Next Previous

AudioTapProcessor/MYViewController.m

/*

     File: MYViewController.m

 Abstract: Main view controller

  Version: 1.0.1

 Disclaimer: IMPORTANT:  This Apple software is supplied to you by Apple

 Inc. ("Apple") in consideration of your agreement to the following

 terms, and your use, installation, modification or redistribution of

 this Apple software constitutes acceptance of these terms.  If you do

 not agree with these terms, please do not use, install, modify or

 redistribute this Apple software.

 In consideration of your agreement to abide by the following terms, and

 subject to these terms, Apple grants you a personal, non-exclusive

 license, under Apple's copyrights in this original Apple software (the

 "Apple Software"), to use, reproduce, modify and redistribute the Apple

 Software, with or without modifications, in source and/or binary forms;

 provided that if you redistribute the Apple Software in its entirety and

 without modifications, you must retain this notice and the following

 text and disclaimers in all such redistributions of the Apple Software.

 Neither the name, trademarks, service marks or logos of Apple Inc. may

 be used to endorse or promote products derived from the Apple Software

 without specific prior written permission from Apple.  Except as

 expressly stated in this notice, no other rights or licenses, express or

 implied, are granted by Apple herein, including but not limited to any

 patent rights that may be infringed by your derivative works or by other

 works in which the Apple Software may be incorporated.

 The Apple Software is provided by Apple on an "AS IS" basis.  APPLE

 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

 THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS

 FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND

 OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.

 IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL

 OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

 INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION,

 MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED

 AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE),

 STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE

 POSSIBILITY OF SUCH DAMAGE.

 Copyright (C) 2013 Apple Inc. All Rights Reserved.

*/

#import "MYViewController.h"

#import <AssetsLibrary/AssetsLibrary.h>

#import <AVFoundation/AVFoundation.h>

#import "MYAudioTapProcessor.h"

#import "MYPlayerView.h"

#import "MYVolumeUnitMeterView.h"

#import "MYSettingsViewController.h"

static void *MYViewControllerPlayerStatusObserverContext = &MYViewControllerPlayerStatusObserverContext;

static NSString *stringFromCMTime(CMTime time, NSString *sign);

@interface MYViewController () <MYAudioTabProcessorDelegate, MYSettingsViewControllerDelegate>

// IBOutlets

@property (weak, nonatomic) IBOutlet MYPlayerView *playerView;

@property (weak, nonatomic) IBOutlet MYVolumeUnitMeterView *leftChannelVolumeUnitMeterView;

@property (weak, nonatomic) IBOutlet MYVolumeUnitMeterView *rightChannelVolumeUnitMeterView;

@property (weak, nonatomic) IBOutlet UIButton *playPauseButton;

@property (weak, nonatomic) IBOutlet UILabel *elapsedTimeLabel;

@property (weak, nonatomic) IBOutlet UISlider *currentTimeSlider;

@property (weak, nonatomic) IBOutlet UILabel *remainingTimeLabel;

@property (weak, nonatomic) IBOutlet UIButton *settingsPopoverButton;

@property (readonly, strong, nonatomic) AVPlayer *player;

@property (readonly, strong, nonatomic) id playerTimeObserver;

@property (readonly, strong, nonatomic) id playerItemDidPlayToEndTimeObserver;

@property (readonly, strong, nonatomic) MYAudioTapProcessor *audioTapProcessor;

// IBActions

- (IBAction)togglePlayPause:(id)sender;

- (IBAction)seekToTime:(id)sender;

@end

@implementation MYViewController

- (NSURL *)sampleMovieURL

    __block NSURL *sampleMovieURL;

    static dispatch_once_t onceToken;

    dispatch_once(&onceToken, ^{

        dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);

        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{

            ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init];

            [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {

                if (group)

                    [group enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {

                        if (result && [[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypeVideo])

                            NSURL *URL = [[result defaultRepresentation] url];

                            if (URL)

                                sampleMovieURL = URL;

                                *stop = YES;

                                dispatch_semaphore_signal(semaphore);

}];

                    if (sampleMovieURL)

                        *stop = YES;

                else

                    dispatch_semaphore_signal(semaphore);

            } failureBlock:^(NSError *error) {

                dispatch_semaphore_signal(semaphore);

}];

});

        dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);

        if (!sampleMovieURL)

            UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:nil message:@"Could not find any movies in assets library to use as sample content." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];

            [alertView show];

});

    return sampleMovieURL;

#pragma mark - Properties

@synthesize player = _player;

- (AVPlayer *)player

    if (!_player)

        _player = [AVPlayer playerWithURL:[self sampleMovieURL]];

    return _player;

@synthesize audioTapProcessor = _audioTapProcessor;

- (MYAudioTapProcessor *)audioTapProcessor

    if (!_audioTapProcessor)

        AVAssetTrack *firstAudioAssetTrack;

        for (AVAssetTrack *assetTrack in self.player.currentItem.asset.tracks)

            if ([assetTrack.mediaType isEqualToString:AVMediaTypeAudio])

                firstAudioAssetTrack = assetTrack;

                break;

        if (firstAudioAssetTrack)

            _audioTapProcessor = [[MYAudioTapProcessor alloc] initWithAudioAssetTrack:firstAudioAssetTrack];

            _audioTapProcessor.delegate = self;

    return _audioTapProcessor;

@synthesize playerView;

@synthesize leftChannelVolumeUnitMeterView;

@synthesize rightChannelVolumeUnitMeterView;

@synthesize playPauseButton;

@synthesize elapsedTimeLabel;

@synthesize currentTimeSlider;

@synthesize remainingTimeLabel;

@synthesize settingsPopoverButton;

#pragma mark -

- (void)viewDidLoad

    [super viewDidLoad];

    // Attach player to player view.

    self.playerView.player = self.player;

    // Disable play pause button and current time slider (until player is ready to play).

    self.playPauseButton.enabled = NO;

    self.currentTimeSlider.enabled = NO;

    // Disable settings popover button (until audio tap is created).

    self.settingsPopoverButton.enabled = NO;

    // Start observing player's status.

    [self.player addObserver:self forKeyPath:@"status" options:(NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew) context:MYViewControllerPlayerStatusObserverContext];

    // Add player item did play to end time observer.

    _playerItemDidPlayToEndTimeObserver = [[NSNotificationCenter defaultCenter] addObserverForName:AVPlayerItemDidPlayToEndTimeNotification object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification *note) {

        if (note.object == self.player.currentItem)

            // Update play pause button.

            [self.playPauseButton setImage:[UIImage imageNamed:@"PlayButton"] forState:UIControlStateNormal];

}];

- (void)viewDidUnload

    // Remove player item did play to end time observer.

    [[NSNotificationCenter defaultCenter] removeObserver:_playerItemDidPlayToEndTimeObserver];

    _playerItemDidPlayToEndTimeObserver = nil;

    // Remove time observer for current time slider and label.

    [self.player removeTimeObserver:_playerTimeObserver];

    _playerTimeObserver = nil;

    // Stop observing player's status.

    [self.player removeObserver:self forKeyPath:@"status" context:MYViewControllerPlayerStatusObserverContext];

    // Dettach player from player view.

    self.playerView.player = nil;

    [self setPlayerView:nil];

    [self setLeftChannelVolumeUnitMeterView:nil];

    [self setRightChannelVolumeUnitMeterView:nil];

    [self setPlayPauseButton:nil];

    [self setElapsedTimeLabel:nil];

    [self setCurrentTimeSlider:nil];

    [self setRemainingTimeLabel:nil];

    [self setSettingsPopoverButton:nil];

    [super viewDidUnload];

- (void)didReceiveMemoryWarning

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation

    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {

        return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);

    } else {

        return YES;

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender

    if ([segue.identifier isEqualToString:@"ShowSettingsSegue"])

        // Setup settings view controller before it is shown.

        MYSettingsViewController *settingsViewController = (MYSettingsViewController *)((UINavigationController *)segue.destinationViewController).topViewController;

        settingsViewController.delegate = self;

        settingsViewController.enabledSwitchValue = self.audioTapProcessor.isBandpassFilterEnabled;

        settingsViewController.centerFrequencySliderValue = self.audioTapProcessor.centerFrequency;

        settingsViewController.bandwidthSliderValue = self.audioTapProcessor.bandwidth;

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context

    if (MYViewControllerPlayerStatusObserverContext == context)

        id newValue = change[NSKeyValueChangeNewKey];

        if (newValue && [newValue isKindOfClass:[NSNumber class]])

            if (AVPlayerStatusReadyToPlay == [newValue integerValue])

                CMTime duration = self.player.currentItem.duration;

                // Setup current time indicators.

                self.elapsedTimeLabel.text = stringFromCMTime(kCMTimeZero, nil);

                self.currentTimeSlider.value = 0.0f;

                self.remainingTimeLabel.text = stringFromCMTime(duration, @"-");

                // Add time observer for current time slider and label.

                __weak MYViewController *weakSelf = self; // keep retain cycle from occuring

                _playerTimeObserver = [self.player addPeriodicTimeObserverForInterval:CMTimeMake(1, 1) queue:dispatch_get_main_queue() usingBlock:^(CMTime time) {

                    // Update current time indicators.

                    weakSelf.elapsedTimeLabel.text = stringFromCMTime(time, nil);

                    weakSelf.currentTimeSlider.value = (float)(CMTimeGetSeconds(time) / CMTimeGetSeconds(duration));

                    weakSelf.remainingTimeLabel.text = stringFromCMTime(CMTimeSubtract(duration, time), @"-");

}];

                // Add audio mix with audio tap processor to current player item.

                AVAudioMix *audioMix = self.audioTapProcessor.audioMix;

                if (audioMix)

                    // Add audio mix with first audio track.

                    self.player.currentItem.audioMix = audioMix;

                    // Enable settings popover button.

                    self.settingsPopoverButton.enabled = YES;

                // Enable play pause button and current time slider.

                self.playPauseButton.enabled = YES;

                self.currentTimeSlider.enabled = YES;

    else

        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];

#pragma mark - IBActions

- (IBAction)togglePlayPause:(id)sender

    NSParameterAssert(self.player);

    if (self.player.rate == 0.0f)

        // Play from beginning when playhead is at end.

        if (CMTIME_COMPARE_INLINE(self.player.currentItem.currentTime, >=, self.player.currentItem.duration))

            [self.player.currentItem seekToTime:kCMTimeZero toleranceBefore:kCMTimeZero toleranceAfter:kCMTimeZero];

        // Start playback.

        self.player.rate = 1.0f;

        // Update play pause button.

        [self.playPauseButton setImage:[UIImage imageNamed:@"PauseButton"] forState:UIControlStateNormal];

    else

        // Stop playback.

        self.player.rate = 0.0f;

        // Update play pause button.

        [self.playPauseButton setImage:[UIImage imageNamed:@"PlayButton"] forState:UIControlStateNormal];

- (IBAction)seekToTime:(id)sender

    NSParameterAssert(self.player);

    // Seek to corresponding time.

    [self.player seekToTime:(CMTimeMultiplyByFloat64(self.player.currentItem.duration, (Float64)[(UISlider *)sender value])) toleranceBefore:kCMTimeZero toleranceAfter:kCMTimeZero];

#pragma mark - MYAudioTabProcessorDelegate

- (void)audioTabProcessor:(MYAudioTapProcessor *)audioTabProcessor hasNewLeftChannelValue:(float)leftChannelValue rightChannelValue:(float)rightChannelValue

    // Update left and right channel volume unit meter.

    self.leftChannelVolumeUnitMeterView.value = leftChannelValue;

    self.rightChannelVolumeUnitMeterView.value = rightChannelValue;

#pragma mark - MYSettingsViewControllerDelegate

- (void)settingsViewController:(MYSettingsViewController *)settingsViewController didUpdateEnabledSwitchValue:(float)switchValue

    // Forward value to audio tap processor.

    self.audioTapProcessor.enableBandpassFilter = switchValue;

- (void)settingsViewController:(MYSettingsViewController *)settingsViewController didUpdateCenterFrequencySliderValue:(float)sliderValue

    // Forward value to audio tap processor.

    self.audioTapProcessor.centerFrequency = sliderValue;

- (void)settingsViewController:(MYSettingsViewController *)settingsViewController didUpdateBandwidthSliderValue:(float)sliderValue

    // Forward value to audio tap processor.

    self.audioTapProcessor.bandwidth = sliderValue;

@end

#pragma mark - Functions

static NSString *stringFromCMTime(CMTime time, NSString *sign)

    NSString *stringFromCMTime;

    float seconds = round(CMTimeGetSeconds(time));

    int hh = (int)floorf(seconds / 3600.0f);

    int mm = (int)floorf((seconds - hh * 3600.0f) / 60.0f);

    int ss = (((int)seconds) % 60);

    if (hh > 0)

        stringFromCMTime = [NSString stringWithFormat:@"%@%02d:%02d:%02d", (sign ? sign : @""), hh, mm, ss];

    else

        stringFromCMTime = [NSString stringWithFormat:@"%@%02d:%02d", (sign ? sign : @""), mm, ss];

    return stringFromCMTime;

Next Previous