demorse-translation

def goertzel(block_size,samples)
    freq = 500 # from demorse.h AUDIO_FREQ
    s = 0.0
    s_prev1 = 0.0
    s_prev2 = 0.0;

    coeff = 2.0 * Math.cos(2.0 * Math::PI* freq);

    samples.map do |sv|
        s = sv + (coeff * s_prev1) - s_prev2;
        s_prev2 = s_prev1;
        s_prev1 = s;
    end 

    # Normalize over block size
    s_prev1 = s_prev1 / block_size
    s_prev2 = s_prev2 / block_size

    return (s_prev1 * s_prev1) + (s_prev2 * s_prev2)
         - (s_prev1 * s_prev2 * coeff);

end

data = ARGF.read
 keys = %w[id totallength wavefmt format
       pcm channels frequency bytes_per_second
         bytes_by_capture bits_per_sample
           data bytes_in_data sum
 ]
 values = data.unpack 'Z4 i Z8 i s s i i s s Z4 i s*'
 sum = values.drop(12).map(&:abs).inject(:+)
 keys.zip(values.take(12) << sum) {|k, v|
       puts "#{k.ljust 17}: #{v}"
 }

sound_data = values.drop(12)

# Block of frequency over 48 samples
block_size = 20 

freq_blocks = []

sound_data.each_slice(block_size) do |slice|  

  freq_blocks << goertzel(block_size, slice)

end
puts freq_blocks.map{|f| sprintf("%d", f/1000000)}.join("\n")

exit
  up_steps = 0
  down_steps = 0

  freq_blocks.each_with_index do |f, i|
    thresh = 60 # constant
    t1 = f
    t2 = freq_blocks[i+1] || t1 # same if end of input
   unit_elem = 160
   puts "#{t1.inspect}\t #{t2.inspect}"
    if thresh * t1 < 100 * t2
       up_steps = up_steps +1
    elsif 100 * t1 > thresh *t2 
       down_steps = down_steps +1
    end
    if 100 * up_steps > (60 * unit_elem - 1)
         puts "TONE"
    elsif 100 * down_steps > (60 * unit_elem - 1)
	 puts "CLEAR TONE"
    end

  end