Class: AudioFingerprint::Fingerprint

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

Constant Summary collapse

BITS_PER_RAW_ITEM = 
32
THRESHOLD = 
0.85

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(file) ⇒ Fingerprint

Returns a new instance of Fingerprint.



19
20
21
22
 
# File 'lib/audio_fingerprint/fingerprint.rb', line 19

def initialize(file)
	@fingerprint = []
	@file = file
end

Instance Attribute Details

#file ⇒ Object

Returns the value of attribute file.



17
18
19
 
# File 'lib/audio_fingerprint/fingerprint.rb', line 17

def file
  @file
end

#fingerprint ⇒ Object

Returns the value of attribute fingerprint.



16
17
18
 
# File 'lib/audio_fingerprint/fingerprint.rb', line 16

def fingerprint
  @fingerprint
end

Instance Method Details

#compare(fp) ⇒ Object 



44
45
46
47
48
49
50
51
52
53
54
55
56
57
 
# File 'lib/audio_fingerprint/fingerprint.rb', line 44

def compare(fp)
	max_raw_size = [@fingerprint.size, fp.size].max
	bit_size     = max_raw_size * BITS_PER_RAW_ITEM

	distance     = hamming_distance(@fingerprint, fp)

	match 		 = 1 - distance.to_f / bit_size

	if match >= THRESHOLD
		match
	else
		false
	end
end

#create_fingerprint ⇒ Object 



24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
 
# File 'lib/audio_fingerprint/fingerprint.rb', line 24

def create_fingerprint
	w    		 = AudioFingerprint::WaveFile.open(@file)
	samples  	 = w.sample_data[0, [w.sample_rate * 10, w.sample_data.size].min]
	duration 	 = samples.size / w.sample_rate
	na 			 = NArray.float(2, samples.size)
	@fingerprint ||= []
	
	samples.each_with_index do |v, i|
		na[0, i - 1] = i.to_f / w.sample_rate.to_f
		na[1, i - 1] = v
	end

	fa = FFTW3.fft(na)
	fa = fa.real.abs

	fa.each do |f|
		@fingerprint << f
	end
end