number provided (${channelNumber}) is outside the range [0, ${this.numberOfChannels - 1}]`
      );
    }

    if (startInChannel < 0 || startInChannel >= this.length) {
      throw new IndexSizeError(
        `The startInChannel number provided (${startInChannel}) is outside the range [0, ${this.length - 1}]`
      );
    }

    this.buffer.copyFromChannel(destination, channelNumber, startInChannel);
  }

  public copyToChannel(
    source: Float32Array,
    channelNumber: number,
    startInChannel: number = 0
  ): void {
    if (channelNumber < 0 || channelNumber >= this.numberOfChannels) {
      throw new IndexSizeError(
        `The channel number provided (${channelNumber}) is outside the range [0, ${this.numberOfChannels - 1}]`
      );
    }

    if (startInChannel < 0 || startInChannel >= this.length) {
      throw new IndexSizeError(
        `The startInChannel number provided (${startInChannel}) is outside the range [0, ${this.length - 1}]`
      );
    }

    this.buffer.copyToChannel(source, channelNumber, startInChannel);
  }
}