audio_analyzer.c File Reference

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <math.h>
#include "qa_tools.h"
#include "audio_analyzer.h"
#include "write_wav.h"

Macros
#define	PAQA_POP_THRESHOLD   (0.04)
#define	NUM_SAMPLES   (200)
#define	MAX_BUFFER_SIZE   2048

Functions
double	PaQa_GetNthFrequency (double baseFrequency, int index)
void	PaQa_EraseBuffer (float *buffer, int numFrames, int samplesPerFrame)
void	PaQa_SetupSineGenerator (PaQaSineGenerator *generator, double frequency, double amplitude, double frameRate)
void	PaQa_MixSine (PaQaSineGenerator *generator, float *buffer, int numSamples, int stride)
void	PaQa_GenerateCrackDISABLED (float *buffer, int numSamples, int stride)
int	PaQa_InitializeRecording (PaQaRecording *recording, int maxFrames, int frameRate)
void	PaQa_TerminateRecording (PaQaRecording *recording)
int	PaQa_WriteRecording (PaQaRecording *recording, float *buffer, int numFrames, int stride)
int	PaQa_WriteSilence (PaQaRecording *recording, int numFrames)
int	PaQa_RecordFreeze (PaQaRecording *recording, int numFrames)
int	PaQa_SaveRecordingToWaveFile (PaQaRecording *recording, const char *filename)
double	PaQa_MeasureCrossingSlope (float *buffer, int numFrames)
double	PaQa_MeasureSineAmplitudeBySlope (PaQaRecording *recording, double frequency, double frameRate, int startFrame, int numFrames)
double	PaQa_CorrelateSine (PaQaRecording *recording, double frequency, double frameRate, int startFrame, int numFrames, double *phasePtr)
void	PaQa_FilterRecording (PaQaRecording *input, PaQaRecording *output, BiquadFilter *filter)
double	PaQa_FindFirstMatch (PaQaRecording *recording, float *buffer, int numFrames, double threshold)
double	PaQa_MeasureArea (float *buffer, int numFrames, int stride)
double	PaQa_MeasureRootMeanSquare (float *buffer, int numFrames)
double	PaQa_CompareAmplitudes (PaQaRecording *recording, int startAt, float *buffer, int numFrames)
double	PaQa_ComputePhaseDifference (double phase1, double phase2)
int	PaQa_MeasureLatency (PaQaRecording *recording, PaQaTestTone *testTone, PaQaAnalysisResult *analysisResult)
void	PaQa_FadeInRecording (PaQaRecording *recording, int startFrame, int count)
int	PaQa_DetectPop (PaQaRecording *recording, PaQaTestTone *testTone, PaQaAnalysisResult *analysisResult)
int	PaQa_DetectPhaseError (PaQaRecording *recording, PaQaTestTone *testTone, PaQaAnalysisResult *analysisResult)
int	PaQa_AnalyseRecording (PaQaRecording *recording, PaQaTestTone *testTone, PaQaAnalysisResult *analysisResult)

Macro Definition Documentation

#define MAX_BUFFER_SIZE   2048

Referenced by PaQa_MeasureLatency().

#define NUM_SAMPLES   (200)

Referenced by PaQa_SaveRecordingToWaveFile().

#define PAQA_POP_THRESHOLD   (0.04)

Referenced by PaQa_DetectPop().

Function Documentation

int PaQa_AnalyseRecording	(	PaQaRecording *	recording,
		PaQaTestTone *	testTone,
		PaQaAnalysisResult *	analysisResult
	)

Analyse a recording of a sine wave. Measure latency and look for dropped frames, etc.

References PaQaAnalysisResult_s::amplitudeRatio, PaQaAnalysisResult_s::latency, PaQa_DetectPhaseError(), PaQa_DetectPop(), PaQa_MeasureLatency(), QA_ASSERT_EQUALS, and PaQaAnalysisResult_s::valid.

double PaQa_CompareAmplitudes	(	PaQaRecording *	recording,
		int	startAt,
		float *	buffer,
		int	numSamples
	)

Compare the amplitudes of these two signals. Return ratio of recorded signal over buffer signal.

References PaQaRecording_s::buffer, PaQaRecording_s::numFrames, PaQa_MeasureArea(), and QA_ASSERT_TRUE.

Referenced by PaQa_MeasureLatency().

double PaQa_ComputePhaseDifference	(	double	phase1,
		double	phase2
	)

References MATH_PI, and MATH_TWO_PI.

Referenced by PaQa_DetectPhaseError().

double PaQa_CorrelateSine	(	PaQaRecording *	recording,
		double	frequency,
		double	frameRate,
		int	startFrame,
		int	numFrames,
		double *	phasePtr
	)

References PaQaRecording_s::buffer, MATH_PI, MATH_TWO_PI, PaQaRecording_s::numFrames, and QA_ASSERT_TRUE.

Referenced by PaQa_CheckForLoopBack(), and PaQa_DetectPhaseError().

int PaQa_DetectPhaseError	(	PaQaRecording *	recording,
		PaQaTestTone *	testTone,
		PaQaAnalysisResult *	analysisResult
	)

References PaQaAnalysisResult_s::addedFramesPosition, PaQaAnalysisResult_s::droppedFramesPosition, PaQaTestTone_s::frequency, PaQaAnalysisResult_s::latency, MATH_TWO_PI, PaQaAnalysisResult_s::numAddedFrames, PaQaAnalysisResult_s::numDroppedFrames, PaQaRecording_s::numFrames, PaQa_ComputePhaseDifference(), PaQa_CorrelateSine(), and PaQaTestTone_s::sampleRate.

Referenced by PaQa_AnalyseRecording().

int PaQa_DetectPop	(	PaQaRecording *	recording,
		PaQaTestTone *	testTone,
		PaQaAnalysisResult *	analysisResult
	)

Apply notch filter and high pass filter then detect remaining energy.

References BiquadFilter_SetupHighPass(), BiquadFilter_SetupNotch(), PaQaRecording_s::buffer, PaQaTestTone_s::frequency, PaQaAnalysisResult_s::latency, PaQaRecording_s::numFrames, PaQa_FadeInRecording(), PaQa_FilterRecording(), PaQa_InitializeRecording(), PAQA_POP_THRESHOLD, PaQa_TerminateRecording(), PaQaAnalysisResult_s::popAmplitude, PaQaAnalysisResult_s::popPosition, QA_ASSERT_EQUALS, and PaQaRecording_s::sampleRate.

Referenced by PaQa_AnalyseRecording().

void PaQa_EraseBuffer	(	float *	buffer,
		int	numFrames,
		int	samplesPerFrame
	)

Referenced by PaQa_FillWithSine(), and PaQa_MeasureLatency().

void PaQa_FadeInRecording	(	PaQaRecording *	recording,
		int	startFrame,
		int	count
	)

References PaQaRecording_s::buffer, and MATH_PI.

Referenced by PaQa_DetectPop().

void PaQa_FilterRecording	(	PaQaRecording *	input,
		PaQaRecording *	output,
		BiquadFilter *	filter
	)

Apply a biquad filter to the audio from the input recording and write it to the output recording.

References BiquadFilter_Filter(), PaQaRecording_s::buffer, PaQaRecording_s::maxFrames, and PaQaRecording_s::numFrames.

Referenced by PaQa_DetectPop().

double PaQa_FindFirstMatch	(	PaQaRecording *	recording,
		float *	buffer,
		int	numFrames,
		double	threshold
	)

Scan until we get a correlation of a single that goes over the tolerance level, peaks then drops to half the peak. Look for inverse correlation as well.

References PaQaRecording_s::buffer, PaQaRecording_s::numFrames, and QA_ASSERT_TRUE.

Referenced by PaQa_MeasureLatency().

void PaQa_GenerateCrackDISABLED	(	float *	buffer,
		int	numSamples,
		int	stride
	)

References MATH_TWO_PI.

double PaQa_GetNthFrequency	(	double	baseFrequency,
		int	index
	)

Calculate Nth frequency of a series for use in testing multiple channels. Series should avoid harmonic overlap between channels.

int PaQa_InitializeRecording	(	PaQaRecording *	recording,
		int	maxSamples,
		int	sampleRate
	)

Allocate memory for containing a mono audio signal. Set up recording for writing.

References PaQaRecording_s::buffer, PaQaRecording_s::maxFrames, PaQaRecording_s::numFrames, QA_ASSERT_TRUE, and PaQaRecording_s::sampleRate.

Referenced by PaQa_DetectPop().

double PaQa_MeasureArea	(	float *	buffer,
		int	numFrames,
		int	stride
	)

Measure the area under the curve by summing absolute value of each value.

Referenced by PaQa_CompareAmplitudes().

double PaQa_MeasureCrossingSlope	(	float *	buffer,
		int	numFrames
	)

Measure slope of the positive zero crossings.

Referenced by PaQa_MeasureSineAmplitudeBySlope().

int PaQa_MeasureLatency	(	PaQaRecording *	recording,
		PaQaTestTone *	testTone,
		PaQaAnalysisResult *	analysisResult
	)

References PaQaTestTone_s::amplitude, PaQaAnalysisResult_s::amplitudeRatio, buffer, PaQaTestTone_s::frequency, PaQaAnalysisResult_s::latency, MAX_BUFFER_SIZE, PaQa_CompareAmplitudes(), PaQa_EraseBuffer(), PaQa_FindFirstMatch(), PaQa_MixSine(), PaQa_SetupSineGenerator(), QA_ASSERT_TRUE, PaQaTestTone_s::sampleRate, PaQaTestTone_s::samplesPerFrame, and PaQaAnalysisResult_s::valid.

Referenced by PaQa_AnalyseRecording().

double PaQa_MeasureRootMeanSquare	(	float *	buffer,
		int	numFrames
	)

Referenced by PaQa_MeasureBackgroundNoise().

double PaQa_MeasureSineAmplitudeBySlope	(	PaQaRecording *	recording,
		double	frequency,
		double	frameRate,
		int	startFrame,
		int	numFrames
	)

Estimate the original amplitude of a clipped sine wave by measuring its average slope at the zero crossings.

References buffer, PaQaRecording_s::buffer, MATH_TWO_PI, and PaQa_MeasureCrossingSlope().

Referenced by PaQa_CheckForClippedLoopback().

void PaQa_MixSine	(	PaQaSineGenerator *	generator,
		float *	buffer,
		int	numSamples,
		int	stride
	)

References PaQaSineGenerator_s::amplitude, MATH_TWO_PI, PaQaSineGenerator_s::phase, and PaQaSineGenerator_s::phaseIncrement.

Referenced by PaQa_FillWithSine(), and PaQa_MeasureLatency().

int PaQa_RecordFreeze	(	PaQaRecording *	recording,
		int	numFrames
	)

References PaQaRecording_s::buffer, PaQaRecording_s::maxFrames, and PaQaRecording_s::numFrames.

int PaQa_SaveRecordingToWaveFile	(	PaQaRecording *	recording,
		const char *	filename
	)

Write recording to WAV file.

References Audio_WAV_CloseWriter(), Audio_WAV_OpenWriter(), Audio_WAV_WriteShorts(), buffer, PaQaRecording_s::buffer, NUM_SAMPLES, PaQaRecording_s::numFrames, and PaQaRecording_s::sampleRate.

void PaQa_SetupSineGenerator	(	PaQaSineGenerator *	generator,
		double	frequency,
		double	amplitude,
		double	frameRate
	)

Prepare an oscillator that can generate a sine tone for testing.

References PaQaSineGenerator_s::amplitude, PaQaSineGenerator_s::frequency, MATH_PI, PaQaSineGenerator_s::phase, and PaQaSineGenerator_s::phaseIncrement.

Referenced by PaQa_FillWithSine(), and PaQa_MeasureLatency().

void PaQa_TerminateRecording

(

PaQaRecording *

recording

)

Free memory allocated by PaQa_InitializeRecording.

References PaQaRecording_s::buffer, and PaQaRecording_s::maxFrames.

Referenced by PaQa_DetectPop().

int PaQa_WriteRecording	(	PaQaRecording *	recording,
		float *	buffer,
		int	numSamples,
		int	stride
	)

Parameters

stride

is the spacing of samples to skip in the input buffer. To use every samples pass 1. To use every other sample pass 2.

References buffer, PaQaRecording_s::buffer, PaQaRecording_s::maxFrames, and PaQaRecording_s::numFrames.

Referenced by PaQa_FillWithSine().

int PaQa_WriteSilence	(	PaQaRecording *	recording,
		int	numSamples
	)

Write zeros into a recording.

References PaQaRecording_s::buffer, PaQaRecording_s::maxFrames, and PaQaRecording_s::numFrames.