Add global DC-Filter and remove all individual DC-Filters
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@@ -30,30 +30,26 @@
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* audio level calculation
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*/
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/* return average value (rectified value), that can be 0..1 */
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/* Return average value (rectified value)
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* The input must not have any dc offset!
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* For a perfect rectangualr wave, the result would equal the peak level.
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* For a sine wave the result would be factor (2 / PI) below peak level.
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*/
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double audio_level(sample_t *samples, int length)
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{
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double bias;
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double level;
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int sk;
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double level, sk;
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int n;
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/* calculate bias */
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bias = 0;
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for (n = 0; n < length; n++)
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bias += samples[n];
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bias = bias / length;
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/* level calculation */
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level = 0;
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for (n = 0; n < length; n++) {
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sk = samples[n] - bias;
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sk = samples[n];
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if (sk < 0)
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level -= (double)sk;
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if (sk > 0)
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level += (double)sk;
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}
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level = level / (double)length / 32767.0;
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level = level / (double)length;
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return level;
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}
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@@ -79,17 +75,10 @@ void audio_goertzel_init(goertzel_t *goertzel, double freq, int samplerate)
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*/
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void audio_goertzel(goertzel_t *goertzel, sample_t *samples, int length, int offset, double *result, int k)
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{
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double bias;
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double sk, sk1, sk2;
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double cos2pik;
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int i, n;
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/* calculate bias to remove DC */
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bias = 0;
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for (n = 0; n < length; n++)
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bias += samples[n];
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bias = bias / length;
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/* we do goertzel */
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for (i = 0; i < k; i++) {
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sk = 0;
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@@ -98,7 +87,7 @@ void audio_goertzel(goertzel_t *goertzel, sample_t *samples, int length, int off
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cos2pik = goertzel[i].coeff;
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/* note: after 'length' cycles, offset is restored to its initial value */
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for (n = 0; n < length; n++) {
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sk = (cos2pik * sk1) - sk2 + samples[offset++] - bias;
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sk = (cos2pik * sk1) - sk2 + samples[offset++];
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sk2 = sk1;
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sk1 = sk;
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if (offset == length)
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