Class: WaveInfo

Inherits:
Object
  • Object
show all
Defined in:
lib/waveinfo.rb

Defined Under Namespace

Classes: FileFormatError

Instance Method Summary collapse

Constructor Details

#initialize(file) ⇒ WaveInfo

Create a new WaveInfo object to get information and metadata about a Wave file (.wav). ‘file’ can either be a filename or an IO object.



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# File 'lib/waveinfo.rb', line 7

def initialize(file)

  # Set default values
  @audio_format_id = 0
  @bits_per_sample = nil
  @block_align = nil
  @byte_rate = nil
  @channels = nil
  @data_size = nil
  @sample_rate = nil
  @samples = nil
  
  # What was passed in to us?
  if file.is_a?(String)
    @io = File.new(file, 'rb')
    @filepath = @io.path
    read_headers
    @io.close
  else
    @io = file
    @filepath = @io.path
    read_headers
  end
end

Instance Method Details

#audio_format ⇒ Object

Get the name of the audio codec (for example ‘PCM’).



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# File 'lib/waveinfo.rb', line 43

def audio_format
  case @audio_format_id
    when 0x01 then
      "PCM"
    when 0x02 then
      "Microsoft ADPCM"
    when 0x06 then
      "a-law"
    when 0x07 then
      "u-law"
    when 0x11 then
      "IMA ADPCM"
    when 0x14 then
      "G.723"
    when 0x31 then
      "GSM"
    when 0x40 then
      "G.721"
    when 0x50 then
      "MPEG-1 Audio"
    when 0x55 then
      "MPEG Audio Layer 3"
    else
      "Unknown (#{@audio_format_id})"
  end
end

#audio_format_id ⇒ Object

Get the identifier of the audio codec (for example PCM would be 1).



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# File 'lib/waveinfo.rb', line 38

def audio_format_id
  @audio_format_id
end

#bits_per_sample ⇒ Object

Get the number of bits per sample.



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# File 'lib/waveinfo.rb', line 91

def bits_per_sample
  @bits_per_sample
end

#block_align ⇒ Object

Get the number of bytes per sample slice.



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# File 'lib/waveinfo.rb', line 86

def block_align
  @block_align
end

#byte_rate ⇒ Object

Get the average number of bytes per second.



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# File 'lib/waveinfo.rb', line 81

def byte_rate
  @byte_rate
end

#channels ⇒ Object

Get the number of channels.



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# File 'lib/waveinfo.rb', line 71

def channels
  @channels
end

#duration ⇒ Object

Get the duration of the audio (in seconds).



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# File 'lib/waveinfo.rb', line 110

def duration
  samples.to_f / sample_rate.to_f
end

#filename ⇒ Object

Return the name of the input file.



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# File 'lib/waveinfo.rb', line 33

def filename
  File.basename(@filepath)
end

#sample_rate ⇒ Object

Get the sample rate (in Hz).



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# File 'lib/waveinfo.rb', line 76

def sample_rate
  @sample_rate
end

#samples ⇒ Object

Get the total number of samples.



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# File 'lib/waveinfo.rb', line 96

def samples
  if @samples
    @samples
  else
    @data_size / @block_align
  end
end

#size ⇒ Object

Get the length of the audio data (in bytes).



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# File 'lib/waveinfo.rb', line 105

def size
  @data_size
end