Tutorial 28 - Codea Audio Player Add On (Enhanced)

AppDelegate.h

//
//  AppDelegate.h
//  LunarLander HD
//
//  Created by Reefwing Software on Saturday, 13 April 2013
//  Copyright (c) Reefwing Software. All rights reserved.
//

#import <UIKit/UIKit.h>
#import "AudioAddon.h"

@class CodeaViewController;

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) AudioAddOn *audioAddOn;
@property (strong, nonatomic) UIWindow *window;
@property (strong, nonatomic) CodeaViewController *viewController;

@end

AppDelegate.mm

//
//  AppDelegate.mm
//  LunarLander HD
//
//  Created by Reefwing Software on Saturday, 13 April 2013
//  Copyright (c) Reefwing Software. All rights reserved.
//

#import "AppDelegate.h"
#import "CodeaViewController.h"

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.viewController = [[CodeaViewController alloc] init];
    
    //  Create and add our AudioAddOn to Codea
    
    self.audioAddOn = [[AudioAddOn alloc] init];
    [self.viewController registerAddon: self.audioAddOn];
    
    NSString* projectPath = [[[NSBundle mainBundle] bundlePath] stringByAppendingPathComponent:@"LunarLanderHD.codea"];
    
    [self.viewController loadProjectAtPath:projectPath];
    
    self.window.rootViewController = self.viewController;
    [self.window makeKeyAndVisible];
    
    return YES;
}

- (void)applicationWillResignActive:(UIApplication *)application
{
}

- (void)applicationDidEnterBackground:(UIApplication *)application
{
}

- (void)applicationWillEnterForeground:(UIApplication *)application
{
}

- (void)applicationDidBecomeActive:(UIApplication *)application
{
}

- (void)applicationWillTerminate:(UIApplication *)application
{
}

@end

AudioAddOn.h

//
//  AudioAddOn.h
//  AudioDemo
//
//  Created by David Such on 13/04/13.
//  Copyright (c) 2013 Reefwing Software. All rights reserved.
//
//  Version:    1.0 - Original (13/04/13)
//              1.1 - Volume control & monitoring added, metering enabled (14/04/14)

#import <Foundation/Foundation.h>
#import <AVFoundation/AVFoundation.h>
#import "CodeaAddon.h"

id audioAddOnInstance;

//  This class conforms to the CodeaAddon & AVAudioPlayerDelegate Protocols 

@interface AudioAddOn : NSObject<CodeaAddon, AVAudioPlayerDelegate>

@property (strong, nonatomic) AVAudioPlayer *player;

//  Forward declare our Lua Audio functions. These are static to confine their scope
//  to this file. By default c functions are global.

static int playMusic(struct lua_State *state);
static int stopMusic(struct lua_State *state);

static int getVolume(struct lua_State *state);
static int setVolume(struct lua_State *state);

static int peakPowerForChannel(struct lua_State *state);
static int averagePowerForChannel(struct lua_State *state);

@end

AudioAddOn.m

//
//  AudioAddOn.m
//  AudioDemo
//
//  Created by David Such on 13/04/13.
//  Copyright (c) 2013 Reefwing Software. All rights reserved.
//
//  Version:    1.0 - Original (13/04/13)
//              1.1 - Volume control & monitoring added, metering enabled (14/04/14)

#import "AudioAddOn.h"
#import "lua.h"

@implementation AudioAddOn

#pragma mark - Initialisation

- (id)init
{
    self = [super init];
    if (self)
    {
        //  Initialise the Audio Player with your mp3 file.
        
        NSURL *url = [NSURL fileURLWithPath:[[NSBundle mainBundle]
                                             pathForResource:@"LunarLander"
                                             ofType:@"mp3"]];
        
        NSError *error;
        
        _player = [[AVAudioPlayer alloc] initWithContentsOfURL: url error: &error];
        
        if (error)
            NSLog(@"Error initialiasing Audio Add On: %@", [error localizedDescription]);
        else
        {
            // Player initialised, assign delegate to this class
            
            [_player setDelegate: self];
            
            //  Calling prepareToPlay preloads buffers and acquires the audio hardware needed for playback,
            //  which minimizes the lag between calling the play method and the start of sound output.
            
            [_player prepareToPlay];
            
            //  A value of 0, which is the default, means to play the sound once. Set a positive integer
            //  value to specify the number of times to return to the start and play again. For example,
            //  specifying a value of 1 results in a total of two plays of the sound. Set any negative
            //  integer value to loop the sound indefinitely until you call the stop method.
            
            [_player setNumberOfLoops: -1];
            
            //  The default value for the meteringEnabled property is off (Boolean NO). Before using metering
            //  for an audio player, you need to enable it by setting this property to YES.
            
            [_player setMeteringEnabled: YES];
            
            //  audioAddOnInstance allows us to access self from within the c functions.
            
            audioAddOnInstance = self;
        }
    }
    return self;
}

#pragma mark - CodeaAddon Delegate

//  Classes which comply with the <CodeaAddon> Protocol must implement this method

- (void) codea:(CodeaViewController*)controller didCreateLuaState:(struct lua_State*)L
{
    NSLog(@"AudioAddon Registering Functions");
    
    //  Register the Audio functions, defined below
    
    lua_register(L, "playMusic", playMusic);
    lua_register(L, "stopMusic", stopMusic);
    lua_register(L, "setVolume", setVolume);
    lua_register(L, "getVolume", getVolume);
    lua_register(L, "peakPowerForChannel", peakPowerForChannel);
    lua_register(L, "averagePowerForChannel", averagePowerForChannel);
}

//  Optional method

- (void) codeaWillDrawFrame:(CodeaViewController*)controller withDelta:(CGFloat)deltaTime
{
    
}

#pragma mark - Audio Add On Functions and associated Methods

//  Objective C Methods

- (void)startPlayer
{
    [self.player play];
}

- (void)stopPlayer
{
    if ([self.player isPlaying])
        [self.player stop];
}

- (void)setPlayerVolume: (int)setting
{
    // The volume property is the playback gain for the AV audio player object,
    // it expects a float ranging from 0.0 through 1.0.
    //
    // Our Codea slider control returns an integer from 0 to 100 so we need to
    // convert this to a float in the appropriate range before applying it to
    // our player. As a defensive measure we will clamp the result between 0.0 and 1.0.
    
    float floatSetting = MAX(0.0f, MIN((float)setting / 100.0f, 1.0f));
    
    [self.player setVolume: floatSetting];
}

- (int)getPlayerVolume
{
    return (self.player.volume * 100.0f);
}

- (int)getPeakPower: (NSUInteger)channel
{
    if ([self.player isPlaying])
    {
        //  Refresh the average and peak power values for all channels of our audio player.
        
        [self.player updateMeters];
        
        //  Peak power is a floating-point representation, in decibels, of a given audio channel’s current peak power.
        //  A return value of 0 dB indicates full scale, or maximum power while a return value of -160 dB indicates
        //  minimum power (that is, near silence).
        //
        //  If the signal provided to the audio player exceeds ±full scale, then the return value may exceed 0
        //  (that is, it may enter the positive range).
        //
        //  Channel numbers are zero-indexed. A monaural signal, or the left channel of a stereo signal, has channel number 0.
        
        float power = -160.0f;  // Initialise to silence
        
        if (channel <= [self.player numberOfChannels])
            power = [self.player peakPowerForChannel: channel];
        
        //  Our dial is expecting a value between 0 and 100.
        
        if (power >= 0)
            return 100;
        else
        {
            power += 160.0f;                        //  power is now a +ve float between 0 and 160
            power = (power / 160.0f) * 100.0f;      //  change to a percentage
            return (int)power;
        }
    }
    else
        return 0;
}

- (int)getAveragePower: (NSUInteger)channel
{
    if ([self.player isPlaying])
    {
        //  Refresh the average and peak power values for all channels of our audio player.
        
        [self.player updateMeters];
        
        //  A floating-point representation, in decibels, of a given audio channel’s current average power.
        //  A return value of 0 dB indicates full scale, or maximum power; a return value of -160 dB indicates
        //  minimum power (that is, near silence).
        //
        //  If the signal provided to the audio player exceeds ±full scale, then the return value may exceed 0
        //  (that is, it may enter the positive range).
        //
        //  Channel numbers are zero-indexed. A monaural signal, or the left channel of a stereo signal, has channel number 0.
        
        float power = -160.0f;  // Initialise to silence
        
        if (channel <= [self.player numberOfChannels])
            power = [self.player averagePowerForChannel: channel];
        
        //  Our dial is expecting a value between 0 and 100.
        
        if (power >= 0)
            return 100;
        else
        {
            power += 160.0f;                        //  power is now a +ve float between 0 and 160
            power = (power / 160.0f) * 100.0f;      //  change to a percentage
            return (int)power;
        }
    }
    else
        return 0;
}

//  C Functions
//
//  Note that the returned value from all exported Lua functions is how many values that function should return in Lua.
//  For example, if you return 0 from that function, you are telling Lua that peakPowerForPlayer (for example) returns 0 values.
//  If you return 2, you are telling Lua to expect 2 values on the stack when the function returns.
//
//  To actually return values, you need to push them onto the Lua stack and then return the number of values you pushed on.

static int playMusic(struct lua_State *state)
{
    [audioAddOnInstance startPlayer];
    return 0;
}

static int stopMusic(struct lua_State *state)
{
    [audioAddOnInstance stopPlayer];
    return 0;
}

static int getVolume(struct lua_State *state)
{
    //  Push the integer volume onto the Lua stack
    
    lua_pushinteger(state, [audioAddOnInstance getPlayerVolume]);
    
    //  Our function returns 1 value = volume
    
    return 1;
}

static int setVolume(struct lua_State *state)
{
    [audioAddOnInstance setPlayerVolume: lua_tonumber(state, 1)];
    return 0;
}

static int peakPowerForChannel(struct lua_State *state)
{
    //  Channel numbers are zero-indexed. A monaural signal,
    //  or the left channel of a stereo signal, has channel number 0.
    
    NSUInteger channel = lua_tonumber(state, 1);
    
    //  Push the integer power onto the Lua stack
    
    lua_pushinteger(state, [audioAddOnInstance getPeakPower: channel]);
    
    //  Our function returns 1 value = peak power
    
    return 1; 
}

static int averagePowerForChannel(struct lua_State *state)
{
    //  Channel numbers are zero-indexed. A monaural signal,
    //  or the left channel of a stereo signal, has channel number 0.
    
    NSUInteger channel = lua_tonumber(state, 1);
    
    //  Push the integer power onto the Lua stack
    
    lua_pushinteger(state, [audioAddOnInstance getAveragePower: channel]);
    
    //  Our function returns 1 value = peak power
    
    return 1;
}

#pragma mark - AVAudioPlayer Delegate

//  These Audio Player call back methods are not used in this tutorial but provided here
//  for information. There are a number of other delegate methods available. Check the
//  documentation.

- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag
{
    
}

- (void)audioPlayerDecodeErrorDidOccur:(AVAudioPlayer *)player error:(NSError *)error
{
    NSLog(@"Error decoding audio file: %@", [error localizedDescription]);
}

-(void)audioPlayerBeginInterruption:(AVAudioPlayer *)player
{
    
}

-(void)audioPlayerEndInterruption:(AVAudioPlayer *)player
{
    
}

@end

Main.lua

-- AudioDemo
--
-- Uses Cider Controls v1.6 from @Mark and @aciolino
-- make sure you add this as a Dependency
--
-- Reefwing Software (c) 2013
-- www.reefwing.com.au


function setup()
    
    displayMode(FULLSCREEN)
    setInstructionLimit(0)
    ctlFrame = Control("Audio Player", 20, HEIGHT - 600, 450, HEIGHT - 20)
    ctlFrame.background = color(181, 141, 203, 255)
    ctlFrame.textAlign = CENTER
    ctlFrame.fontSize = 24
    
    -- Initialise the Cider Controls
    
    playBtn = TextButton("Play", 70, 480, 225, 520)
    stopBtn = TextButton("Stop", 245, 480, 400, 520)
    sldVolume = Slider("Volume Control", 70, HEIGHT - 450, 400, HEIGHT - 420, 0, 100, 50)
    
    -- Initialise the Cider Volume Indicators
    
    dial = Dial("Left", 70, 780, 220, 930, 0, 100, 0)
    doughnut = Doughnut("Right", 250, 780, 400, 930, 0, 100, sldVolume.val)
    doughnut.intervals = 25
    doughnut.warm = 9
    doughnut.hot = 13
    
end

function draw()
    
    -- This sets a dark background color 
    
    background(178, 173, 173, 255)

    -- Draw the Cider Controls
    
    ctlFrame:draw()
    playBtn:draw()
    stopBtn:draw()
    sldVolume:draw()
    dial:draw()
    doughnut:draw()

    -- Update the dB Meter Dials
    --
    -- The iPad should have 2 channels, left = 0 and right = 1

    dial.val = averagePowerForChannel(0) or 0
    doughnut.val = averagePowerForChannel(1) or 0

end

function touched(touch)
    
    if sldVolume: touched(touch) then
        -- call AudioAddOn function
        setVolume(sldVolume.val)
    end
    
    if playBtn:touched(touch) then
        -- call AudioAddOn function
        playMusic()
    end
    
    if stopBtn:touched(touch) then
        -- call AudioAddOn function
        stopMusic()
    end
    
end