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Cardboard VR Projects for Android by Matt Schoen, Jonathan Linowes

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Capturing audio data

Using the Android Visualizer class (http://developer.android.com/reference/android/media/audiofx/Visualizer.html), we can retrieve part of the audio data that is currently playing, at a specified sample rate. You can choose to capture data as waveform and/or frequency data:

  • Waveform: This is an array of mono audio waveform bytes, or pulse code modulation (PCM) data, representing a sample series of audio amplitudes
  • Frequency: This is an array of Fast Fourier Transform (FFT) bytes, representing a sampling of audio frequencies

The data is limited to 8 bits, so it's not useful for playback but is sufficient for visualizations. You can specify the sampling rate, although it must be a power of two.

Armed with this knowledge, we'll now ...

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