Improved handling of audio subsystem delays

Measurer.h

@@ -3,6 +3,8 @@
 
 #include <QAudioDeviceInfo>
 
+#include "fft.h"
+
 enum MeasureChannel
 {
 	Left,
@@ -11,15 +13,24 @@ enum MeasureChannel
 
 class Measurer
 {
+	// frequency for generating tone
 	const int TONE_FREQUENCY = 6000;
+	// frequency window width to search for resulting tone 
+	const int FREQUENCY_GAP = 100;
+	// our resulting amplitude should differ at least this times from average
+	// to be considered as measured signal
+	const float PEAK_LEVEL = 1.0;
+	//
 	const int SAMPLE_RATE = 44100;
 	const float SILENCE_LEVEL = 0.3;
+	const float INITIAL_DELAY_PERCENTAGE = 0.3;
 
 	MeasureChannel channel;
 	QAudioDeviceInfo input, output;
 	bool debug;
 
 	float ProcessData(QByteArray data);
+	float ProcessSpectrum(int pow, Complex* d);
 public:
 	Measurer(QAudioDeviceInfo input, QAudioDeviceInfo output, MeasureChannel channel, bool debug);
 	float Measure(float duration);