Class: Feep::SoundFile
- Inherits:
-
Object
- Object
- Feep::SoundFile
- Defined in:
- lib/feep/sound_file.rb
Instance Method Summary collapse
- #create_sound(frequency, samples, output_filename, options) ⇒ Object
- #generate_sample_data(wave_type, num_samples, frequency, max_amplitude) ⇒ Object
Instance Method Details
#create_sound(frequency, samples, output_filename, options) ⇒ Object
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# File 'lib/feep/sound_file.rb', line 11 def create_sound(frequency, samples, output_filename, ) # Generate sample data for the given frequency, amplitude, and duration. # Since we are using a sample rate of 44,100Hz, 44,100 samples are required for one second of sound. samples = generate_sample_data([:waveform].to_sym, samples, frequency.to_f, [:volume].to_f) # Wrap the array of samples in a Buffer, so that it can be written to a Wave file # by the WaveFile gem. Since we generated samples between -1.0 and 1.0, the sample # type should be :float buffer = WaveFile::Buffer.new(samples, WaveFile::Format.new(:mono, :float, 44100)) # Write the Buffer containing our samples to a 16-bit, monophonic Wave file # with a sample rate of 44,100Hz, using the WaveFile gem. WaveFile::Writer.new(output_filename, WaveFile::Format.new(:mono, :pcm_16, 44100)) do |writer| writer.write(buffer) end end |
#generate_sample_data(wave_type, num_samples, frequency, max_amplitude) ⇒ Object
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# File 'lib/feep/sound_file.rb', line 28 def generate_sample_data(wave_type, num_samples, frequency, max_amplitude) position_in_period = 0.0 position_in_period_delta = frequency / SAMPLE_RATE # Initialize an array of samples set to 0.0. Each sample will be replaced with # an actual value below. samples = [].fill(0.0, 0, num_samples) num_samples.times do |i| # Add next sample to sample list. The sample value is determined by # plugging position_in_period into the appropriate wave function. if wave_type == :sine samples[i] = Math::sin(position_in_period * TWO_PI) * max_amplitude elsif wave_type == :square samples[i] = (position_in_period >= 0.5) ? max_amplitude : -max_amplitude elsif wave_type == :saw samples[i] = ((position_in_period * 2.0) - 1.0) * max_amplitude elsif wave_type == :triangle samples[i] = max_amplitude - (((position_in_period * 2.0) - 1.0) * max_amplitude * 2.0).abs elsif wave_type == :noise samples[i] = RANDOM_GENERATOR.rand(-max_amplitude..max_amplitude) end position_in_period += position_in_period_delta # Constrain the period between 0.0 and 1.0. # That is, keep looping and re-looping over the same period. if(position_in_period >= 1.0) position_in_period -= 1.0 end end return samples end |