Class: Wavesync::AcidChunk

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

Constant Summary collapse

RIFF_HEADER_SIZE =

'RIFF' (4) + size (4) + 'WAVE' (4)

12
CHUNK_ID_SIZE = 
4
CHUNK_SIZE_FIELD_SIZE = 
4
ACID_CHUNK_ID = 
'acid'
ACID_CHUNK_DATA_SIZE = 
24
ACID_TYPE_FLAGS_SIZE = 
4
ACID_ROOT_NOTE_SIZE = 
2
ACID_UNKNOWN1_SIZE = 
2
ACID_UNKNOWN2_SIZE = 
4
ACID_NUM_BEATS_SIZE = 
4
ACID_METER_DENOM_SIZE = 
2
ACID_METER_NUMER_SIZE = 
2
ACID_TEMPO_SIZE = 
4
ACID_TEMPO_OFFSET = 
ACID_TYPE_FLAGS_SIZE +
ACID_ROOT_NOTE_SIZE +
ACID_UNKNOWN1_SIZE +
ACID_UNKNOWN2_SIZE +
ACID_NUM_BEATS_SIZE +
ACID_METER_DENOM_SIZE +
ACID_METER_NUMER_SIZE
UINT32_LITTLE_ENDIAN = 
'V'
FLOAT32_LITTLE_ENDIAN = 
'e'

Class Method Summary collapse

Class Method Details

.create_acid_chunk(output, bpm) ⇒ Object

: (untyped output, Float bpm) -> void



147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
 
# File 'lib/wavesync/acid_chunk.rb', line 147

def self.create_acid_chunk(output, bpm)
  # Write ACID chunk ID
  output.write(ACID_CHUNK_ID)

  # Write chunk size (24 bytes)
  output.write([ACID_CHUNK_DATA_SIZE].pack(UINT32_LITTLE_ENDIAN))

  # Type flags (4 bytes) - 0x01 for one-shot
  output.write([0x01].pack(UINT32_LITTLE_ENDIAN))

  # Root note (2 bytes) - 0x003C (middle C / 60)
  output.write([0x003C].pack('v'))

  # Unknown1 (2 bytes)
  output.write([0x0000].pack('v'))

  # Unknown2 (4 bytes)
  output.write([0x00000000].pack(UINT32_LITTLE_ENDIAN))

  # Number of beats (4 bytes) - 0 for non-loop
  output.write([0x00000000].pack(UINT32_LITTLE_ENDIAN))

  # Meter denominator (2 bytes) - 4 for 4/4 time
  output.write([0x0004].pack('v'))

  # Meter numerator (2 bytes) - 4 for 4/4 time
  output.write([0x0004].pack('v'))

  output.write([bpm].pack(FLOAT32_LITTLE_ENDIAN))
end

.read_bpm(filepath) ⇒ Object

: (String filepath) -> Float?



34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
 
# File 'lib/wavesync/acid_chunk.rb', line 34

def self.read_bpm(filepath)
  Timing.current.measure(:wav_chunks) do
    result = nil #: Float?
    File.open(filepath, 'rb') do |file|
      file.seek(RIFF_HEADER_SIZE)
      until file.eof?
        chunk_id = file.read(CHUNK_ID_SIZE)
        break if chunk_id.nil? || chunk_id.length < CHUNK_ID_SIZE

        chunk_size = ((file.read(CHUNK_SIZE_FIELD_SIZE) || '').unpack1(UINT32_LITTLE_ENDIAN) || 0).to_i
        if chunk_id == ACID_CHUNK_ID
          file.seek(ACID_TEMPO_OFFSET, IO::SEEK_CUR)
          result = ((file.read(ACID_TEMPO_SIZE) || '').unpack1(FLOAT32_LITTLE_ENDIAN) || 0).to_f
          break
        else
          padding = chunk_size.odd? ? 1 : 0
          file.seek(chunk_size + padding, IO::SEEK_CUR)
        end
      end
    end
    result
  end
end

.update_riff_size(filepath) ⇒ Object

: (String filepath) -> void



179
180
181
182
183
184
185
186
187
188
189
 
# File 'lib/wavesync/acid_chunk.rb', line 179

def self.update_riff_size(filepath)
  File.open(filepath, 'r+b') do |file|
    file.seek(0, IO::SEEK_END)
    file_size = file.tell

    riff_size = file_size - 8

    file.seek(4)
    file.write([riff_size].pack(UINT32_LITTLE_ENDIAN))
  end
end

.write_bpm(source_filepath, output_filepath, new_bpm) ⇒ Object

: (String source_filepath, String output_filepath, Integer | Float | String new_bpm) -> void



97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
 
# File 'lib/wavesync/acid_chunk.rb', line 97

def self.write_bpm(source_filepath, output_filepath, new_bpm)
  Timing.current.measure(:wav_chunks) do
    bpm_bytes = [new_bpm.to_f].pack(FLOAT32_LITTLE_ENDIAN)
    acid_chunk_found = false

    File.open(source_filepath, 'rb') do |input|
      File.open(output_filepath, 'wb') do |output|
        riff_header = input.read(RIFF_HEADER_SIZE)
        output.write(riff_header)

        until input.eof?
          chunk_id = input.read(CHUNK_ID_SIZE)
          break if chunk_id.nil? || chunk_id.length < CHUNK_ID_SIZE

          chunk_size_bytes = input.read(CHUNK_SIZE_FIELD_SIZE) || ''
          chunk_size = (chunk_size_bytes.unpack1(UINT32_LITTLE_ENDIAN) || 0).to_i

          output.write(chunk_id)
          output.write(chunk_size_bytes)

          if chunk_id == ACID_CHUNK_ID
            acid_chunk_found = true

            output.write(input.read(ACID_TEMPO_OFFSET))

            input.read(ACID_TEMPO_SIZE)

            output.write(bpm_bytes)

            remaining = chunk_size - ACID_TEMPO_OFFSET - ACID_TEMPO_SIZE
            output.write(input.read(remaining)) if remaining.positive?

            output.write(input.read(1)) if chunk_size.odd?
          else
            padding = chunk_size.odd? ? 1 : 0
            output.write(input.read(chunk_size + padding))
          end
        end

        create_acid_chunk(output, new_bpm.to_f) unless acid_chunk_found
      end
    end

    next if acid_chunk_found

    update_riff_size(output_filepath)
  end
end

.write_bpm_in_place(filepath, new_bpm) ⇒ Object

: (String filepath, Integer | Float | String new_bpm) -> void



59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
 
# File 'lib/wavesync/acid_chunk.rb', line 59

def self.write_bpm_in_place(filepath, new_bpm)
  Timing.current.measure(:wav_chunks) do
    bpm_bytes = [new_bpm.to_f].pack(FLOAT32_LITTLE_ENDIAN)

    File.open(filepath, 'r+b') do |file|
      file.seek(RIFF_HEADER_SIZE)

      acid_chunk_found = false

      until file.eof?
        chunk_id = file.read(CHUNK_ID_SIZE)
        break if chunk_id.nil? || chunk_id.length < CHUNK_ID_SIZE

        chunk_size_bytes = file.read(CHUNK_SIZE_FIELD_SIZE) || ''
        chunk_size = (chunk_size_bytes.unpack1(UINT32_LITTLE_ENDIAN) || 0).to_i

        if chunk_id == ACID_CHUNK_ID
          file.seek(ACID_TEMPO_OFFSET, IO::SEEK_CUR)
          file.write(bpm_bytes)
          acid_chunk_found = true
          break
        else
          padding = chunk_size.odd? ? 1 : 0
          file.seek(chunk_size + padding, IO::SEEK_CUR)
        end
      end

      unless acid_chunk_found
        file.seek(0, IO::SEEK_END)
        create_acid_chunk(file, new_bpm.to_f)
      end
    end

    update_riff_size(filepath)
  end
end