It works, we get a spectogram on the ipad :) (still with fixed size and such)

SpectogramPrototype.xcodeproj/project.pbxproj

@@ -29,6 +29,8 @@
 		426665BC1869EF4B005D62AC /* CoreAudio.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 426665BB1869EF4B005D62AC /* CoreAudio.framework */; };
 		426665C11869F194005D62AC /* AudioToolbox.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 426665C01869F194005D62AC /* AudioToolbox.framework */; };
 		426665C51869F50B005D62AC /* MediaPlayer.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 426665C41869F50B005D62AC /* MediaPlayer.framework */; };
+		42E12A91186F122400866CB3 /* testMusic.mp3 in Resources */ = {isa = PBXBuildFile; fileRef = 42E12A90186F122400866CB3 /* testMusic.mp3 */; };
+		42E12A94186F1F4C00866CB3 /* AudioFile.m in Sources */ = {isa = PBXBuildFile; fileRef = 42E12A93186F1F4C00866CB3 /* AudioFile.m */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -71,6 +73,9 @@
 		426665BB1869EF4B005D62AC /* CoreAudio.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = CoreAudio.framework; path = System/Library/Frameworks/CoreAudio.framework; sourceTree = SDKROOT; };
 		426665C01869F194005D62AC /* AudioToolbox.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = AudioToolbox.framework; path = System/Library/Frameworks/AudioToolbox.framework; sourceTree = SDKROOT; };
 		426665C41869F50B005D62AC /* MediaPlayer.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = MediaPlayer.framework; path = System/Library/Frameworks/MediaPlayer.framework; sourceTree = SDKROOT; };
+		42E12A90186F122400866CB3 /* testMusic.mp3 */ = {isa = PBXFileReference; lastKnownFileType = audio.mp3; path = testMusic.mp3; sourceTree = "<group>"; };
+		42E12A92186F1F4C00866CB3 /* AudioFile.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = AudioFile.h; sourceTree = "<group>"; };
+		42E12A93186F1F4C00866CB3 /* AudioFile.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = AudioFile.m; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -104,6 +109,7 @@
 		424F849C18661F8000687D3B = {
 			isa = PBXGroup;
 			children = (
+				42E12A90186F122400866CB3 /* testMusic.mp3 */,
 				424F84AE18661F8000687D3B /* SpectogramPrototype */,
 				424F84D018661F8000687D3B /* SpectogramPrototypeTests */,
 				424F84A718661F8000687D3B /* Frameworks */,
@@ -144,6 +150,8 @@
 				424F84BD18661F8000687D3B /* Main_iPad.storyboard */,
 				424F84C018661F8000687D3B /* ViewController.h */,
 				424F84C118661F8000687D3B /* ViewController.m */,
+				42E12A92186F1F4C00866CB3 /* AudioFile.h */,
+				42E12A93186F1F4C00866CB3 /* AudioFile.m */,
 				426665B31869A7CC005D62AC /* RuledScrollView.h */,
 				426665B41869A7CC005D62AC /* RuledScrollView.m */,
 				426665B61869CEFE005D62AC /* FFTTest.h */,
@@ -263,6 +271,7 @@
 				424F84BF18661F8000687D3B /* Main_iPad.storyboard in Resources */,
 				424F84C418661F8000687D3B /* Images.xcassets in Resources */,
 				424F84BC18661F8000687D3B /* Main_iPhone.storyboard in Resources */,
+				42E12A91186F122400866CB3 /* testMusic.mp3 in Resources */,
 				4261F08818671ECD00AA0EF9 /* ContentView.xib in Resources */,
 				424F84B318661F8000687D3B /* InfoPlist.strings in Resources */,
 			);
@@ -283,6 +292,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				42E12A94186F1F4C00866CB3 /* AudioFile.m in Sources */,
 				426665B81869CEFE005D62AC /* FFTTest.m in Sources */,
 				424F84C218661F8000687D3B /* ViewController.m in Sources */,
 				424F84B918661F8000687D3B /* AppDelegate.m in Sources */,

SpectogramPrototype/AudioFile.h

@@ -0,0 +1,21 @@
+//
+//  AudioFile.h
+//  SpectogramPrototype
+//
+//  Created by Joshua Moerman on 28/12/13.
+//  Copyright (c) 2013 Joshua Moerman. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+// Uses the ExtAudioFileRef from the AudioToolkit
+// Handles conversion to PCM and such
+@interface AudioFile : NSObject
+
+// Loads a file (and sets the right internal format)
++ (AudioFile*) audioFileFromURL:(NSURL*) url;
+
+// Reads nSamples of data (left channel), return actual number of samples read
+- (unsigned int) fillArray:(float*)array withNumberOfSamples:(unsigned int)nSamples;
+
+@end

SpectogramPrototype/AudioFile.m

@@ -0,0 +1,93 @@
+//
+//  AudioFile.m
+//  SpectogramPrototype
+//
+//  Created by Joshua Moerman on 28/12/13.
+//  Copyright (c) 2013 Joshua Moerman. All rights reserved.
+//
+
+#import "AudioFile.h"
+#import <AudioToolbox/ExtendedAudioFile.h>
+
+@interface AudioFile (){
+	ExtAudioFileRef audioFile;
+	AudioStreamBasicDescription format;
+}
+- (id)initWithExtAudioFileRef:(ExtAudioFileRef) audioFile;
+- (void)setupFormat;
+@end
+
+@implementation AudioFile
+
+#pragma mark
+#pragma mark Creation
+
+- (id)initWithExtAudioFileRef:(ExtAudioFileRef) af{
+	if(self = [super init]){
+		audioFile = af;
+		[self setupFormat];
+	}
+	return self;
+}
+
+- (void)setupFormat{
+	format.mSampleRate        = 44100.0f;
+	format.mFormatID          = kAudioFormatLinearPCM;
+	format.mFormatFlags       = kLinearPCMFormatFlagIsPacked | kLinearPCMFormatFlagIsSignedInteger;
+	format.mBytesPerPacket    = 4;
+	format.mFramesPerPacket   = 1;
+	format.mBytesPerFrame     = 4;
+	format.mChannelsPerFrame  = 2;
+	format.mBitsPerChannel    = 16;
+	format.mReserved          = 0;
+	
+	UInt32 size = sizeof(format);
+	OSStatus err = ExtAudioFileSetProperty(audioFile, kExtAudioFileProperty_ClientDataFormat, size, &format);
+	assert(err == 0);
+}
+
+- (void)dealloc {
+	OSStatus err = ExtAudioFileDispose(audioFile);
+	assert(err == 0);
+}
+
++ (AudioFile *)audioFileFromURL:(NSURL *)url{
+	ExtAudioFileRef audioFile = NULL;
+	OSStatus err = ExtAudioFileOpenURL((__bridge CFURLRef) url, &audioFile);
+	assert(err == 0 && audioFile);
+
+	return [[AudioFile alloc] initWithExtAudioFileRef:audioFile];
+}
+
+#pragma mark
+#pragma mark Usage
+
+- (unsigned int)fillArray:(float *)array withNumberOfSamples:(unsigned int)nSamples{
+	AudioBufferList bufferList;
+	bufferList.mNumberBuffers = 1;
+	bufferList.mBuffers[0].mNumberChannels = 2;
+	bufferList.mBuffers[0].mDataByteSize = nSamples * format.mBytesPerFrame;
+	bufferList.mBuffers[0].mData = calloc(bufferList.mBuffers[0].mDataByteSize, 1);
+	
+	UInt32 nFrames = nSamples;
+	OSStatus err = ExtAudioFileRead(audioFile, &nFrames, &bufferList);
+	assert(err == 0);
+	
+	short * buffer = bufferList.mBuffers[0].mData;
+	float * end = array + nSamples;
+	for(unsigned int i = 0; i < nFrames; ++i){
+		*array++ = *buffer++ / 32768.0;
+		// skip right channel
+		buffer++;
+	}
+	
+	while(array != end){
+		*array++ = 0.0;
+	}
+	
+	free(bufferList.mBuffers[0].mData);
+	
+	return nFrames;
+}
+
+@end

SpectogramPrototype/Base.lproj/Main_iPad.storyboard

@@ -21,17 +21,6 @@
                                 <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
                                 <color key="backgroundColor" red="0.40000000600000002" green="1" blue="0.40000000600000002" alpha="1" colorSpace="calibratedRGB"/>
                             </scrollView>
-                            <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="Bzu-fO-jsM">
-                                <rect key="frame" x="200" y="200" width="111" height="42"/>
-                                <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
-                                <fontDescription key="fontDescription" type="system" pointSize="22"/>
-                                <state key="normal" title="Calculate!">
-                                    <color key="titleShadowColor" white="0.5" alpha="1" colorSpace="calibratedWhite"/>
-                                </state>
-                                <connections>
-                                    <action selector="calculateButtonPressed:" destination="DUW-zh-mwd" eventType="touchUpInside" id="4Rp-2D-265"/>
-                                </connections>
-                            </button>
                             <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="kj8-JR-vKG">
                                 <rect key="frame" x="200" y="300" width="111" height="42"/>
                                 <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>

SpectogramPrototype/FFTTest.m

@@ -17,7 +17,7 @@
 
 @end
 
-const int logN = 3;
+const int logN = 12;
 const int N = 1 << logN;
 const float scaling = 1.0 / N;
 
@@ -28,11 +28,15 @@ const float scaling = 1.0 / N;
 	if(self = [super init]){
 		acceptedSize = N;
 		
+		// allocate structs
 		setup = vDSP_create_fftsetup(logN, kFFTRadix2);
 		window = calloc(N, sizeof(float));
 		buffer = calloc(N, sizeof(float));
 		
 		assert(setup && window && buffer);
+		
+		// initialize bits
+		vDSP_blkman_window(window, N, 0);
 	}
 	return self;
 }
@@ -46,15 +50,8 @@ const float scaling = 1.0 / N;
 - (void)inPlaceFFT:(float *)data forSize:(unsigned int)n{
 	assert(n == N);
 	
-	// Output the source data
-	for(int i = 0; i < N; ++i){
-		printf("%f, ", data[i]);
-	}
-	printf("\n");
-	
-	// Window our time - slice
-	//	vDSP_blkman_window(window, N, 0);
-	//	vmul(data, 1, window, 1, data, 1, N);
+	// Windowing
+	vDSP_vmul(data, 1, window, 1, data, 1, N);
 	
 	// Rearrange data
 	DSPSplitComplex split_buffer = { buffer, buffer + N/2 };
@@ -67,11 +64,5 @@ const float scaling = 1.0 / N;
 	vDSP_zvabs(&split_buffer, 1, data, 1, N/2);
 	vDSP_vsmul(data, 1, &scaling, data, 1, N/2);
 	
-	// Output results:
-	for(int i = 0; i < N/2; ++i){
-		printf("%f, ", data[i]);
-	}
-	printf("\n");
-	
 }
 @end

SpectogramPrototype/RuledScrollView.m

@@ -68,14 +68,15 @@
 
 - (void)placeTicks {
 	[topRuler.subviews makeObjectsPerformSelector:@selector(removeFromSuperview)];
-	for (CGFloat x = rulerWidth + 50; x < topRuler.frame.size.width; x += 100){
+	CGFloat spacing = 600.0f;
+	for (CGFloat x = rulerWidth + 0.5*spacing; x < topRuler.frame.size.width; x += spacing){
 		UIView * line = [[UIView alloc] initWithFrame:CGRectMake(x, 0, 1, rulerHeight)];
 		line.backgroundColor = [UIColor blackColor];
 		[topRuler addSubview:line];
 		
 		CGFloat width = 100;
 		UILabel * text = [[UILabel alloc] initWithFrame:CGRectMake(x - width/2, 0, width, rulerHeight)];
-		text.text = [NSString stringWithFormat:@"%.0f", x];
+		text.text = [NSString stringWithFormat:@"%.0f", 0.1 * x];
 		text.textAlignment = NSTextAlignmentCenter;
 		[topRuler addSubview:text];
 	}

SpectogramPrototype/ViewController.h

@@ -15,7 +15,6 @@
 @property (nonatomic) IBOutlet RuledScrollView * scrollView;
 @property (nonatomic) IBOutlet UIView * contentView;
 
-- (IBAction) calculateButtonPressed:(id)sender;
 - (IBAction) mediaButtonPressed:(UIButton*)sender;
 
 @end

SpectogramPrototype/ViewController.m

@@ -12,10 +12,42 @@
 #import "ViewController.h"
 #import "RuledScrollView.h"
 #import "FFTTest.h"
+#import "AudioFile.h"
+
+typedef enum {
+	iPad,
+	iPod,
+	Simulator
+} device;
+
+// NOTE: the simulator has no media, so we cant use MPMediaPicker
+// and the iPad has to use a popover, while the iPod/iPhone doesn't
+// So that's why we check the device
+device get_device(){
+	device device = iPad;
+	
+	NSRange range = [[[UIDevice currentDevice] model] rangeOfString:@"Simulator"];
+	if(range.location != NSNotFound) {
+		device = Simulator;
+	}
+
+	if([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone){
+		device = iPod;
+	}
+	
+	return device;
+}
+
+UInt8 clamp_to_uint8(float x){
+	if(x >= 1.0) return 255;
+	if(x <= 0.0) return 0;
+	return 255.0 * x;
+}
 
 @interface ViewController () <MPMediaPickerControllerDelegate> {
 	UIPopoverController * pop;
 	FFTTest * fft_handler;
+	float * data;
 }
 - (void) openAudioFile:(NSURL*)filePath;
 @property (nonatomic, strong) UILabel* header;
@@ -40,57 +72,90 @@
 	[super didReceiveMemoryWarning];
 }
 
-- (void)calculateButtonPressed:(id)sender{
+- (void)openAudioFile:(NSURL *)filePath{
+	AudioFile * audioFile = [AudioFile audioFileFromURL:filePath];
+	
 	if(!fft_handler)
 		fft_handler = [[FFTTest alloc] init];
 	
 	unsigned int size = fft_handler.acceptedSize;
-	float * data = calloc(size, sizeof(float));
-	[fft_handler inPlaceFFT:data forSize:size];
-	free(data);
-}
-
-- (void)openAudioFile:(NSURL *)filePath{
-	OSStatus err;
+	unsigned int width = size/4;
+	unsigned int height = size/8;
 	
-	ExtAudioFileRef audioFile = NULL;
-	err = ExtAudioFileOpenURL((__bridge CFURLRef) filePath, &audioFile);
-	assert(err == 0);
+	if(!data)
+		data = calloc(size, sizeof(float));
 	
-	AudioBufferList bufferList;
-	bufferList.mNumberBuffers = 1;
-	bufferList.mBuffers[0].mNumberChannels = 2;
-	bufferList.mBuffers[0].mDataByteSize = 32768;
-	bufferList.mBuffers[0].mData = calloc(32768, 1);
+	char * rgba = calloc(width*height*4, sizeof(char));
 	
-	while(true){
-		bufferList.mBuffers[0].mDataByteSize = 32768;
-		
-		UInt32 nFrames = 32768 / 6;
-		err = ExtAudioFileRead(audioFile, &nFrames, &bufferList);
-		assert(err == 0);
-		if(!nFrames) break;
+	for(unsigned int x = 0; x < width; ++x){
+		[audioFile fillArray:data withNumberOfSamples:size];
+		[fft_handler inPlaceFFT:data forSize:size];
+		for(unsigned int y = 0; y < height; ++y){
+			unsigned int yy = height - y - 1;
+			rgba[4*width*yy + 4*x + 0] = clamp_to_uint8(100.0 * data[y]);
+			rgba[4*width*yy + 4*x + 1] = clamp_to_uint8(50.0 * data[y]);
+			rgba[4*width*yy + 4*x + 2] = clamp_to_uint8(10.0 * data[y]);
+			rgba[4*width*yy + 4*x + 3] = 0;
+		}
 	}
 	
-	NSLog(@"Read some bits");
+	CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
+	assert(colorSpace);
+	CGContextRef bitmapContext = CGBitmapContextCreate(rgba, width, height, 8, 4*width, colorSpace, (CGBitmapInfo)kCGImageAlphaNoneSkipLast);
+	assert(bitmapContext);
+	CGImageRef cgImage = CGBitmapContextCreateImage(bitmapContext);
+	assert(cgImage);
+	UIImage * newUIImage = [UIImage imageWithCGImage:cgImage];
+	assert(newUIImage);
 	
-	err = ExtAudioFileDispose(audioFile);
-	assert(err == 0);
+	CGColorSpaceRelease(colorSpace);
+	CGContextRelease(bitmapContext);
+	CGImageRelease(cgImage);
+	free(rgba);
+	
+	UIImageView * view = [[UIImageView alloc] initWithImage:newUIImage];
+	view.frame = CGRectMake(0, 0, width, height);
+	
+	[contentView removeFromSuperview];
+	contentView = view;
+	
+	[scrollView.content addSubview:contentView];
+	contentView.autoresizingMask = UIViewAutoresizingNone;
+	scrollView.contentSize = contentView.bounds.size;
 }
 
 - (void)mediaButtonPressed:(UIButton*)sender{
-	MPMediaPickerController * mppc = [[MPMediaPickerController alloc] initWithMediaTypes:MPMediaTypeAnyAudio];
-	mppc.delegate = self;
-	mppc.allowsPickingMultipleItems = NO;
-	mppc.showsCloudItems = NO;
-
-	if(pop){
-		[pop dismissPopoverAnimated:YES];
-		pop = nil;
-	}
+	MPMediaPickerController * mppc = nil;
+	device device = get_device();
 	
-	pop = [[UIPopoverController alloc] initWithContentViewController:mppc];
-	[pop presentPopoverFromRect:sender.frame inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
+	switch (device) {
+		case iPad:
+			mppc = [[MPMediaPickerController alloc] initWithMediaTypes:MPMediaTypeAnyAudio];
+			mppc.delegate = self;
+			mppc.allowsPickingMultipleItems = NO;
+			mppc.showsCloudItems = NO;
+			
+			if(pop){
+				[pop dismissPopoverAnimated:YES];
+				pop = nil;
+			}
+			
+			pop = [[UIPopoverController alloc] initWithContentViewController:mppc];
+			[pop presentPopoverFromRect:sender.frame inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
+			break;
+		case iPod:
+			mppc = [[MPMediaPickerController alloc] initWithMediaTypes:MPMediaTypeAnyAudio];
+			mppc.delegate = self;
+			mppc.allowsPickingMultipleItems = NO;
+			mppc.showsCloudItems = NO;
+			
+			[self presentViewController:mppc animated:YES completion:nil];
+			break;
+		case Simulator:
+			NSLog(@"WARNING: No MPMediaPicker in Simulator, opening some file");
+			[self openAudioFile:[[NSBundle mainBundle] URLForResource:@"testMusic" withExtension:@".mp3"]];
+			break;
+	}
 }
 
 - (void)mediaPicker:(MPMediaPickerController *)mediaPicker didPickMediaItems:(MPMediaItemCollection *)mediaItemCollection {