Audio File Input/Output

• The FileWvIn and FileWvOut classes can be used to read or write data from/to a soundfile.

• Files of type RAW, WAV, AIFF, SND (AU), and MAT (Matlab) containing 8-, 16-, and 32-bit integer, as well as 32- and 64-bit floating-point, data are supported.

• The SineWave class provides sinusoidal oscillator functionality. SineWave's internal table is statically allocated and shared amongst multiple instances of the class.

  // sineosc.cpp STK tutorial program
  
  #include "FileWvOut.h"
  #include "SineWave.h"
  using namespace stk;
  
  int main()
  {
    // Set the global sample rate before creating class instances.
    Stk::setSampleRate( 44100.0 );
    int nFrames = 100000;
  
    SineWave input;
    input.setFrequency( 440.0 );
  
    FileWvOut output;
    try {
      // Open a 16-bit, one-channel WAV formatted output file
      output.openFile( "hellosine.wav", 1, FileWrite::FILE_WAV, Stk::STK_SINT16 );
    }
    catch ( StkError & ) {
      exit(0);
    }
  
    // Single-sample computations
    for ( int i=0; i<nFrames; i++ ) {
      try {
        output.tick( input.tick() );
      }
      catch ( StkError & ) {
        exit( 1 );
      }
    }
  
    return 0;
  }
  

• The classes responsible for soundfile support are FileRead and FileWrite.

• The FileRead and FileWrite classes offer an efficient means for querying audio file parameters because they do not read/write data during instantiation. Further, they never allocate internal memory. Rather, file data is read/written directly to/from a user-provided StkFrames object from/to the file.

• The FileWvIn and FileWvOut classes provide a “tick-level” interface to the FileRead and FileWrite classes.

• FileWvIn provides a variable read rate (including negative rates) using linear interpolation.

• The class FileLoop is a subclass of FileWvIn and provides looping functionality for any of the supported soundfile types mentioned above.

• When opening a file, the FileWvIn class automatically adjusts the data “read” rate based on the current STK sample rate and the file rate. For example, if the sample rate is currently 44100 Hz and the file rate is 22050, the read rate will be set to 0.5. If you need to set an explicit read rate for a given FileWvIn instance, it is safest to change it after the file has been opened.