Classes/MyViewController.m

/*
        File: MyViewController.m
    Abstract: >The main view controller of this app.
     Version: 1.0.3
    
    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) 2014 Apple Inc. All Rights Reserved.
    
*/
 
#import "MyViewController.h"
 
extern OSStatus DoConvertFile(CFURLRef sourceURL, CFURLRef destinationURL, OSType outputFormat, Float64 outputSampleRate);
 
#define kTransitionDuration 0.75
 
#pragma mark-
 
static Boolean IsAACEncoderAvailable(void)
{
    Boolean isAvailable = false;
 
    // get an array of AudioClassDescriptions for all installed encoders for the given format 
    // the specifier is the format that we are interested in - this is 'aac ' in our case
    UInt32 encoderSpecifier = kAudioFormatMPEG4AAC;
    UInt32 size;
 
    OSStatus result = AudioFormatGetPropertyInfo(kAudioFormatProperty_Encoders, sizeof(encoderSpecifier), &encoderSpecifier, &size);
    if (result) { printf("AudioFormatGetPropertyInfo kAudioFormatProperty_Encoders result %lu %4.4s\n", result, (char*)&result); return false; }
 
    UInt32 numEncoders = size / sizeof(AudioClassDescription);
    AudioClassDescription encoderDescriptions[numEncoders];
    
    result = AudioFormatGetProperty(kAudioFormatProperty_Encoders, sizeof(encoderSpecifier), &encoderSpecifier, &size, encoderDescriptions);
    if (result) { printf("AudioFormatGetProperty kAudioFormatProperty_Encoders result %lu %4.4s\n", result, (char*)&result); return false; }
    
    printf("Number of AAC encoders available: %lu\n", numEncoders);
    
    // with iOS 7.0 AAC software encode is always available
    // older devices like the iPhone 4s also have a slower/less flexible hardware encoded for supporting AAC encode on older systems
    // newer devices may not have a hardware AAC encoder at all but a faster more flexible software AAC encoder
    // as long as one of these encoders is present we can convert to AAC
    // if both are available you may choose to which one to prefer via the AudioConverterNewSpecific() API
    for (UInt32 i=0; i < numEncoders; ++i) {
        if (encoderDescriptions[i].mSubType == kAudioFormatMPEG4AAC && encoderDescriptions[i].mManufacturer == kAppleHardwareAudioCodecManufacturer) {
            printf("Hardware encoder available\n");
            isAvailable = true;
        }
        if (encoderDescriptions[i].mSubType == kAudioFormatMPEG4AAC && encoderDescriptions[i].mManufacturer == kAppleSoftwareAudioCodecManufacturer) {
            printf("Software encoder available\n");
            isAvailable = true;
        }
    }
        
    return isAvailable;
}
 
static void UpdateFormatInfo(UILabel *inLabel, CFURLRef inFileURL)
{
    AudioFileID fileID;
    
    OSStatus result = AudioFileOpenURL(inFileURL, kAudioFileReadPermission, 0, &fileID);
    if (noErr == result) {
        CAStreamBasicDescription asbd;
        UInt32 size = sizeof(asbd);
        result = AudioFileGetProperty(fileID, kAudioFilePropertyDataFormat, &size, &asbd);
        if (noErr == result) {
            char formatID[5]; 
            CFStringRef lastPathComponent = CFURLCopyLastPathComponent(inFileURL);
            *(UInt32 *)formatID = CFSwapInt32HostToBig(asbd.mFormatID);
    
            inLabel.text = [NSString stringWithFormat: @"%@ %4.4s %6.0f Hz (%ld ch.)", lastPathComponent, formatID, asbd.mSampleRate, asbd.NumberChannels(), nil];
            CFRelease(lastPathComponent);
        } else {
            printf("AudioFileGetProperty kAudioFilePropertyDataFormat result %lu %4.4s\n", result, (char*)&result);
        }
            
        AudioFileClose(fileID);
    } else {
        printf("AudioFileOpenURL failed! result %lu %4.4s\n", result, (char*)&result);
    }
}
 
#pragma mark-
 
@implementation MyViewController
 
@synthesize instructionsView, webView, contentView, outputFormatSelector, outputSampleRateSelector, startButton, activityIndicator, flipButton, doneButton;
 
- (void)dealloc
{
    [instructionsView release];
    [webView release];
    [contentView release];
    
    [fileInfo release];
    
    [outputFormatSelector release];
    [outputSampleRateSelector release];
    
    [startButton release];
    [activityIndicator release];
    
    [flipButton release];
    [doneButton release];
    
    [destinationFilePath release];
    CFRelease(sourceURL);
    CFRelease(destinationURL);
    
    [super dealloc];
}
 
- (void)viewDidLoad
{   
    // create the URLs we'll use for source and destination
    NSString *source = [[NSBundle mainBundle] pathForResource:@"sourcePCM" ofType:@"aif"];
    sourceURL = CFURLCreateWithFileSystemPath(kCFAllocatorDefault, (CFStringRef)source, kCFURLPOSIXPathStyle, false);
    
    NSArray  *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    destinationFilePath = [[NSString alloc] initWithFormat: @"%@/output.caf", documentsDirectory];
    destinationURL = CFURLCreateWithFileSystemPath(kCFAllocatorDefault, (CFStringRef)destinationFilePath, kCFURLPOSIXPathStyle, false);
 
    // load up the info text
    NSString *infoSouceFile = [[NSBundle mainBundle] pathForResource:@"info" ofType:@"html"];
    NSString *infoText = [NSString stringWithContentsOfFile:infoSouceFile encoding:NSUTF8StringEncoding error:nil];
    [self.webView loadHTMLString:infoText baseURL:nil];
    self.webView.backgroundColor = [UIColor whiteColor];
        
    // set up start button
    UIImage *greenImage = [[UIImage imageNamed:@"green_button.png"] stretchableImageWithLeftCapWidth:12.0 topCapHeight:0.0];
    UIImage *redImage = [[UIImage imageNamed:@"red_button.png"] stretchableImageWithLeftCapWidth:12.0 topCapHeight:0.0];
    
    [startButton setBackgroundImage:greenImage forState:UIControlStateNormal];
    [startButton setBackgroundImage:redImage forState:UIControlStateDisabled];
    
    // add the subview
    [self.view addSubview:contentView];
    
    // add our custom flip buttons as the nav bars custom right view
    UIButton* infoButton = [UIButton buttonWithType:UIButtonTypeInfoLight];
    [infoButton addTarget:self action:@selector(flipAction:) forControlEvents:UIControlEventTouchUpInside];
    
    flipButton = [[UIBarButtonItem alloc] initWithCustomView:infoButton];
    self.navigationItem.rightBarButtonItem = flipButton;
    
    // create our done button as the nav bar's custom right view for the flipped view (used later)
    doneButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(flipAction:)];
    
    // default output format
    // sample rate of 0 indicates source file sample rate
    outputFormat = kAudioFormatAppleLossless;
    sampleRate = 0;
    
    // can we encode to AAC?
    if (IsAACEncoderAvailable()) {
        [self.outputFormatSelector setEnabled:YES forSegmentAtIndex:0];
    } else {
        // even though not enabled in IB, this segment will still be enabled
        // if not specifically turned off here which we'll assume is a bug
        [self.outputFormatSelector setEnabled:NO forSegmentAtIndex:0];
    }
    
    UpdateFormatInfo(fileInfo, sourceURL);
 
}
 
- (void)didReceiveMemoryWarning
{
    // Invoke super's implementation to do the Right Thing, but also release the input controller since we can do that  
    // In practice this is unlikely to be used in this application, and it would be of little benefit,
    // but the principle is the important thing.
    
    [super didReceiveMemoryWarning];
}
 
#pragma mark- Actions
 
- (void)flipAction:(id)sender
{
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:NULL];
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:kTransitionDuration];
    
    [UIView setAnimationTransition:([self.contentView superview] ? UIViewAnimationTransitionFlipFromLeft : UIViewAnimationTransitionFlipFromRight)
                                    forView:self.view
                                    cache:YES];
                                    
    if ([self.instructionsView superview]) {
        [self.instructionsView removeFromSuperview];
        [self.view addSubview:contentView];
    } else {
        [self.contentView removeFromSuperview];
        [self.view addSubview:instructionsView];
    }
    
    [UIView commitAnimations];
    
    // adjust our done/info buttons accordingly
    if ([instructionsView superview]) {
        self.navigationItem.rightBarButtonItem = doneButton;
    } else {
        self.navigationItem.rightBarButtonItem = flipButton;
    }
}
 
- (IBAction)convertButtonPressed:(id)sender
{
    NSError *error = nil;
    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryAudioProcessing error:&error];
    if (error) {
        printf("Setting the AVAudioSessionCategoryAudioProcessing Category failed! %ld\n", (long)error.code);
        
        return;
    } 
 
    [self.startButton setTitle:@"Converting..." forState:UIControlStateDisabled];
    [startButton setEnabled:NO];
    
    [self.activityIndicator startAnimating];
    
    // run audio file code in a background thread
    [self performSelectorInBackground:(@selector(convertAudio)) withObject:nil];
}
 
- (IBAction)segmentedControllerValueChanged:(id)sender
{
    switch ([sender tag]) {
    case 0:
        switch ([sender selectedSegmentIndex]) {
        case 0:
            outputFormat = kAudioFormatMPEG4AAC;
            [self.outputSampleRateSelector setEnabled:YES forSegmentAtIndex:0];
            [self.outputSampleRateSelector setEnabled:YES forSegmentAtIndex:1];
            [self.outputSampleRateSelector setEnabled:YES forSegmentAtIndex:2];
            [self.outputSampleRateSelector setEnabled:YES forSegmentAtIndex:3];
            break;
        case 1:
            outputFormat = kAudioFormatAppleIMA4;
            [self.outputSampleRateSelector setEnabled:YES forSegmentAtIndex:0];
            [self.outputSampleRateSelector setEnabled:YES forSegmentAtIndex:1];
            [self.outputSampleRateSelector setEnabled:YES forSegmentAtIndex:2];
            [self.outputSampleRateSelector setEnabled:YES forSegmentAtIndex:3];
            break;
        case 2:
            // iLBC sample rate is 8K
            outputFormat = kAudioFormatiLBC;
            sampleRate = 8000.0;
            [self.outputSampleRateSelector setSelectedSegmentIndex:2];
            [self.outputSampleRateSelector setEnabled:NO forSegmentAtIndex:0];
            [self.outputSampleRateSelector setEnabled:NO forSegmentAtIndex:1];
            [self.outputSampleRateSelector setEnabled:NO forSegmentAtIndex:3];
            break;
        case 3:
            outputFormat = kAudioFormatAppleLossless;
            [self.outputSampleRateSelector setEnabled:YES forSegmentAtIndex:0];
            [self.outputSampleRateSelector setEnabled:YES forSegmentAtIndex:1];
            [self.outputSampleRateSelector setEnabled:YES forSegmentAtIndex:2];
            [self.outputSampleRateSelector setEnabled:YES forSegmentAtIndex:3];
            break;
        }
        break;
    case 1:
        switch ([sender selectedSegmentIndex]) {
        case 0:
            sampleRate = 44100.0;
            break;
        case 1:
            sampleRate = 22050.0;
            break;
        case 2:
            sampleRate = 8000.0;
            break;
        case 3:
            sampleRate = 0;
            break;
        }
        break;
    }
}
 
#pragma mark- AVAudioPlayer
 
- (void)updateUI
{
    [startButton setEnabled:YES];
    UpdateFormatInfo(fileInfo, sourceURL);
}
 
- (void)audioPlayerDecodeErrorDidOccur:(AVAudioPlayer *)player error:(NSError *)error
{
    NSLog(@"audioPlayerDecodeErrorDidOccur %@", [error localizedDescription]);
    [self audioPlayerDidFinishPlaying:player successfully:false];
}
 
- (void)audioPlayerBeginInterruption:(AVAudioPlayer *)player
{
    printf("Session interrupted! --- audioPlayerBeginInterruption ---\n");
    
    // if the player was interrupted during playback we don't continue
    [self audioPlayerDidFinishPlaying:player successfully:true];
}
 
- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag
{
    if (flag == NO) NSLog(@"Playback finished unsuccessfully!");
    
    printf("audioPlayerDidFinishPlaying\n");
    
    [player setDelegate:nil];
    [player release];
    
    [self updateUI];
}
 
- (void)playAudio
{
    printf("playAudio\n");
    
    UpdateFormatInfo(fileInfo, destinationURL);
    [self.startButton setTitle:@"Playing Output File..." forState:UIControlStateDisabled];
    
    // set category back to something that will allow us to play audio since AVAudioSessionCategoryAudioProcessing will not
    NSError *error = nil;
    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:&error];
    if (error) {
        printf("Setting the AVAudioSessionCategoryPlayback Category failed! %ld\n", (long)error.code);
        
        [self updateUI];
        
        return;
    } 
    
    // play the result
    AVAudioPlayer *player = [[AVAudioPlayer alloc] initWithContentsOfURL:(NSURL *)destinationURL error:&error];
    if (nil == player) {
        printf("AVAudioPlayer alloc failed! %ld\n", (long)error.code);
        
        [self updateUI];
        
        return;
    } 
 
    [player setDelegate:self];
    [player play];
}
 
#pragma mark- ExtAudioFile
 
- (void)convertAudio
{    
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
 
    OSStatus error = DoConvertFile(sourceURL, destinationURL, outputFormat, sampleRate);
    
    [self.activityIndicator stopAnimating];
    
    if (error) {
        // delete output file if it exists since an error was returned during the conversion process
        if ([[NSFileManager defaultManager] fileExistsAtPath:destinationFilePath]) {
            [[NSFileManager defaultManager] removeItemAtPath:destinationFilePath error:nil];
        }
        
        printf("DoConvertFile failed! %ld\n", error);
        [self performSelectorOnMainThread:(@selector(updateUI)) withObject:nil waitUntilDone:NO];
    } else {        
        [self performSelectorOnMainThread:(@selector(playAudio)) withObject:nil waitUntilDone:NO];
    }
    
    [pool release];
}
 
@end