(committing very old stuff) Lots of changes, no clue

SpectogramPrototype/AudioFile.h

@@ -16,6 +16,6 @@
 + (AudioFile*) audioFileFromURL:(NSURL*) url;
 
 // Reads nSamples of data (left channel), return actual number of samples read
-- (unsigned int) fillLeft:(float*)left andRight:(float*)right withNumberOfSamples:(unsigned int)nSamples;
+- (BOOL) fillLeft:(float*)left andRight:(float*)right forRange:(NSRange)range;
 
 @end

SpectogramPrototype/AudioFile.m

@@ -9,12 +9,29 @@
 #import "AudioFile.h"
 @import AudioToolbox.ExtendedAudioFile;
 
+static const size_t buffer_size = 1 << 12;
+
+@interface Buffer : NSObject  {
+@public
+    float left[buffer_size];
+    float right[buffer_size];
+    NSRange range;
+}
+@end
+
+@implementation Buffer
+@end
+
+
 @interface AudioFile (){
 	ExtAudioFileRef audioFile;
 	AudioStreamBasicDescription format;
+    NSMutableArray * buffers;
 }
 - (id)initWithExtAudioFileRef:(ExtAudioFileRef) audioFile;
 - (void)setupFormat;
+- (Buffer*)getBufferForSample:(NSUInteger) sample;
+- (Buffer*)appendBuffer;
 @end
 
 @implementation AudioFile
@@ -25,6 +42,7 @@
 - (id)initWithExtAudioFileRef:(ExtAudioFileRef) af{
 	if(self = [super init]){
 		audioFile = af;
+        buffers = [[NSMutableArray alloc] init];
 		[self setupFormat];
 	}
 	return self;
@@ -59,22 +77,45 @@
 	return [[AudioFile alloc] initWithExtAudioFileRef:audioFile];
 }
 
-#pragma mark
+- (Buffer *)getBufferForSample:(NSUInteger)sample{
-#pragma mark Usage
+    for (Buffer * b in buffers) {
+        if(NSLocationInRange(sample, b->range)){
+            return b;
+        }
+    }
+    
 
-- (unsigned int)fillLeft:(float *)left andRight:(float *)right withNumberOfSamples:(unsigned int)nSamples {
+    while(1){
-	AudioBufferList bufferList;
+        Buffer * b = [self appendBuffer];
+        if(!b) return nil;
+        if(NSLocationInRange(sample, b->range)) return b;
+    }
+}
+
+- (Buffer *)appendBuffer{
+    Buffer * b = [[Buffer alloc] init];
+    Buffer * last = [buffers lastObject];
+    if(last){
+        b->range.location = last->range.location + last->range.length;
+    } else {
+        b->range.location = 0;
+    }
+    
+    AudioBufferList bufferList;
 	bufferList.mNumberBuffers = 1;
 	bufferList.mBuffers[0].mNumberChannels = 2;
-	bufferList.mBuffers[0].mDataByteSize = nSamples * format.mBytesPerFrame;
+	bufferList.mBuffers[0].mDataByteSize = buffer_size * format.mBytesPerFrame;
 	bufferList.mBuffers[0].mData = calloc(bufferList.mBuffers[0].mDataByteSize, 1);
 	
-	UInt32 nFrames = nSamples;
+	UInt32 nFrames = buffer_size;
 	OSStatus err = ExtAudioFileRead(audioFile, &nFrames, &bufferList);
 	assert(err == 0);
 	
 	short * buffer = bufferList.mBuffers[0].mData;
-	float * leftEnd = left + nSamples;
+    
+    float * left = b->left;
+    float * right = b->right;
+	float * leftEnd = left + buffer_size;
 	for(unsigned int i = 0; i < nFrames; ++i){
 		*left++ = *buffer++ / 32768.0f;
 		*right++ = *buffer++ / 32768.0f;
@@ -85,10 +126,34 @@
 		*left++ = 0;
 		*right++ = 0;
 	}
+    
+    b->range.length = nFrames;
 	
 	free(bufferList.mBuffers[0].mData);
-	
+    
-	return nFrames;
+    if(!nFrames) return nil;
+    [buffers addObject:b];
+    return b;
+}
+
+#pragma mark
+#pragma mark Usage
+
+- (BOOL)fillLeft:(float *)left andRight:(float *)right forRange:(NSRange)range{
+    NSUInteger n = range.length;
+    
+    Buffer * b = nil;
+    while ((b = [self getBufferForSample:range.location])) {
+        while(range.length && NSLocationInRange(range.location, b->range)){
+            *left++ = b->left[range.location - b->range.location];
+            *right++ = b->right[range.location - b->range.location];
+            range.location++;
+            range.length--;
+        }
+        if(range.length == 0) break;
+    }
+    
+    return range.length < n;
 }
 
 @end

SpectogramPrototype/Base.lproj/Main_iPad.storyboard

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="4514" systemVersion="13B42" targetRuntime="iOS.CocoaTouch.iPad" propertyAccessControl="none" useAutolayout="YES" initialViewController="DUW-zh-mwd">
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="4514" systemVersion="13C64" targetRuntime="iOS.CocoaTouch.iPad" propertyAccessControl="none" useAutolayout="YES" initialViewController="DUW-zh-mwd">
     <dependencies>
         <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="3747"/>
     </dependencies>
@@ -43,6 +43,13 @@
                                     <action selector="resetView:" destination="DUW-zh-mwd" eventType="touchUpInside" id="xv9-4L-1Ve"/>
                                 </connections>
                             </button>
+                            <slider opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" value="440" minValue="400" maxValue="480" translatesAutoresizingMaskIntoConstraints="NO" id="ywc-Ak-o9S">
+                                <rect key="frame" x="20" y="100" width="200" height="34"/>
+                                <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
+                                <connections>
+                                    <action selector="tuningChanged:" destination="DUW-zh-mwd" eventType="valueChanged" id="ed0-8G-vOh"/>
+                                </connections>
+                            </slider>
                         </subviews>
                         <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="calibratedWhite"/>
                         <constraints>

SpectogramPrototype/FFTTest.m

@@ -17,7 +17,7 @@
 
 @end
 
-const int logN = 12;
+const int logN = 13;
 const int N = 1 << logN;
 const float scaling = 1.0 / N;
 

SpectogramPrototype/RuledScrollView.m

@@ -54,6 +54,7 @@
 	frame3.size.width = rulerWidth;
 	leftRuler = [[VerticalRuler alloc] initWithFrame:frame3];
 	leftRuler.layer.opacity = 0.5;
+    [(VerticalRuler*)leftRuler setTuning: 440.0f];
 	[self addSubview:leftRuler];
 }
 

SpectogramPrototype/Ruler.h

@@ -21,4 +21,5 @@ typedef struct Interval {
 @end
 
 @interface VerticalRuler : AbstractRuler
+@property (nonatomic) float tuning;
 @end

SpectogramPrototype/Ruler.m

@@ -63,6 +63,12 @@
 
 
 @implementation VerticalRuler
+@synthesize tuning;
+
+- (void)setTuning:(float)tuning_{
+    tuning = tuning_;
+    [self setNeedsDisplay];
+}
 
 - (UIColor*)colorForKey:(int)j{
     switch (j) {
@@ -90,22 +96,22 @@
     
     const CGFloat d = visibleInterval.end - visibleInterval.begin;
     const CGFloat f = 44100;
-    const CGFloat N = 1 << 12;
+    const CGFloat N = 1 << 13;
-    const CGFloat height = (1 << 12) >> 3;
+    const CGFloat height = (1 << 13) >> 3;
     
-    for(int i = 220; i < 44100/8; i *= 2){
+    for(int i = 110; i < 44100/8; i *= 2){
         for(int j = 0; j < 12; ++j){
-            const CGFloat k = i * pow(2, j/12.0);
+            const CGFloat k = (tuning/440.0) * i * pow(2, j/12.0);
             const CGFloat y = N*k/f;
             const CGFloat y2 = (height - y);
-            const CGFloat gy = 1024 * (y2 - visibleInterval.begin) / d;
+            const CGFloat gy = self.bounds.size.height * (y2 - visibleInterval.begin) / d;
             
             [[self colorForKey:j] setFill];
             
             if([UIScreen isRetinaDisplay]){
-                UIRectFill(CGRectMake(0, gy-0.5, self.bounds.size.width, 1.0));
+                UIRectFill(CGRectMake(0, gy, self.bounds.size.width, 0.5));
             } else {
-                UIRectFill(CGRectMake(0, gy-1, self.bounds.size.width, 2.0));
+                UIRectFill(CGRectMake(0, gy, self.bounds.size.width, 1.0));
             }
         }
     }

SpectogramPrototype/Spectographer.m

@@ -19,6 +19,7 @@ uint8_t clamp_to_uint8(float x){
 @interface Spectographer (){
 	FFTTest * FFTHandler;
 	AudioFile * audioFile;
+    NSUInteger sample;
 	float * left;
 	float * right;
 }
@@ -31,6 +32,7 @@ uint8_t clamp_to_uint8(float x){
 - (id)init{
 	if(self = [super init]){
 		FFTHandler = [[FFTTest alloc] init];
+        sample = 0;
 		left = calloc(FFTHandler.acceptedSize, sizeof(float));
 		right = calloc(FFTHandler.acceptedSize, sizeof(float));
 	}
@@ -63,7 +65,7 @@ uint8_t clamp_to_uint8(float x){
 	
 	unsigned int x = 0;
 	for(; x < width; ++x){
-		if(![audioFile fillLeft:left andRight:right withNumberOfSamples:size])
+		if(![audioFile fillLeft:left andRight:right forRange:NSMakeRange(sample, size)])
 			break;
 		[FFTHandler inPlaceFFT:left forSize:size];
 		[FFTHandler inPlaceFFT:right forSize:size];
@@ -74,6 +76,7 @@ uint8_t clamp_to_uint8(float x){
 			rgba[4*width*yy + 4*x + 2] = clamp_to_uint8(10.0f * (left[y] + right[y]));
 			rgba[4*width*yy + 4*x + 3] = 0;
 		}
+        sample += size / 8;
 	}
 	if(!x){
 		free(rgba);

SpectogramPrototype/ViewController.h

@@ -17,5 +17,6 @@
 
 - (IBAction)mediaButtonPressed:(UIButton*)sender;
 - (IBAction)resetView:(id)sender;
+- (IBAction)tuningChanged:(UISlider*)sender;
 
 @end

SpectogramPrototype/ViewController.m

@@ -11,6 +11,7 @@
 #import "ViewController.h"
 #import "RuledScrollView.h"
 #import "Spectographer.h"
+#import "Ruler.h"
 
 typedef enum {
 	iPad,
@@ -175,4 +176,8 @@ device get_device(){
 	[mediaPicker dismissViewControllerAnimated:YES completion:nil];
 }
 
+- (void)tuningChanged:(UISlider*)sender{
+    [(VerticalRuler*)scrollView.leftRuler setTuning:sender.value];
+}
+
 @end

Untitled.md

@@ -0,0 +1,23 @@
+### Output of FFT:
+
+``` 
+	{[DC,NY],C[1],C[2],...,C[n/2]}
+```
+
+### On a sample basis
+Let ps stand for "per sample"
+
+``` C[1] ``` gives the ```1/N``` ps coefficient
+
+``` C[2] ``` gives the ```2/N``` ps coefficient
+
+``` C[N/2] ``` gives the ```1/2``` ps coefficient

### In seconds
Let ```f``` (=44100) be the samplerate. Then:
+
+``` C[1] ``` gives the ```f/N``` hz coefficient
+
+``` C[2] ``` gives the ```2f/N``` hz coefficient
+
+``` C[N/2] ``` gives the ```f/2``` hz coefficient
+
+### From herz to position
+Let ```h``` be some frequency. Then from the above we see that for ``` m := Nh/f ``` we get the ```mf/N = h``` hz coefficient in ``` C[m]```.