chathhorn / simple-wave

Simple MS Wave file parser.

This is an MS Wave file parser intended for pedagogical purposes.

Chris Hathhorn (Fall 2011)

wave.h

This file provides an API with limited support for reading and writing MS Wave (.wav) files. See the "Wave" class below for details.

The Wave class public interface

      /*** Public Data ***/
      // These objects represent the contents of this Wave file.
      RiffChunk riff_chunk;
      FmtChunk fmt_chunk;
      DataChunk data_chunk;

      // There are various other chunk types beyond those specifically
      // supported by this class. Any chunk that's not a RIFF, fmt, or
      // data chunk gets stuck here in this vector. They're represented
      // by more DataChunk objects. So a DataChunk might be the actual
      // "data" section of the file or other unrecognized sections of the
      // file. 
      std::vector<DataChunk> other_chunks;

      /*** Constructors ***/
      Wave(void) { };

      /*** Public Methods ***/
      // Load and save the Wave file. Load fails if the file doesn't
      // exist, Save will create a new file or overwrite an existing
      // file.
      void Load(std::string const& filename);
      void LoadMetadata(std::string const& filename);
      void Save(std::string const& filename);

      // Resize the data chunk to support a certain number of samples.
      // The new size of the data chunk depends on the values set in the
      // format chunk.
      void Resize(unsigned new_nsamples);

      // Get & set sample values at certain offsets, where offset <
      // nsamples(). Both fail silently if the offset is out-of-bounds.
      double GetSample(unsigned offset) const;
      void SetSample(unsigned offset, double value);

      // Gets the number of samples in the data chunk.
      unsigned nsamples(void) const;

      // Print diagnostic info about this Wave file.
      friend std::ostream& operator<<(std::ostream& stream, Wave const& wave);

Example usage:

     Wave wave;
     wave.Load(filename);

     // Set various header values.
     wave.fmt_chunk.nchannels = 1;
     wave.fmt_chunk.block_align = 2;
     wave.fmt_chunk.bits_per_sample = 16;

     // Resize the data chunk.
     unsigned nsamples = 10000;
     wave.Resize(nsamples);

     // Set various sample values in the data chunk.
     for (unsigned i = 0; i != nsamples; ++i) {
           wave.SetSample(i, my_sample_value[i]);
     }

     wave.Save(filename);

wave.cpp

This file contains various example Wave-file manipulation functions using the wave.h API with a simple, interactive user interface.

Example functions:

• faster -- Speed it up by dropping every other sample.
• slower -- Slow it down by duplicating every other sample.
• echo -- Create an echo effect by adding samples back in after a delay.
• amp_up -- Increase the volume (amplitude) by 20%.
• amp_down -- Decrease the volume (amplitude) by 20%.
• reverse -- Reverse.
• mix -- Mix two WAVs together. The new file should be as long as the longest operand file. The shorter file gets looped.