constructor()

in 9-realtime/openai-realtime-console-example/src/lib/wavtools/lib/analysis/audio_analysis.js [94:157]

• 63 lines of code
• 6 McCabe index (conditional complexity)

  constructor(audioElement, audioBuffer = null) {
    this.fftResults = [];
    if (audioBuffer) {
      /**
       * Modified from
       * https://stackoverflow.com/questions/75063715/using-the-web-audio-api-to-analyze-a-song-without-playing
       *
       * We do this to populate FFT values for the audio if provided an `audioBuffer`
       * The reason to do this is that Safari fails when using `createMediaElementSource`
       * This has a non-zero RAM cost so we only opt-in to run it on Safari, Chrome is better
       */
      const { length, sampleRate } = audioBuffer;
      const offlineAudioContext = new OfflineAudioContext({
        length,
        sampleRate,
      });
      const source = offlineAudioContext.createBufferSource();
      source.buffer = audioBuffer;
      const analyser = offlineAudioContext.createAnalyser();
      analyser.fftSize = 8192;
      analyser.smoothingTimeConstant = 0.1;
      source.connect(analyser);
      // limit is :: 128 / sampleRate;
      // but we just want 60fps - cuts ~1s from 6MB to 1MB of RAM
      const renderQuantumInSeconds = 1 / 60;
      const durationInSeconds = length / sampleRate;
      const analyze = (index) => {
        const suspendTime = renderQuantumInSeconds * index;
        if (suspendTime < durationInSeconds) {
          offlineAudioContext.suspend(suspendTime).then(() => {
            const fftResult = new Float32Array(analyser.frequencyBinCount);
            analyser.getFloatFrequencyData(fftResult);
            this.fftResults.push(fftResult);
            analyze(index + 1);
          });
        }
        if (index === 1) {
          offlineAudioContext.startRendering();
        } else {
          offlineAudioContext.resume();
        }
      };
      source.start(0);
      analyze(1);
      this.audio = audioElement;
      this.context = offlineAudioContext;
      this.analyser = analyser;
      this.sampleRate = sampleRate;
      this.audioBuffer = audioBuffer;
    } else {
      const audioContext = new AudioContext();
      const track = audioContext.createMediaElementSource(audioElement);
      const analyser = audioContext.createAnalyser();
      analyser.fftSize = 8192;
      analyser.smoothingTimeConstant = 0.1;
      track.connect(analyser);
      analyser.connect(audioContext.destination);
      this.audio = audioElement;
      this.context = audioContext;
      this.analyser = analyser;
      this.sampleRate = this.context.sampleRate;
      this.audioBuffer = null;
    }
  }