From 37c97e345d12f95dde44e1d1a4c2f2aadd4615bc Mon Sep 17 00:00:00 2001
From: sanine <sanine.not@pm.me>
Date: Thu, 25 Aug 2022 14:54:53 -0500
Subject: add initial structure

---
 portaudio/qa/loopback/src/test_audio_analyzer.c | 718 ++++++++++++++++++++++++
 1 file changed, 718 insertions(+)
 create mode 100644 portaudio/qa/loopback/src/test_audio_analyzer.c

(limited to 'portaudio/qa/loopback/src/test_audio_analyzer.c')

diff --git a/portaudio/qa/loopback/src/test_audio_analyzer.c b/portaudio/qa/loopback/src/test_audio_analyzer.c
new file mode 100644
index 0000000..82fa859
--- /dev/null
+++ b/portaudio/qa/loopback/src/test_audio_analyzer.c
@@ -0,0 +1,718 @@
+
+/*
+ * PortAudio Portable Real-Time Audio Library
+ * Latest Version at: http://www.portaudio.com
+ *
+ * Copyright (c) 1999-2010 Phil Burk and Ross Bencina
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
+ * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/*
+ * The text above constitutes the entire PortAudio license; however,
+ * the PortAudio community also makes the following non-binding requests:
+ *
+ * Any person wishing to distribute modifications to the Software is
+ * requested to send the modifications to the original developer so that
+ * they can be incorporated into the canonical version. It is also
+ * requested that these non-binding requests be included along with the
+ * license above.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include "qa_tools.h"
+#include "audio_analyzer.h"
+#include "test_audio_analyzer.h"
+#include "write_wav.h"
+#include "biquad_filter.h"
+
+#define FRAMES_PER_BLOCK  (64)
+#define PRINT_REPORTS  0
+
+#define TEST_SAVED_WAVE  (0)
+
+/*==========================================================================================*/
+/**
+ * Detect a single tone.
+ */
+static int TestSingleMonoTone( void )
+{
+    int result = 0;
+    PaQaSineGenerator generator;
+    PaQaRecording     recording;
+    float buffer[FRAMES_PER_BLOCK];
+    double sampleRate = 44100.0;
+    int maxFrames = ((int)sampleRate) * 1;
+    int samplesPerFrame = 1;
+    int stride = 1;
+    int done = 0;
+
+    double freq = 234.5;
+    double amp = 0.5;
+
+    double mag1, mag2;
+
+    // Setup a sine oscillator.
+    PaQa_SetupSineGenerator( &generator, freq, amp, sampleRate );
+
+    result = PaQa_InitializeRecording( &recording, maxFrames, (int) sampleRate );
+    QA_ASSERT_EQUALS( "PaQa_InitializeRecording failed", 0, result );
+
+    done = 0;
+    while (!done)
+    {
+        PaQa_EraseBuffer( buffer, FRAMES_PER_BLOCK, samplesPerFrame );
+        PaQa_MixSine( &generator, buffer, FRAMES_PER_BLOCK, stride );
+        done = PaQa_WriteRecording( &recording, buffer, FRAMES_PER_BLOCK, samplesPerFrame );
+    }
+
+    mag1 = PaQa_CorrelateSine( &recording, freq, sampleRate, 0, recording.numFrames, NULL );
+    QA_ASSERT_CLOSE( "exact frequency match", amp, mag1, 0.01 );
+
+    mag2 = PaQa_CorrelateSine( &recording, freq * 1.23, sampleRate, 0, recording.numFrames, NULL );
+    QA_ASSERT_CLOSE( "wrong frequency", 0.0, mag2, 0.01 );
+
+    PaQa_TerminateRecording( &recording );
+    return 0;
+
+error:
+    PaQa_TerminateRecording( &recording);
+    return 1;
+
+}
+
+/*==========================================================================================*/
+/**
+ * Mix multiple tones and then detect them.
+ */
+
+static int TestMixedMonoTones( void )
+{
+    int i;
+    int result = 0;
+#define NUM_TONES (5)
+    PaQaSineGenerator generators[NUM_TONES];
+    PaQaRecording     recording;
+    float buffer[FRAMES_PER_BLOCK];
+    double sampleRate = 44100.0;
+    int maxFrames = ((int)sampleRate) * 1;
+    int samplesPerFrame = 1;
+
+    double baseFreq = 234.5;
+    double amp = 0.1;
+
+    double mag2;
+
+    int stride = samplesPerFrame;
+    int done = 0;
+
+    // Setup a sine oscillator.
+    for( i=0; i<NUM_TONES; i++ )
+    {
+        PaQa_SetupSineGenerator( &generators[i], PaQa_GetNthFrequency( baseFreq, i ), amp, sampleRate );
+    }
+
+    result = PaQa_InitializeRecording( &recording, maxFrames, (int) sampleRate );
+    QA_ASSERT_EQUALS( "PaQa_InitializeRecording failed", 0, result );
+
+    done = 0;
+    while (!done)
+    {
+        PaQa_EraseBuffer( buffer, FRAMES_PER_BLOCK, samplesPerFrame );
+        for( i=0; i<NUM_TONES; i++ )
+        {
+            PaQa_MixSine( &generators[i], buffer, FRAMES_PER_BLOCK, stride );
+        }
+        done = PaQa_WriteRecording( &recording, buffer, FRAMES_PER_BLOCK, samplesPerFrame );
+    }
+
+    for( i=0; i<NUM_TONES; i++ )
+    {
+        double mag = PaQa_CorrelateSine( &recording, PaQa_GetNthFrequency( baseFreq, i), sampleRate, 0, recording.numFrames, NULL );
+        QA_ASSERT_CLOSE( "exact frequency match", amp, mag, 0.01 );
+    }
+
+    mag2 = PaQa_CorrelateSine( &recording, baseFreq * 0.87, sampleRate, 0, recording.numFrames, NULL );
+    QA_ASSERT_CLOSE( "wrong frequency", 0.0, mag2, 0.01 );
+
+    PaQa_TerminateRecording( &recording );
+    return 0;
+
+error:
+    PaQa_TerminateRecording( &recording);
+    return 1;
+
+}
+
+
+/*==========================================================================================*/
+/**
+ * Generate a recording with added or dropped frames.
+ */
+
+static void MakeRecordingWithAddedFrames( PaQaRecording *recording, PaQaTestTone *testTone, int glitchPosition, int framesToAdd )
+{
+    PaQaSineGenerator generator;
+#define BUFFER_SIZE 512
+    float buffer[BUFFER_SIZE];
+
+    int frameCounter = testTone->startDelay;
+
+    int stride = 1;
+    // Record some initial silence.
+    int done = PaQa_WriteSilence( recording, testTone->startDelay );
+
+    // Setup a sine oscillator.
+    PaQa_SetupSineGenerator( &generator, testTone->frequency, testTone->amplitude, testTone->sampleRate );
+
+    while (!done)
+    {
+        int framesThisLoop = BUFFER_SIZE;
+
+        if( frameCounter == glitchPosition )
+        {
+            if( framesToAdd > 0 )
+            {
+                // Record some frozen data without advancing the sine generator.
+                done = PaQa_RecordFreeze( recording, framesToAdd );
+                frameCounter += framesToAdd;
+            }
+            else if( framesToAdd < 0 )
+            {
+                // Advance sine generator a few frames.
+                PaQa_MixSine( &generator, buffer, 0 - framesToAdd, stride );
+            }
+
+        }
+        else if( (frameCounter < glitchPosition) && ((frameCounter + framesThisLoop) > glitchPosition) )
+        {
+            // Go right up to the glitchPosition.
+            framesThisLoop = glitchPosition - frameCounter;
+        }
+
+        if( framesThisLoop > 0 )
+        {
+            PaQa_EraseBuffer( buffer, framesThisLoop, testTone->samplesPerFrame );
+            PaQa_MixSine( &generator, buffer, framesThisLoop, stride );
+            done = PaQa_WriteRecording( recording, buffer, framesThisLoop, testTone->samplesPerFrame );
+        }
+        frameCounter += framesThisLoop;
+    }
+}
+
+
+/*==========================================================================================*/
+/**
+ * Generate a clean recording.
+ */
+
+static void MakeCleanRecording( PaQaRecording *recording, PaQaTestTone *testTone )
+{
+    PaQaSineGenerator generator;
+#define BUFFER_SIZE 512
+    float buffer[BUFFER_SIZE];
+
+    int stride = 1;
+    // Record some initial silence.
+    int done = PaQa_WriteSilence( recording, testTone->startDelay );
+
+    // Setup a sine oscillator.
+    PaQa_SetupSineGenerator( &generator, testTone->frequency, testTone->amplitude, testTone->sampleRate );
+
+    // Generate recording with good phase.
+    while (!done)
+    {
+        PaQa_EraseBuffer( buffer, BUFFER_SIZE, testTone->samplesPerFrame );
+        PaQa_MixSine( &generator, buffer, BUFFER_SIZE, stride );
+        done = PaQa_WriteRecording( recording, buffer, BUFFER_SIZE, testTone->samplesPerFrame );
+    }
+}
+
+/*==========================================================================================*/
+/**
+ * Generate a recording with pop.
+ */
+
+static void MakeRecordingWithPop( PaQaRecording *recording, PaQaTestTone *testTone, int popPosition, int popWidth, double popAmplitude )
+{
+    int i;
+
+    MakeCleanRecording( recording, testTone );
+
+    // Apply glitch to good recording.
+    if( (popPosition + popWidth) >= recording->numFrames )
+    {
+        popWidth = (recording->numFrames - popPosition) - 1;
+    }
+
+    for( i=0; i<popWidth; i++ )
+    {
+        float good = recording->buffer[i+popPosition];
+        float bad = (good > 0.0) ? (good - popAmplitude) : (good + popAmplitude);
+        recording->buffer[i+popPosition] = bad;
+    }
+}
+
+/*==========================================================================================*/
+/**
+ * Detect one phase error in a recording.
+ */
+static int TestDetectSinglePhaseError( double sampleRate, int cycleSize, int latencyFrames, int glitchPosition, int framesAdded )
+{
+    int result = 0;
+    PaQaRecording     recording;
+    PaQaTestTone testTone;
+    PaQaAnalysisResult analysisResult = { 0.0 };
+    int framesDropped = 0;
+    int maxFrames = ((int)sampleRate) * 2;
+
+    testTone.samplesPerFrame = 1;
+    testTone.sampleRate = sampleRate;
+    testTone.frequency = sampleRate / cycleSize;
+    testTone.amplitude = 0.5;
+    testTone.startDelay = latencyFrames;
+
+    result = PaQa_InitializeRecording( &recording, maxFrames, (int) sampleRate );
+    QA_ASSERT_EQUALS( "PaQa_InitializeRecording failed", 0, result );
+
+    MakeRecordingWithAddedFrames( &recording, &testTone, glitchPosition, framesAdded );
+
+    PaQa_AnalyseRecording( &recording, &testTone, &analysisResult );
+
+    if( framesAdded < 0 )
+    {
+        framesDropped = -framesAdded;
+        framesAdded = 0;
+    }
+
+#if PRINT_REPORTS
+    printf("\n=== Dropped Frame Analysis ===================\n");
+    printf("                        expected      actual\n");
+    printf("             latency: %10.3f  %10.3f\n", (double)latencyFrames, analysisResult.latency );
+    printf("    num added frames: %10.3f  %10.3f\n", (double)framesAdded, analysisResult.numAddedFrames );
+    printf("     added frames at: %10.3f  %10.3f\n", (double)glitchPosition, analysisResult.addedFramesPosition );
+    printf("  num dropped frames: %10.3f  %10.3f\n", (double)framesDropped, analysisResult.numDroppedFrames );
+    printf("   dropped frames at: %10.3f  %10.3f\n", (double)glitchPosition, analysisResult.droppedFramesPosition );
+#endif
+
+    QA_ASSERT_CLOSE( "PaQa_AnalyseRecording latency", latencyFrames, analysisResult.latency, 0.5 );
+    QA_ASSERT_CLOSE( "PaQa_AnalyseRecording framesAdded", framesAdded, analysisResult.numAddedFrames, 1.0 );
+    QA_ASSERT_CLOSE( "PaQa_AnalyseRecording framesDropped", framesDropped, analysisResult.numDroppedFrames, 1.0 );
+//    QA_ASSERT_CLOSE( "PaQa_AnalyseRecording glitchPosition", glitchPosition, analysisResult.glitchPosition, cycleSize );
+
+    PaQa_TerminateRecording( &recording );
+    return 0;
+
+error:
+    PaQa_TerminateRecording( &recording);
+    return 1;
+}
+
+/*==========================================================================================*/
+/**
+ * Test various dropped sample scenarios.
+ */
+static int TestDetectPhaseErrors( void )
+{
+    int result;
+
+    result = TestDetectSinglePhaseError( 44100, 200, 477, -1, 0 );
+    if( result < 0 ) return result;
+/*
+    result = TestDetectSinglePhaseError( 44100, 200, 77, -1, 0 );
+    if( result < 0 ) return result;
+
+    result = TestDetectSinglePhaseError( 44100, 200, 83, 3712, 9 );
+    if( result < 0 ) return result;
+
+    result = TestDetectSinglePhaseError( 44100, 280, 83, 3712, 27 );
+    if( result < 0 ) return result;
+
+    result = TestDetectSinglePhaseError( 44100, 200, 234, 3712, -9 );
+    if( result < 0 ) return result;
+
+    result = TestDetectSinglePhaseError( 44100, 200, 2091, 8923, -2 );
+    if( result < 0 ) return result;
+
+    result = TestDetectSinglePhaseError( 44100, 120, 1782, 5772, -18 );
+    if( result < 0 ) return result;
+
+    // Note that if the frequency is too high then it is hard to detect single dropped frames.
+    result = TestDetectSinglePhaseError( 44100, 200, 500, 4251, -1 );
+    if( result < 0 ) return result;
+*/
+    return 0;
+}
+
+/*==========================================================================================*/
+/**
+ * Detect one pop in a recording.
+ */
+static int TestDetectSinglePop( double sampleRate, int cycleSize, int latencyFrames, int popPosition, int popWidth, double popAmplitude )
+{
+    int result = 0;
+    PaQaRecording     recording;
+    PaQaTestTone testTone;
+    PaQaAnalysisResult analysisResult = { 0.0 };
+    int maxFrames = ((int)sampleRate) * 2;
+
+    testTone.samplesPerFrame = 1;
+    testTone.sampleRate = sampleRate;
+    testTone.frequency = sampleRate / cycleSize;
+    testTone.amplitude = 0.5;
+    testTone.startDelay = latencyFrames;
+
+    result = PaQa_InitializeRecording( &recording, maxFrames, (int) sampleRate );
+    QA_ASSERT_EQUALS( "PaQa_InitializeRecording failed", 0, result );
+
+    MakeRecordingWithPop( &recording, &testTone, popPosition, popWidth, popAmplitude );
+
+    PaQa_AnalyseRecording( &recording, &testTone, &analysisResult );
+
+#if PRINT_REPORTS
+    printf("\n=== Pop Analysis ===================\n");
+    printf("                        expected      actual\n");
+    printf("             latency: %10.3f  %10.3f\n", (double)latencyFrames, analysisResult.latency );
+    printf("         popPosition: %10.3f  %10.3f\n", (double)popPosition, analysisResult.popPosition );
+    printf("        popAmplitude: %10.3f  %10.3f\n", popAmplitude, analysisResult.popAmplitude );
+    printf("           cycleSize: %6d\n", cycleSize );
+    printf("    num added frames: %10.3f\n", analysisResult.numAddedFrames );
+    printf("     added frames at: %10.3f\n", analysisResult.addedFramesPosition );
+    printf("  num dropped frames: %10.3f\n", analysisResult.numDroppedFrames );
+    printf("   dropped frames at: %10.3f\n", analysisResult.droppedFramesPosition );
+#endif
+
+    QA_ASSERT_CLOSE( "PaQa_AnalyseRecording latency", latencyFrames, analysisResult.latency, 0.5 );
+    QA_ASSERT_CLOSE( "PaQa_AnalyseRecording popPosition", popPosition, analysisResult.popPosition, 10 );
+    if( popWidth > 0 )
+    {
+        QA_ASSERT_CLOSE( "PaQa_AnalyseRecording popAmplitude", popAmplitude, analysisResult.popAmplitude, 0.1 * popAmplitude  );
+    }
+
+    PaQa_TerminateRecording( &recording );
+    return 0;
+
+error:
+    PaQa_SaveRecordingToWaveFile( &recording, "bad_recording.wav" );
+    PaQa_TerminateRecording( &recording);
+    return 1;
+}
+
+/*==========================================================================================*/
+/**
+ * Analyse recording with a DC offset.
+ */
+static int TestSingleInitialSpike( double sampleRate, int stepPosition, int cycleSize, int latencyFrames, double stepAmplitude )
+{
+    int i;
+    int result = 0;
+    // Account for highpass filter offset.
+    int expectedLatency = latencyFrames + 1;
+    PaQaRecording     recording;
+
+    PaQaRecording     hipassOutput = { 0 };
+    BiquadFilter      hipassFilter;
+
+    PaQaTestTone testTone;
+    PaQaAnalysisResult analysisResult = { 0.0 };
+    int maxFrames = ((int)sampleRate) * 2;
+
+    testTone.samplesPerFrame = 1;
+    testTone.sampleRate = sampleRate;
+    testTone.frequency = sampleRate / cycleSize;
+    testTone.amplitude = -0.5;
+    testTone.startDelay = latencyFrames;
+
+    result = PaQa_InitializeRecording( &recording, maxFrames, (int) sampleRate );
+    QA_ASSERT_EQUALS( "PaQa_InitializeRecording failed", 0, result );
+
+    result = PaQa_InitializeRecording( &hipassOutput, maxFrames, (int) sampleRate );
+    QA_ASSERT_EQUALS( "PaQa_InitializeRecording failed", 0, result );
+
+    MakeCleanRecording( &recording, &testTone );
+
+    // Apply DC step.
+    for( i=stepPosition; i<recording.numFrames; i++ )
+    {
+        recording.buffer[i] += stepAmplitude;
+    }
+
+    // Use high pass as a DC blocker!
+    BiquadFilter_SetupHighPass( &hipassFilter, 10.0 / sampleRate, 0.5 );
+    PaQa_FilterRecording( &recording, &hipassOutput, &hipassFilter );
+
+    testTone.amplitude = 0.5;
+    PaQa_AnalyseRecording( &hipassOutput, &testTone, &analysisResult );
+
+#if PRINT_REPORTS
+    printf("\n=== InitialSpike Analysis ===================\n");
+    printf("                        expected      actual\n");
+    printf("             latency: %10.3f  %10.3f\n", (double)expectedLatency, analysisResult.latency );
+    printf("         popPosition: %10.3f\n", analysisResult.popPosition );
+    printf("        popAmplitude: %10.3f\n", analysisResult.popAmplitude );
+    printf("      amplitudeRatio: %10.3f\n", analysisResult.amplitudeRatio );
+    printf("           cycleSize: %6d\n", cycleSize );
+    printf("    num added frames: %10.3f\n", analysisResult.numAddedFrames );
+    printf("     added frames at: %10.3f\n", analysisResult.addedFramesPosition );
+    printf("  num dropped frames: %10.3f\n", analysisResult.numDroppedFrames );
+    printf("   dropped frames at: %10.3f\n", analysisResult.droppedFramesPosition );
+#endif
+
+    QA_ASSERT_CLOSE( "PaQa_AnalyseRecording latency", expectedLatency, analysisResult.latency, 4.0 );
+    QA_ASSERT_EQUALS( "PaQa_AnalyseRecording no pop from step", -1, (int) analysisResult.popPosition );
+    PaQa_TerminateRecording( &recording );
+    PaQa_TerminateRecording( &hipassOutput );
+    return 0;
+
+error:
+    PaQa_SaveRecordingToWaveFile( &recording, "bad_step_original.wav" );
+    PaQa_SaveRecordingToWaveFile( &hipassOutput, "bad_step_hipass.wav" );
+    PaQa_TerminateRecording( &recording);
+    PaQa_TerminateRecording( &hipassOutput );
+    return 1;
+}
+
+/*==========================================================================================*/
+/**
+ * Test various dropped sample scenarios.
+ */
+static int TestDetectPops( void )
+{
+    int result;
+
+    // No pop.
+    result = TestDetectSinglePop( 44100, 200, 477, -1, 0, 0.0 );
+    if( result < 0 ) return result;
+
+    // short pop
+    result = TestDetectSinglePop( 44100, 300, 810, 3987, 1, 0.5 );
+    if( result < 0 ) return result;
+
+    // medium long pop
+    result = TestDetectSinglePop( 44100, 300, 810, 9876, 5, 0.5 );
+    if( result < 0 ) return result;
+
+    // short tiny pop
+    result = TestDetectSinglePop( 44100, 250, 810, 5672, 1, 0.05 );
+    if( result < 0 ) return result;
+
+
+    return 0;
+}
+
+/*==========================================================================================*/
+/**
+ * Test analysis when there is a DC offset step before the sine signal.
+ */
+static int TestInitialSpike( void )
+{
+    int result;
+
+//( double sampleRate, int stepPosition, int cycleSize, int latencyFrames, double stepAmplitude )
+    // No spike.
+    result = TestSingleInitialSpike( 44100, 32, 100, 537, 0.0 );
+    if( result < 0 ) return result;
+
+    // Small spike.
+    result = TestSingleInitialSpike( 44100, 32, 100, 537, 0.1 );
+    if( result < 0 ) return result;
+
+    // short pop like Ross's error.
+    result = TestSingleInitialSpike( 8000, 32, 42, 2000, 0.1 );
+    if( result < 0 ) return result;
+
+    // Medium spike.
+    result = TestSingleInitialSpike( 44100, 40, 190, 3000, 0.5 );
+    if( result < 0 ) return result;
+
+    // Spike near sine.
+    //result = TestSingleInitialSpike( 44100, 2900, 140, 3000, 0.1 );
+    if( result < 0 ) return result;
+
+
+    return 0;
+}
+
+
+#if TEST_SAVED_WAVE
+/*==========================================================================================*/
+/**
+ * Simple test that writes a sawtooth waveform to a file.
+ */
+static int TestSavedWave()
+{
+    int i,j;
+    WAV_Writer writer;
+    int result = 0;
+#define NUM_SAMPLES  (200)
+    short data[NUM_SAMPLES];
+    short saw = 0;
+
+
+    result =  Audio_WAV_OpenWriter( &writer, "test_sawtooth.wav", 44100, 1 );
+    if( result < 0 ) goto error;
+
+    for( i=0; i<15; i++ )
+    {
+        for( j=0; j<NUM_SAMPLES; j++ )
+        {
+            data[j] = saw;
+            saw += 293;
+        }
+        result =  Audio_WAV_WriteShorts( &writer, data, NUM_SAMPLES );
+        if( result < 0 ) goto error;
+    }
+
+    result =  Audio_WAV_CloseWriter( &writer );
+    if( result < 0 ) goto error;
+
+
+    return 0;
+
+error:
+    printf("ERROR: result = %d\n", result );
+    return result;
+}
+#endif /* TEST_SAVED_WAVE */
+
+/*==========================================================================================*/
+/**
+ * Easy way to generate a sine tone recording.
+ */
+void PaQa_FillWithSine( PaQaRecording *recording, double sampleRate, double freq, double amp )
+{
+    PaQaSineGenerator generator;
+    float buffer[FRAMES_PER_BLOCK];
+    int samplesPerFrame = 1;
+    int stride = 1;
+    int done = 0;
+
+    // Setup a sine oscillator.
+    PaQa_SetupSineGenerator( &generator, freq, amp, sampleRate );
+
+    done = 0;
+    while (!done)
+    {
+        PaQa_EraseBuffer( buffer, FRAMES_PER_BLOCK, samplesPerFrame );
+        PaQa_MixSine( &generator, buffer, FRAMES_PER_BLOCK, stride );
+        done = PaQa_WriteRecording( recording, buffer, FRAMES_PER_BLOCK, samplesPerFrame );
+    }
+
+}
+
+/*==========================================================================================*/
+/**
+ * Generate a tone then knock it out using a filter.
+ * Also check using filter slightly off tune to see if some energy gets through.
+ */
+static int TestNotchFilter( void )
+{
+    int result = 0;
+    PaQaRecording     original = { 0 };
+    PaQaRecording     filtered = { 0 };
+    BiquadFilter      notchFilter;
+    double sampleRate = 44100.0;
+    int maxFrames = ((int)sampleRate) * 1;
+
+    double freq = 234.5;
+    double amp = 0.5;
+
+    double mag1, mag2, mag3;
+
+    result = PaQa_InitializeRecording( &original, maxFrames, (int) sampleRate );
+    QA_ASSERT_EQUALS( "PaQa_InitializeRecording failed", 0, result );
+
+    PaQa_FillWithSine( &original, sampleRate, freq, amp );
+
+    //result = PaQa_SaveRecordingToWaveFile( &original, "original.wav" );
+    //QA_ASSERT_EQUALS( "PaQa_SaveRecordingToWaveFile failed", 0, result );
+
+    mag1 = PaQa_CorrelateSine( &original, freq, sampleRate, 0, original.numFrames, NULL );
+    QA_ASSERT_CLOSE( "exact frequency match", amp, mag1, 0.01 );
+
+    // Filter with exact frequency.
+    result = PaQa_InitializeRecording( &filtered, maxFrames, (int) sampleRate );
+    QA_ASSERT_EQUALS( "PaQa_InitializeRecording failed", 0, result );
+
+    BiquadFilter_SetupNotch( &notchFilter, freq / sampleRate, 0.5 );
+    PaQa_FilterRecording( &original, &filtered, &notchFilter );
+    result = PaQa_SaveRecordingToWaveFile( &filtered, "filtered1.wav" );
+    QA_ASSERT_EQUALS( "PaQa_SaveRecordingToWaveFile failed", 0, result );
+
+    mag2 = PaQa_CorrelateSine( &filtered, freq, sampleRate, 0, filtered.numFrames, NULL );
+    QA_ASSERT_CLOSE( "should eliminate tone", 0.0, mag2, 0.01 );
+
+    // Filter with mismatched frequency.
+    BiquadFilter_SetupNotch( &notchFilter, 1.07 * freq / sampleRate, 2.0 );
+    PaQa_FilterRecording( &original, &filtered, &notchFilter );
+
+    //result = PaQa_SaveRecordingToWaveFile( &filtered, "badfiltered.wav" );
+    //QA_ASSERT_EQUALS( "PaQa_SaveRecordingToWaveFile failed", 0, result );
+
+    mag3 = PaQa_CorrelateSine( &filtered, freq, sampleRate, 0, filtered.numFrames, NULL );
+    QA_ASSERT_CLOSE( "should eliminate tone", amp*0.26, mag3, 0.01 );
+
+
+    PaQa_TerminateRecording( &original );
+    PaQa_TerminateRecording( &filtered );
+    return 0;
+
+error:
+    PaQa_TerminateRecording( &original);
+    PaQa_TerminateRecording( &filtered );
+    return 1;
+
+}
+
+/*==========================================================================================*/
+/**
+ */
+int PaQa_TestAnalyzer( void )
+{
+    int result;
+
+#if TEST_SAVED_WAVE
+    // Write a simple wave file.
+    if ((result = TestSavedWave()) != 0) return result;
+#endif /* TEST_SAVED_WAVE */
+
+    // Generate single tone and verify presence.
+    if ((result = TestSingleMonoTone()) != 0) return result;
+
+    // Generate prime series of tones and verify presence.
+    if ((result = TestMixedMonoTones()) != 0) return result;
+
+    // Detect dropped or added samples in a sine wave recording.
+    if ((result = TestDetectPhaseErrors()) != 0) return result;
+
+    // Test to see if notch filter can knock out the test tone.
+    if ((result = TestNotchFilter()) != 0) return result;
+
+    // Detect pops that get back in phase.
+    if ((result = TestDetectPops()) != 0) return result;
+
+    // Test to see if the latency detector can be tricked like it was on Ross' Windows machine.
+    if ((result = TestInitialSpike()) != 0) return result;
+
+
+    return 0;
+}
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