Class: AudioWaveform::WaveformDataFile

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

Overview

Provides access to audio waveform data, and serialization to and from binary and JSON data formats.

Instance Method Summary collapse

Constructor Details

#initialize(args) ⇒ WaveformDataFile

Returns a new instance of WaveformDataFile.

Parameters:

  • args (Hash)

Options Hash (args):

  • :filename (String) —

    Loads the specified binary waveform data file.

  • :sample_rate (Integer)
  • :samples_per_pixel (Integer)
  • :bits (Integer)
  • :start_time (Numeric, nil) —

    Start time, in seconds, or nil if no start time to be set.



21
22
23
24
25
26
27
28
29
30
31
32
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 21

def initialize(args)
  if args[:filename]
    read(args[:filename])
  else
    self.sample_rate       = args[:sample_rate]
    self.samples_per_pixel = args[:samples_per_pixel]
    self.bits              = args[:bits]
    self.start_time        = args[:start_time]

    @data = []
  end
end

Instance Method Details

#append(min_sample, max_sample) ⇒ WaveformDataFile

Appends a waveform minimum/maximum pair.

Parameters:

  • min_sample (Integer) —

    Minimum audio sample amplitude value.

  • max_sample (Integer) —

    Maximum audio sample amplitude value.

Returns:



185
186
187
188
189
190
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 185

def append(min_sample, max_sample)
  @data << min_sample
  @data << max_sample

  self
end

#bits ⇒ Integer

Returns Resolution of waveform data points, either 8 or 16 bits.

Returns:

  • (Integer) —

    Resolution of waveform data points, either 8 or 16 bits.



73
74
75
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 73

def bits
  @bits
end

#bits=(bits) ⇒ Object

Sets the resolution of waveform data points.

Parameters:

  • bits (Integer) —

    Number of bits, must be either 8 or 16 bits



81
82
83
84
85
86
87
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 81

def bits=(bits)
  if bits != 8 && bits != 16
    raise Error, "Invalid bits: #{bits}"
  else
    @bits = bits
  end
end

#max_sample(index) ⇒ Integer

Returns The maximum waveform data point at the specified index.

Returns:

  • (Integer) —

    The maximum waveform data point at the specified index.



200
201
202
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 200

def max_sample(index)
  @data[2 * index + 1]
end

#min_sample(index) ⇒ Integer

Returns The minimum waveform data point at the specified index.

Returns:

  • (Integer) —

    The minimum waveform data point at the specified index.



194
195
196
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 194

def min_sample(index)
  @data[2 * index]
end

#sample_rate ⇒ Integer

Returns Audio sample rate, in Hz.

Returns:

  • (Integer) —

    Audio sample rate, in Hz.



36
37
38
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 36

def sample_rate
  @sample_rate
end

#sample_rate=(sample_rate) ⇒ Object

Parameters:

  • sample_rate (Integer) —

    Audio sample rate, in Hz. Must be greater than zero.



43
44
45
46
47
48
49
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 43

def sample_rate=(sample_rate)
  if sample_rate <= 0
    raise Error, "Invalid sample rate: #{sample_rate}"
  else
    @sample_rate = sample_rate
  end
end

#samples_per_pixel ⇒ Integer

Returns Number of audio samples per waveform minimum/maximum pair.

Returns:

  • (Integer) —

    Number of audio samples per waveform minimum/maximum pair.



54
55
56
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 54

def samples_per_pixel
  @samples_per_pixel
end

#samples_per_pixel=(samples_per_pixel) ⇒ Object

Sets the waveform data scaling.

Parameters:

  • samples_per_pixel (Integer) —

    Number of audio samples per waveform minimum/maximum pair.



63
64
65
66
67
68
69
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 63

def samples_per_pixel=(samples_per_pixel)
  if samples_per_pixel <= 0
    raise Error, "Invalid samples per pixel: #{samples_per_pixel}"
  else
    @samples_per_pixel = samples_per_pixel
  end
end

#save_as_binary(filename) ⇒ WaveformDataFile

Writes the waveform data to file in binary (.dat) format.

Parameters:

  • filename (String) —

    The name of the file to write.

Returns:



130
131
132
133
134
135
136
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 130

def save_as_binary(filename)
  File.open(filename, "wb") do |file|
    file.write(to_binary)
  end

  self
end

#save_as_json(filename) ⇒ WaveformDataFile

Writes the waveform data to file in JSON format.

Parameters:

  • filename (String) —

    The name of the file to write.

Returns:



117
118
119
120
121
122
123
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 117

def save_as_json(filename)
  File.open(filename, "w") do |file|
    file.write(to_json)
  end

  self
end

#size ⇒ Integer

Returns Length of waveform data (number of minimum/maximum value pairs).

Returns:

  • (Integer) —

    Length of waveform data (number of minimum/maximum value pairs).



207
208
209
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 207

def size
  @data.size / 2
end

#start_time ⇒ Numeric?

Returns Start time of the waveform data, in seconds, or nil if not set.

Returns:

  • (Numeric, nil) —

    Start time of the waveform data, in seconds, or nil if not set.



92
93
94
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 92

def start_time
  @start_time
end

#start_time=(start_time) ⇒ Object

Sets the start time of the waveform data.

Parameters:

  • start_time (Numeric, nil) —

    Start time of the waveform data, in seconds, or nil if none.



102
103
104
105
106
107
108
109
110
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 102

def start_time=(start_time)
  if start_time.nil?
    @start_time = nil
  elsif start_time < 0
    raise Error, "Invalid start time: #{start_time}"
  else
    @start_time = start_time
  end
end

#to_binary ⇒ String

Returns A binary representation of the waveform data file.

Returns:

  • (String) —

    A binary representation of the waveform data file.



164
165
166
167
168
169
170
171
172
173
174
175
176
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 164

def to_binary
  if @bits == 8
    flags  = FLAG_8_BIT
    format = "c*"
  else
    flags  = 0
    format = "s*"
  end

  output = encode_header(1, flags, @sample_rate, @samples_per_pixel, size)
  output += @data.pack(format)
  output
end

#to_hash ⇒ Hash

Returns A hash representation of the waveform data file.

Returns:

  • (Hash) —

    A hash representation of the waveform data file.



140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 140

def to_hash
  obj = {
    sample_rate:       @sample_rate,
    bits:              @bits,
    samples_per_pixel: @samples_per_pixel,
    length:            @data.size / 2,
    data:              @data
  }

  if @start_time
    obj[:start_time] = @start_time
  end

  obj
end

#to_json ⇒ String

Returns A JSON representation of the waveform data file.

Returns:

  • (String) —

    A JSON representation of the waveform data file.



158
159
160
 
# File 'lib/audio_waveform/waveform_data_file.rb', line 158

def to_json
  JSON.generate(to_hash)
end