Implement visualization support and a spectrum

Borrowing some DFT code from deadbeef, this implements a simple spectrum
visualization into the main toolbar of the app.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Audio/CogAudio.xcodeproj/project.pbxproj

@@ -63,6 +63,10 @@
 		83725A8E27AA0DE60003F694 /* libsoxr.0.dylib in CopyFiles */ = {isa = PBXBuildFile; fileRef = 83725A8A27AA0DBF0003F694 /* libsoxr.0.dylib */; settings = {ATTRIBUTES = (CodeSignOnCopy, ); }; };
 		83725A9027AA16C90003F694 /* Accelerate.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 83725A7B27AA0D8A0003F694 /* Accelerate.framework */; };
 		83725A9127AA16D50003F694 /* AVFoundation.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 83725A7C27AA0D8E0003F694 /* AVFoundation.framework */; };
+		8377C64C27B8C51500E8BC0F /* fft_accelerate.c in Sources */ = {isa = PBXBuildFile; fileRef = 8377C64B27B8C51500E8BC0F /* fft_accelerate.c */; };
+		8377C64E27B8C54400E8BC0F /* fft.h in Headers */ = {isa = PBXBuildFile; fileRef = 8377C64D27B8C54400E8BC0F /* fft.h */; };
+		8377C65227B8CAD100E8BC0F /* VisualizationController.h in Headers */ = {isa = PBXBuildFile; fileRef = 8377C65027B8CAD100E8BC0F /* VisualizationController.h */; };
+		8377C65327B8CAD100E8BC0F /* VisualizationController.m in Sources */ = {isa = PBXBuildFile; fileRef = 8377C65127B8CAD100E8BC0F /* VisualizationController.m */; };
 		8384912718080FF100E7332D /* Logging.h in Headers */ = {isa = PBXBuildFile; fileRef = 8384912618080FF100E7332D /* Logging.h */; };
 		839366671815923C006DD712 /* CogPluginMulti.h in Headers */ = {isa = PBXBuildFile; fileRef = 839366651815923C006DD712 /* CogPluginMulti.h */; };
 		839366681815923C006DD712 /* CogPluginMulti.m in Sources */ = {isa = PBXBuildFile; fileRef = 839366661815923C006DD712 /* CogPluginMulti.m */; };
@@ -159,6 +163,10 @@
 		83725A7C27AA0D8E0003F694 /* AVFoundation.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = AVFoundation.framework; path = System/Library/Frameworks/AVFoundation.framework; sourceTree = SDKROOT; };
 		83725A8827AA0DBF0003F694 /* soxr.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = soxr.h; sourceTree = "<group>"; };
 		83725A8A27AA0DBF0003F694 /* libsoxr.0.dylib */ = {isa = PBXFileReference; lastKnownFileType = "compiled.mach-o.dylib"; path = libsoxr.0.dylib; sourceTree = "<group>"; };
+		8377C64B27B8C51500E8BC0F /* fft_accelerate.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; path = fft_accelerate.c; sourceTree = "<group>"; };
+		8377C64D27B8C54400E8BC0F /* fft.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = fft.h; sourceTree = "<group>"; };
+		8377C65027B8CAD100E8BC0F /* VisualizationController.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = VisualizationController.h; sourceTree = "<group>"; };
+		8377C65127B8CAD100E8BC0F /* VisualizationController.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = VisualizationController.m; sourceTree = "<group>"; };
 		8384912618080FF100E7332D /* Logging.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = Logging.h; path = ../../Utils/Logging.h; sourceTree = "<group>"; };
 		839366651815923C006DD712 /* CogPluginMulti.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = CogPluginMulti.h; sourceTree = "<group>"; };
 		839366661815923C006DD712 /* CogPluginMulti.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = CogPluginMulti.m; sourceTree = "<group>"; };
@@ -235,6 +243,7 @@
 		08FB77AEFE84172EC02AAC07 /* Classes */ = {
 			isa = PBXGroup;
 			children = (
+				8377C64F27B8CAAB00E8BC0F /* Visualization */,
 				17F94DDC0B8D101100A34E87 /* Plugin.h */,
 				17D21EBB0B8BF44000D1EBDE /* AudioPlayer.h */,
 				17D21EBC0B8BF44000D1EBDE /* AudioPlayer.m */,
@@ -326,6 +335,7 @@
 		17D21CD80B8BE5B400D1EBDE /* ThirdParty */ = {
 			isa = PBXGroup;
 			children = (
+				8377C64A27B8C51500E8BC0F /* deadbeef */,
 				83725A8627AA0DBF0003F694 /* libsoxr */,
 				835C88AE279811A500E28EAE /* hdcd */,
 				835C88A22797D4D400E28EAE /* lvqcl */,
@@ -426,6 +436,24 @@
 			name = Frameworks;
 			sourceTree = "<group>";
 		};
+		8377C64A27B8C51500E8BC0F /* deadbeef */ = {
+			isa = PBXGroup;
+			children = (
+				8377C64D27B8C54400E8BC0F /* fft.h */,
+				8377C64B27B8C51500E8BC0F /* fft_accelerate.c */,
+			);
+			path = deadbeef;
+			sourceTree = "<group>";
+		};
+		8377C64F27B8CAAB00E8BC0F /* Visualization */ = {
+			isa = PBXGroup;
+			children = (
+				8377C65027B8CAD100E8BC0F /* VisualizationController.h */,
+				8377C65127B8CAD100E8BC0F /* VisualizationController.m */,
+			);
+			path = Visualization;
+			sourceTree = "<group>";
+		};
 /* End PBXGroup section */
 
 /* Begin PBXHeadersBuildPhase section */
@@ -445,6 +473,7 @@
 				17D21CF30B8BE5EF00D1EBDE /* Semaphore.h in Headers */,
 				17D21DC70B8BE79700D1EBDE /* CoreAudioUtils.h in Headers */,
 				17D21EBD0B8BF44000D1EBDE /* AudioPlayer.h in Headers */,
+				8377C65227B8CAD100E8BC0F /* VisualizationController.h in Headers */,
 				834FD4F027AF93680063BC83 /* ChunkList.h in Headers */,
 				17F94DD50B8D0F7000A34E87 /* PluginController.h in Headers */,
 				17F94DDD0B8D101100A34E87 /* Plugin.h in Headers */,
@@ -460,6 +489,7 @@
 				835C88B1279811A500E28EAE /* hdcd_decode2.h in Headers */,
 				8EC1225F0B993BD500C5B3AD /* ConverterNode.h in Headers */,
 				8384912718080FF100E7332D /* Logging.h in Headers */,
+				8377C64E27B8C54400E8BC0F /* fft.h in Headers */,
 				8E8D3D2F0CBAEE6E00135C1B /* AudioContainer.h in Headers */,
 				B0575F2D0D687A0800411D77 /* Helper.h in Headers */,
 				835C88AD2797DA5800E28EAE /* util.h in Headers */,
@@ -546,6 +576,7 @@
 				8399CF2D27B5D1D5008751F1 /* NSDictionary+Merge.m in Sources */,
 				17D21CA80B8BE4BA00D1EBDE /* Node.m in Sources */,
 				17D21CAA0B8BE4BA00D1EBDE /* OutputNode.m in Sources */,
+				8377C65327B8CAD100E8BC0F /* VisualizationController.m in Sources */,
 				834FD4F527AFA2150063BC83 /* Downmix.m in Sources */,
 				17D21CC60B8BE4BA00D1EBDE /* OutputCoreAudio.m in Sources */,
 				835C88B2279811A500E28EAE /* hdcd_decode2.c in Sources */,
@@ -553,6 +584,7 @@
 				17D21CF40B8BE5EF00D1EBDE /* Semaphore.m in Sources */,
 				8347C7422796C58800FA8A7D /* NSFileHandle+CreateFile.m in Sources */,
 				17D21DC80B8BE79700D1EBDE /* CoreAudioUtils.m in Sources */,
+				8377C64C27B8C51500E8BC0F /* fft_accelerate.c in Sources */,
 				839366681815923C006DD712 /* CogPluginMulti.m in Sources */,
 				835C88AA2797D4D400E28EAE /* lpc.c in Sources */,
 				17D21EBE0B8BF44000D1EBDE /* AudioPlayer.m in Sources */,

Audio/Output/OutputCoreAudio.h

@@ -19,6 +19,8 @@
 
 #import "Downmix.h"
 
+#import "VisualizationController.h"
+
 #import "Semaphore.h"
 
 //#define OUTPUT_LOG
@@ -61,6 +63,8 @@
 	AudioStreamBasicDescription deviceFormat; // info about the default device
 	AudioStreamBasicDescription streamFormat; // stream format last seen in render callback
 
+	AudioStreamBasicDescription visFormat; // Mono format for vis
+
 	uint32_t deviceChannelConfig;
 	uint32_t streamChannelConfig;
 
@@ -70,6 +74,9 @@
 	AudioUnit _eq;
 
 	DownmixProcessor *downmixer;
+	DownmixProcessor *downmixerForVis;
+
+	VisualizationController *visController;
 
 #ifdef OUTPUT_LOG
 	FILE *_logFile;

Audio/Output/OutputCoreAudio.m

@@ -58,6 +58,9 @@ static OSStatus renderCallback(void *inRefCon, AudioUnitRenderActionFlags *ioAct
 
 		amountToRead = inNumberFrames * bytesPerPacket;
 
+		int visTabulated = 0;
+		float visAudio[512]; // Chunk size
+
 		if(_self->stopping == YES || [_self->outputController shouldContinue] == NO) {
 			// Chain is dead, fill out the serial number pointer forever with silence
 			clearBuffers(ioData, amountToRead / bytesPerPacket, 0);
@@ -85,6 +88,7 @@ static OSStatus renderCallback(void *inRefCon, AudioUnitRenderActionFlags *ioAct
 				_self->streamChannelConfig = config;
 				_self->streamFormatStarted = YES;
 				_self->downmixer = [[DownmixProcessor alloc] initWithInputFormat:format inputConfig:config andOutputFormat:_self->deviceFormat outputConfig:_self->deviceChannelConfig];
+				_self->downmixerForVis = [[DownmixProcessor alloc] initWithInputFormat:format inputConfig:config andOutputFormat:_self->visFormat outputConfig:AudioConfigMono];
 			}
 
 			double chunkDuration = [chunk duration];
@@ -94,6 +98,9 @@ static OSStatus renderCallback(void *inRefCon, AudioUnitRenderActionFlags *ioAct
 			float downmixedData[frameCount * channels];
 			[_self->downmixer process:[samples bytes] frameCount:frameCount output:downmixedData];
 
+			[_self->downmixerForVis process:[samples bytes] frameCount:frameCount output:visAudio];
+			visTabulated += frameCount;
+
 			fillBuffers(ioData, downmixedData, frameCount, 0);
 			amountRead = frameCount * bytesPerPacket;
 			[_self->outputController incrementAmountPlayed:chunkDuration];
@@ -113,6 +120,7 @@ static OSStatus renderCallback(void *inRefCon, AudioUnitRenderActionFlags *ioAct
 					_self->streamFormat = format;
 					_self->streamFormatStarted = YES;
 					_self->downmixer = [[DownmixProcessor alloc] initWithInputFormat:format inputConfig:config andOutputFormat:_self->deviceFormat outputConfig:_self->deviceChannelConfig];
+					_self->downmixerForVis = [[DownmixProcessor alloc] initWithInputFormat:format inputConfig:config andOutputFormat:_self->visFormat outputConfig:AudioConfigMono];
 				}
 				atomic_fetch_add(&_self->bytesRendered, frameCount * bytesPerPacket);
 				double chunkDuration = [chunk duration];
@@ -121,6 +129,9 @@ static OSStatus renderCallback(void *inRefCon, AudioUnitRenderActionFlags *ioAct
 				[_self->downmixer process:[samples bytes] frameCount:frameCount output:downmixedData];
 				fillBuffers(ioData, downmixedData, frameCount, amountRead / bytesPerPacket);
 
+				[_self->downmixerForVis process:[samples bytes] frameCount:frameCount output:visAudio + visTabulated];
+				visTabulated += frameCount;
+
 				[_self->outputController incrementAmountPlayed:chunkDuration];
 
 				amountRead += frameCount * bytesPerPacket;
@@ -148,8 +159,12 @@ static OSStatus renderCallback(void *inRefCon, AudioUnitRenderActionFlags *ioAct
 			// buffer loop if it doesn't get anything, so always produce a full
 			// buffer, and silence anything we couldn't supply.
 			clearBuffers(ioData, (amountToRead - amountRead) / bytesPerPacket, amountRead / bytesPerPacket);
+
+			vDSP_vclr(visAudio + visTabulated, 1, 512 - visTabulated);
 		}
 
+		[_self->visController postVisPCM:visAudio];
+
 		return 0;
 	}
 };
@@ -469,7 +484,7 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
 - (void)resetIfOutputChanged {
 	AVAudioFormat *format = _au.outputBusses[0].format;
 
-	if(!restarted && !_deviceFormat || ![_deviceFormat isEqual:format]) {
+	if(!restarted && (!_deviceFormat || ![_deviceFormat isEqual:format])) {
 		[outputController restartPlaybackAtCurrentPosition];
 		restarted = YES;
 	}
@@ -501,6 +516,11 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
 		deviceFormat.mBytesPerFrame = deviceFormat.mChannelsPerFrame * (deviceFormat.mBitsPerChannel / 8);
 		deviceFormat.mBytesPerPacket = deviceFormat.mBytesPerFrame * deviceFormat.mFramesPerPacket;
 
+		visFormat = deviceFormat;
+		visFormat.mChannelsPerFrame = 1;
+		visFormat.mBytesPerFrame = visFormat.mChannelsPerFrame * (visFormat.mBitsPerChannel / 8);
+		visFormat.mBytesPerPacket = visFormat.mBytesPerFrame * visFormat.mFramesPerPacket;
+
 		/* Set the channel layout for the audio queue */
 		AudioChannelLayoutTag tag = 0;
 		switch(deviceFormat.mChannelsPerFrame) {
@@ -579,6 +599,7 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
 	restarted = NO;
 
 	downmixer = nil;
+	downmixerForVis = nil;
 
 	AudioComponentDescription desc;
 	NSError *err;
@@ -720,6 +741,8 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
 
 	[_au allocateRenderResourcesAndReturnError:&err];
 
+	visController = [VisualizationController sharedController];
+
 	[[NSUserDefaultsController sharedUserDefaultsController] addObserver:self forKeyPath:@"values.outputDevice" options:0 context:NULL];
 	[[NSUserDefaultsController sharedUserDefaultsController] addObserver:self forKeyPath:@"values.GraphicEQenable" options:0 context:NULL];
 	observersapplied = YES;
@@ -797,6 +820,9 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
 	if(downmixer) {
 		downmixer = nil;
 	}
+	if(downmixerForVis) {
+		downmixerForVis = nil;
+	}
 #ifdef OUTPUT_LOG
 	if(_logFile) {
 		fclose(_logFile);
@@ -804,6 +830,7 @@ default_device_changed(AudioObjectID inObjectID, UInt32 inNumberAddresses, const
 	}
 #endif
 	outputController = nil;
+	visController = nil;
 }
 
 - (void)dealloc {

Audio/ThirdParty/deadbeef/fft.h

@@ -0,0 +1,40 @@
+/*
+    DeaDBeeF -- the music player
+    Copyright (C) 2009-2021 Alexey Yakovenko and other contributors
+
+    This software is provided 'as-is', without any express or implied
+    warranty.  In no event will the authors be held liable for any damages
+    arising from the use of this software.
+
+    Permission is granted to anyone to use this software for any purpose,
+    including commercial applications, and to alter it and redistribute it
+    freely, subject to the following restrictions:
+
+    1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+
+    2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+
+    3. This notice may not be removed or altered from any source distribution.
+*/
+
+#ifndef FFT_H
+#define FFT_H
+
+#ifdef __cplusplus
+extern "C" {
+}
+#endif
+
+void fft_calculate(const float *data, float *freq, int fft_size);
+
+void fft_free(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

Audio/ThirdParty/deadbeef/fft_accelerate.c

@@ -0,0 +1,95 @@
+/*
+    DeaDBeeF -- the music player
+    Copyright (C) 2009-2021 Alexey Yakovenko and other contributors
+
+    This software is provided 'as-is', without any express or implied
+    warranty.  In no event will the authors be held liable for any damages
+    arising from the use of this software.
+
+    Permission is granted to anyone to use this software for any purpose,
+    including commercial applications, and to alter it and redistribute it
+    freely, subject to the following restrictions:
+
+    1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+
+    2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+
+    3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "fft.h"
+#include <Accelerate/Accelerate.h>
+
+static int _fft_size;
+static float *_input_real;
+static float *_input_imaginary;
+static float *_output_real;
+static float *_output_imaginary;
+static float *_hamming;
+static float *_sq_mags;
+
+static vDSP_DFT_Setup _dft_setup;
+
+static void
+_init_buffers(int fft_size) {
+	if(fft_size != _fft_size) {
+		fft_free();
+
+		_input_real = calloc(fft_size * 2, sizeof(float));
+		_input_imaginary = calloc(fft_size * 2, sizeof(float));
+		_hamming = calloc(fft_size * 2, sizeof(float));
+		_sq_mags = calloc(fft_size, sizeof(float));
+		_output_real = calloc(fft_size * 2, sizeof(float));
+		_output_imaginary = calloc(fft_size * 2, sizeof(float));
+
+		_dft_setup = vDSP_DFT_zop_CreateSetup(NULL, fft_size * 2, FFT_FORWARD);
+		vDSP_hamm_window(_hamming, fft_size * 2, 0);
+
+		_fft_size = fft_size;
+	}
+}
+
+void fft_calculate(const float *data, float *freq, int fft_size) {
+	int dft_size = fft_size * 2;
+
+	_init_buffers(fft_size);
+
+	vDSP_vmul(data, 1, _hamming, 1, _input_real, 1, dft_size);
+
+	vDSP_DFT_Execute(_dft_setup, _input_real, _input_imaginary, _output_real, _output_imaginary);
+
+	DSPSplitComplex split_complex = {
+		.realp = _output_real,
+		.imagp = _output_imaginary
+	};
+	vDSP_zvmags(&split_complex, 1, _sq_mags, 1, fft_size);
+
+	int sq_count = fft_size;
+	vvsqrtf(_sq_mags, _sq_mags, &sq_count);
+
+	float mult = 2.f / fft_size;
+	vDSP_vsmul(_sq_mags, 1, &mult, freq, 1, fft_size);
+}
+
+void fft_free(void) {
+	free(_input_real);
+	free(_input_imaginary);
+	free(_hamming);
+	free(_sq_mags);
+	free(_output_real);
+	free(_output_imaginary);
+	if(_dft_setup != NULL) {
+		vDSP_DFT_DestroySetup(_dft_setup);
+	}
+	_input_real = NULL;
+	_input_imaginary = NULL;
+	_hamming = NULL;
+	_sq_mags = NULL;
+	_dft_setup = NULL;
+	_output_real = NULL;
+	_output_imaginary = NULL;
+}

Audio/Visualization/VisualizationController.h

@@ -0,0 +1,23 @@
+//
+//  VisualizationController.h
+//  CogAudio Framework
+//
+//  Created by Christopher Snowhill on 2/12/22.
+//
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface VisualizationController : NSObject {
+	float visAudio[512];
+}
+
++ (VisualizationController *)sharedController;
+
+- (void)postVisPCM:(const float *)inPCM;
+- (void)copyVisPCM:(float *)outPCM visFFT:(float *)outFFT;
+
+@end
+
+NS_ASSUME_NONNULL_END

Audio/Visualization/VisualizationController.m

@@ -0,0 +1,51 @@
+//
+//  VisualizationController.m
+//  CogAudio Framework
+//
+//  Created by Christopher Snowhill on 2/12/22.
+//
+
+#import "VisualizationController.h"
+#import <Accelerate/Accelerate.h>
+
+#import "fft.h"
+
+@implementation VisualizationController
+
+static VisualizationController *_sharedController = nil;
+
++ (VisualizationController *)sharedController {
+	@synchronized(self) {
+		if(!_sharedController) {
+			_sharedController = [[VisualizationController alloc] init];
+		}
+	}
+	return _sharedController;
+}
+
+- (id)init {
+	self = [super init];
+	if(self) {
+		vDSP_vclr(visAudio, 1, 512);
+	}
+	return self;
+}
+
+- (void)dealloc {
+	fft_free();
+}
+
+- (void)postVisPCM:(const float *)inPCM {
+	@synchronized(self) {
+		cblas_scopy(512, inPCM, 1, visAudio, 1);
+	}
+}
+
+- (void)copyVisPCM:(float *)outPCM visFFT:(float *)outFFT {
+	@synchronized(self) {
+		cblas_scopy(512, visAudio, 1, outPCM, 1);
+		fft_calculate(visAudio, outFFT, 256);
+	}
+}
+
+@end

Base.lproj/MainMenu.xib

@@ -32,7 +32,7 @@
                                 <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                 <clipView key="contentView" drawsBackground="NO" copiesOnScroll="NO" id="KWC-Ti-8KY">
                                     <rect key="frame" x="0.0" y="0.0" width="1000" height="378"/>
-                                    <autoresizingMask key="autoresizingMask"/>
+                                    <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
                                         <tableView focusRingType="none" verticalHuggingPriority="750" allowsExpansionToolTips="YES" alternatingRowBackgroundColors="YES" autosaveName="Playlist" rowHeight="18" headerView="1517" viewBased="YES" id="207" customClass="PlaylistView">
                                             <rect key="frame" x="0.0" y="0.0" width="1000" height="361"/>
@@ -130,11 +130,11 @@
                                                     <tableColumnResizingMask key="resizingMask" resizeWithTable="YES" userResizable="YES"/>
                                                     <prototypeCellViews>
                                                         <tableCellView id="ZCP-Dx-UBV">
-                                                            <rect key="frame" x="106" y="3" width="125.5" height="18"/>
+                                                            <rect key="frame" x="106" y="3" width="126" height="18"/>
                                                             <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                                             <subviews>
                                                                 <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" horizontalCompressionResistancePriority="250" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="exY-Bg-Mjm">
-                                                                    <rect key="frame" x="0.0" y="1" width="125.5" height="16"/>
+                                                                    <rect key="frame" x="0.0" y="1" width="126" height="16"/>
                                                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" flexibleMinY="YES" flexibleMaxY="YES"/>
                                                                     <textFieldCell key="cell" lineBreakMode="truncatingTail" sendsActionOnEndEditing="YES" title="Table View Cell" id="sdo-Sm-KPH">
                                                                         <font key="font" usesAppearanceFont="YES"/>
@@ -876,6 +876,14 @@
                             </connections>
                         </button>
                     </toolbarItem>
+                    <toolbarItem implicitItemIdentifier="5E0A643B-09FC-45CF-A562-C56F1E388E62" label="Spectrum" paletteLabel="Spectrum" sizingBehavior="auto" id="gui-fC-qTP">
+                        <nil key="toolTip"/>
+                        <imageView key="view" horizontalHuggingPriority="251" verticalHuggingPriority="251" id="Zaq-sS-aTV" customClass="SpectrumView">
+                            <rect key="frame" x="0.0" y="14" width="64" height="26"/>
+                            <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMinY="YES"/>
+                            <imageCell key="cell" refusesFirstResponder="YES" alignment="left" imageScaling="proportionallyDown" id="VDu-2p-2bJ"/>
+                        </imageView>
+                    </toolbarItem>
                 </allowedToolbarItems>
                 <defaultToolbarItems>
                     <toolbarItem reference="ZH9-ZU-skw"/>
@@ -888,6 +896,7 @@
                     <toolbarItem reference="1630"/>
                     <toolbarItem reference="1629"/>
                     <toolbarItem reference="1529"/>
+                    <toolbarItem reference="gui-fC-qTP"/>
                     <toolbarItem reference="1568"/>
                     <toolbarItem reference="1551"/>
                     <toolbarItem reference="1610"/>
@@ -1122,6 +1131,14 @@
                             </connections>
                         </button>
                     </toolbarItem>
+                    <toolbarItem implicitItemIdentifier="1A931C99-28FC-4209-BD5C-38E5CF96F7AF" label="Spectrum" paletteLabel="Spectrum" sizingBehavior="auto" id="K64-ro-2GI">
+                        <nil key="toolTip"/>
+                        <imageView key="view" horizontalHuggingPriority="251" verticalHuggingPriority="251" id="F4M-9A-fZv" customClass="SpectrumView">
+                            <rect key="frame" x="0.0" y="14" width="64" height="26"/>
+                            <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMinY="YES"/>
+                            <imageCell key="cell" refusesFirstResponder="YES" alignment="left" imageScaling="proportionallyDown" id="br1-X9-N6H"/>
+                        </imageView>
+                    </toolbarItem>
                 </allowedToolbarItems>
                 <defaultToolbarItems>
                     <toolbarItem reference="qfu-F9-bOZ"/>

Cog.xcodeproj/project.pbxproj

@@ -124,6 +124,7 @@
 		836FB5A718206F2500B3AD2D /* Hively.bundle in CopyFiles */ = {isa = PBXBuildFile; fileRef = 836FB5471820538800B3AD2D /* Hively.bundle */; settings = {ATTRIBUTES = (CodeSignOnCopy, ); }; };
 		8370D73D277419F700245CE0 /* SQLiteStore.m in Sources */ = {isa = PBXBuildFile; fileRef = 8370D73C277419F700245CE0 /* SQLiteStore.m */; };
 		8370D73F2775AE1300245CE0 /* libsqlite3.tbd in Frameworks */ = {isa = PBXBuildFile; fileRef = 8370D73E2775AE1300245CE0 /* libsqlite3.tbd */; };
+		8377C66327B8CF6300E8BC0F /* SpectrumView.m in Sources */ = {isa = PBXBuildFile; fileRef = 8377C66127B8CF6300E8BC0F /* SpectrumView.m */; };
 		8384914018083E4E00E7332D /* filetype.icns in Resources */ = {isa = PBXBuildFile; fileRef = 8384913D18083E4E00E7332D /* filetype.icns */; };
 		8384915918083EAB00E7332D /* infoTemplate.pdf in Resources */ = {isa = PBXBuildFile; fileRef = 8384914318083EAB00E7332D /* infoTemplate.pdf */; };
 		8384915A18083EAB00E7332D /* missingArt@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = 8384914418083EAB00E7332D /* missingArt@2x.png */; };
@@ -942,6 +943,9 @@
 		8370D73C277419F700245CE0 /* SQLiteStore.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = SQLiteStore.m; sourceTree = "<group>"; };
 		8370D73E2775AE1300245CE0 /* libsqlite3.tbd */ = {isa = PBXFileReference; lastKnownFileType = "sourcecode.text-based-dylib-definition"; name = libsqlite3.tbd; path = usr/lib/libsqlite3.tbd; sourceTree = SDKROOT; };
 		8375B05117FFEA400092A79F /* OpusPlugin.xcodeproj */ = {isa = PBXFileReference; lastKnownFileType = "wrapper.pb-project"; name = OpusPlugin.xcodeproj; path = Plugins/Opus/OpusPlugin.xcodeproj; sourceTree = "<group>"; };
+		8377C66127B8CF6300E8BC0F /* SpectrumView.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; name = SpectrumView.m; path = Visualization/SpectrumView.m; sourceTree = "<group>"; };
+		8377C66227B8CF6300E8BC0F /* SpectrumView.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = SpectrumView.h; path = Visualization/SpectrumView.h; sourceTree = "<group>"; };
+		8377C66427B8CF7A00E8BC0F /* VisualizationController.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = VisualizationController.h; path = Audio/Visualization/VisualizationController.h; sourceTree = "<group>"; };
 		8384912518080F2D00E7332D /* Logging.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = Logging.h; sourceTree = "<group>"; };
 		8384913D18083E4E00E7332D /* filetype.icns */ = {isa = PBXFileReference; lastKnownFileType = image.icns; path = filetype.icns; sourceTree = "<group>"; };
 		8384914318083EAB00E7332D /* infoTemplate.pdf */ = {isa = PBXFileReference; lastKnownFileType = image.pdf; name = infoTemplate.pdf; path = Images/infoTemplate.pdf; sourceTree = "<group>"; };
@@ -1073,6 +1077,7 @@
 				835F00B3279BD1CD00055FCF /* Formatters */,
 				177042960B8BC53600B86321 /* Application */,
 				17E0D5D20F520E75005B6FED /* Window */,
+				8377C66027B8CF2300E8BC0F /* Visualization */,
 				8E75752A09F31D5A0080F1EE /* Playlist */,
 				8E07AAEA0AAC90DC00A4B32F /* Preferences */,
 				17DDF6400E0CB6F100A2E4AD /* FileTree */,
@@ -1686,6 +1691,16 @@
 			name = Products;
 			sourceTree = "<group>";
 		};
+		8377C66027B8CF2300E8BC0F /* Visualization */ = {
+			isa = PBXGroup;
+			children = (
+				8377C66427B8CF7A00E8BC0F /* VisualizationController.h */,
+				8377C66227B8CF6300E8BC0F /* SpectrumView.h */,
+				8377C66127B8CF6300E8BC0F /* SpectrumView.m */,
+			);
+			name = Visualization;
+			sourceTree = "<group>";
+		};
 		83B0669D180D5668008E3612 /* Products */ = {
 			isa = PBXGroup;
 			children = (
@@ -2451,6 +2466,7 @@
 				1770429E0B8BC53600B86321 /* PlaybackController.m in Sources */,
 				1766C6930B911DF1004A7AE4 /* AudioScrobbler.m in Sources */,
 				8355D6B6180612F300D05687 /* NSData+MD5.m in Sources */,
+				8377C66327B8CF6300E8BC0F /* SpectrumView.m in Sources */,
 				1766C6950B911DF1004A7AE4 /* AudioScrobblerClient.m in Sources */,
 				1755E1F90BA0D2B600CA3560 /* PlaylistLoader.m in Sources */,
 				8E9A30160BA792DC0091081B /* NSFileHandle+CreateFile.m in Sources */,

Visualization/SpectrumView.h

@@ -0,0 +1,22 @@
+//
+//  SpectrumView.h
+//  Cog
+//
+//  Created by Christopher Snowhill on 2/12/22.
+//
+
+#import <Cocoa/Cocoa.h>
+
+#import "VisualizationController.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface SpectrumView : NSImageView {
+	VisualizationController *visController;
+	NSTimer *timer;
+	NSImage *theImage;
+	BOOL stopped;
+}
+@end
+
+NS_ASSUME_NONNULL_END

Visualization/SpectrumView.m

@@ -0,0 +1,137 @@
+//
+//  SpectrumView.m
+//  Cog
+//
+//  Created by Christopher Snowhill on 2/12/22.
+//
+
+#import "SpectrumView.h"
+
+extern NSString *CogPlaybackDidBeginNotficiation;
+extern NSString *CogPlaybackDidPauseNotficiation;
+extern NSString *CogPlaybackDidResumeNotficiation;
+extern NSString *CogPlaybackDidStopNotficiation;
+
+@implementation SpectrumView
+
+- (void)awakeFromNib {
+	visController = [NSClassFromString(@"VisualizationController") sharedController];
+	timer = nil;
+	theImage = [NSImage imageWithSize:NSMakeSize(64, 26)
+	                          flipped:NO
+	                   drawingHandler:^BOOL(NSRect dstRect) {
+		                   NSColor *backColor = [NSColor textBackgroundColor];
+		                   [backColor drawSwatchInRect:dstRect];
+		                   return YES;
+	                   }];
+
+	stopped = YES;
+
+	[self setImage:theImage];
+	[self setImageScaling:NSImageScaleAxesIndependently];
+
+	[[NSNotificationCenter defaultCenter] addObserver:self
+	                                         selector:@selector(colorsDidChange:)
+	                                             name:NSSystemColorsDidChangeNotification
+	                                           object:nil];
+	[[NSNotificationCenter defaultCenter] addObserver:self
+	                                         selector:@selector(playbackDidBegin:)
+	                                             name:CogPlaybackDidBeginNotficiation
+	                                           object:nil];
+	[[NSNotificationCenter defaultCenter] addObserver:self
+	                                         selector:@selector(playbackDidPause:)
+	                                             name:CogPlaybackDidPauseNotficiation
+	                                           object:nil];
+	[[NSNotificationCenter defaultCenter] addObserver:self
+	                                         selector:@selector(playbackDidResume:)
+	                                             name:CogPlaybackDidResumeNotficiation
+	                                           object:nil];
+	[[NSNotificationCenter defaultCenter] addObserver:self
+	                                         selector:@selector(playbackDidStop:)
+	                                             name:CogPlaybackDidStopNotficiation
+	                                           object:nil];
+}
+
+- (void)repaint {
+	{
+		[theImage lockFocus];
+
+		NSColor *backColor = [NSColor textBackgroundColor];
+		[backColor drawSwatchInRect:NSMakeRect(0, 0, 64, 26)];
+
+		NSBezierPath *bezierPath = [[NSBezierPath alloc] init];
+
+		float visAudio[512], visFFT[256];
+
+		if(!self->stopped) {
+			[self->visController copyVisPCM:&visAudio[0] visFFT:&visFFT[0]];
+		} else {
+			memset(visFFT, 0, sizeof(visFFT));
+		}
+
+		for(int i = 0; i < 60; ++i) {
+			CGFloat y = MAX(MIN(visFFT[i], 0.25), 0.0) * 4.0 * 22.0 + 2.0;
+			[bezierPath moveToPoint:NSMakePoint(2 + i, 2)];
+			[bezierPath lineToPoint:NSMakePoint(2 + i, y)];
+		}
+
+		NSColor *lineColor = [NSColor textColor];
+		[lineColor setStroke];
+
+		[bezierPath stroke];
+
+		[theImage unlockFocus];
+	}
+
+	[self setNeedsDisplay];
+}
+
+- (void)startTimer {
+	[self stopTimer];
+	timer = [NSTimer timerWithTimeInterval:0.02
+	                                target:self
+	                              selector:@selector(timerRun:)
+	                              userInfo:nil
+	                               repeats:YES];
+	[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
+}
+
+- (void)stopTimer {
+	[timer invalidate];
+	timer = nil;
+}
+
+- (void)timerRun:(NSTimer *)timer {
+	[self repaint];
+}
+
+- (void)colorsDidChange:(NSNotification *)notification {
+	[self repaint];
+}
+
+- (void)playbackDidBegin:(NSNotification *)notification {
+	stopped = NO;
+	[self startTimer];
+}
+
+- (void)playbackDidPause:(NSNotification *)notification {
+	stopped = NO;
+	[self stopTimer];
+}
+
+- (void)playbackDidResume:(NSNotification *)notification {
+	stopped = NO;
+	[self startTimer];
+}
+
+- (void)playbackDidStop:(NSNotification *)notification {
+	[self stopTimer];
+	stopped = YES;
+	[self repaint];
+}
+
+- (void)drawRect:(NSRect)dirtyRect {
+	[super drawRect:dirtyRect];
+}
+
+@end