1 # -*- coding: utf-8 -*-

2 module WavFile

3

4 class WavFormatError < StandardError

5 end

6

7 class Chunk

8 attr_accessor(:name, :size, :data)

9

10 def initialize(file)

11 @name = file.read(4)

12 @size = file.read(4).unpack("V")[0].to_i

13 @data = file.read(@size)

14 end

15

16 def to_bin

17 @name + [@data.size].pack('V') + @data

18 end

19 end

20

21 class Format

22 attr_accessor(:id, :channel, :hz, :bytePerSec, :blockSize, :bitPerSample)

23

24 def initialize(chunk)

25 return if chunk.class != Chunk

26 return if chunk.name != 'fmt '

27 @id = chunk.data.slice(0,2)[0].to_i

28 @channel = chunk.data.slice(2,2)[0].to_i

29 @hz = chunk.data.slice(4,4).unpack('V').join.to_i

30 @bytePerSec = chunk.data.slice(8,4).unpack('V').join.to_i

31 @blockSize = chunk.data.slice(12,2)[0].to_i

32 @bitPerSample = chunk.data.slice(14,2)[0].to_i

33 end

34

35 def to_s

36 <<EOS

37 フォーマットID: #{@id}

38 チャンネル数: #{@channel}

39 サンプリングレート: #{@hz} (Hz)

40 byte per sec: #{@bytePerSec}

41 bit per sample: #{@bitPerSample}

42 ブロックサイズ: #{blockSize}

43 EOS

44 end

45

46 def to_bin

47 [@id].pack('v')+

48 [@channel].pack('v') +

49 [@hz].pack('V') +

50 [@bytePerSec].pack('V') +

51 [@blockSize].pack('v') +

52 [@bitPerSample].pack('v')

53 end

54

55 def ==(target)

56 @id == target.id &&

57 @channel == target.channel &&

58 @hz == target.hz &&

59 @bytePerSec == target.bytePerSec &&

60 @bitPerSample == target.bitPerSample &&

61 @blockSize == target.blockSize

62 end

63

64 end

65

66 def WavFile.readFormat(f)

67 f.binmode

68 f.seek(0)

69 header = f.read(12)

70 riff = header.slice(0,4)

71 data_size = header.slice(4,4).unpack('V')[0].to_i

72 wave = header.slice(8,4)

73 raise(WavFormatError) if riff != 'RIFF' or wave != 'WAVE'

74

75 formatChunk = Chunk.new(f)

76 Format.new(formatChunk)

77 end

78

79 def WavFile.readAll(f)

80 format = readFormat(f)

81 chunks = Array.new

82 while !f.eof?

83 chunk = Chunk.new(f)

84 chunks << chunk

85 end

86 return format, chunks

87 end

88

89 def WavFile.readDataChunk(f)

90 format, chunks = readAll(f)

91 chunks.each{|c|

92 return c if c.name == 'data'

93 }

94 return nil

95 end

96

97 def WavFile.read(f)

98 return readFormat(f), readDataChunk(f)

99 end

100

101 def WavFile.write(f, format, dataChunks)

102 header_file_size = 4

103 dataChunks.each{|c|

104 header_file_size += c.data.size + 8

105 }

106 f.write('RIFF' + [header_file_size].pack('V') + 'WAVE')

107 f.write("fmt ")

108 f.write([format.to_bin.size].pack('V'))

109 f.write(format.to_bin)

110 dataChunks.each{|c|

111 f.write(c.to_bin)

112 }

113 end

114

115 end