音頻##
常用的音頻API######
- SystemSoundServices
- AVAudioPlayer
- MPMusicPlayerController
- AVAudioRecorder
- OpenAL
- AudioUnits
其中最常用的還是 SystemSoundServices 和 AVAudioPlayer
System Sound Services######
C形式接口，屬于AudioToolBox框架，這個框架可以將比較短的聲音注冊到 system sound服務上。被注冊到system sound服務上的聲音稱之為 system sounds。比如其中的播放API AudioServicesPlaySystemSound()，但是只可以播放一些簡單的音頻文件，此方法它只適合播放一些很小的提示或者是警告音，并有很多限制：
1> 長度小于30秒的Core Audio Format (.caf), Waveform audio (.wav), 或者 Audio Interchange File (.aiff)
2> 調用后立即播放，并且聲音的進度無法控制
3> 沒有循環播放和立體聲控制
SystemSound常用的方法######
- AudioServicesCreateSystemSoundID 從URL創建聲音
- AydioServicesDisposeSystemSoundID 播放完成時刪除聲音
- AudioServicesAddSystemSoundCompletion 播放完成時回調
- AudioServicesRemoveSystemSoundCompletion 播放完成時刪除回調
- AudioServicesPlaySystemSound 播放
Demo示例(首先要把push.wav托到項目中去)：
導入 AudioToolbox.framework 并且
#import <AudioToolbox/AudioToolbox.h>
@interface RootViewController ()
@property(nonatomic) SystemSoundID soundID;
@end
@implementation RootViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(20, 40, self.view.bounds.size.width - 40, 40)];
label.backgroundColor = [UIColor darkGrayColor];
label.textAlignment = NSTextAlignmentCenter;
label.text = @"System Sound Services 方式";
label.textColor = [UIColor whiteColor];
[self.view addSubview:label];
UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
CGRect frame = label.frame;
frame.origin.y = CGRectGetMaxY(label.frame) + 10.0;
button.frame = frame;
[button setTitle:@"播放" forState:UIControlStateNormal];
[button addTarget:self action:@selector(systemSoundPlay:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:button];
}
static void finishCompletion()
{
UIAlertView *alert = [[UIAlertView alloc]
initWithTitle:@"提示"
message:@"播放結束"
delegate:nil
cancelButtonTitle:@"確定"
otherButtonTitles:nil,
nil];
[alert show];
[alert release];
// 震動設備
AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);
/**
enum
{
#if TARGET_OS_IPHONE
kSystemSoundID_Vibrate = 0x00000FFF
#else
kSystemSoundID_UserPreferredAlert = 0x00001000,
kSystemSoundID_FlashScreen = 0x00000FFE,
// this has been renamed to be consistent
kUserPreferredAlert = kSystemSoundID_UserPreferredAlert
#endif
};
*/
}
- (void)systemSoundPlay:(UIButton *)button
{
// 初始化URL
NSString *path = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"push.wav"]; // 注意，首先要把push.wav文件放到項目中
NSURL *url = [NSURL fileURLWithPath:path];
// 創建聲音
OSStatus error = AudioServicesCreateSystemSoundID((CFURLRef)url, &_soundID);
// 增加回調 simpleSoundFinishCompletion
AudioServicesAddSystemSoundCompletion(self.soundID, nil, nil, finishCompletion, nil);
if (error) {
UIAlertView *alert = [[UIAlertView alloc]
initWithTitle:@"提示"
message:@"加載聲音文件錯誤!"
delegate:nil
cancelButtonTitle:@"確定"
otherButtonTitles:nil,
nil];
[alert show];
[alert release];
} else {
AudioServicesPlaySystemSound(self.soundID);
}
}
@end
AVAudioPlayer######
AVAudioPlayer屬于AVFoundation框架，對于壓縮過Audio文件，或者超過30秒的音頻文件，可以使用AVAudioPlayer類，這個類定義在AVFoundation framework中，因此要導入 AVFoundation framwork, 并且 #import <AVFoundation/AVFoundation.h>
下面通過一個錄音和播放錄音的Demo示例展示：
#import "RootViewController.h"
#import <AVFoundation/AVFoundation.h>
@interface RootViewController () <AVAudioPlayerDelegate>
@property (nonatomic, retain) NSURL *soundURL;
@property (nonatomic, retain) UIButton *recordBtn;
@property (nonatomic, retain) UIButton *playBtn;
@property (nonatomic, retain) AVAudioRecorder *recorder;
@property (nonatomic, retain) AVAudioPlayer *player;
@end
@implementation RootViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
[self initUI];
// 初始化錄音文件的路徑
NSString *soundFilePath = [NSTemporaryDirectory() stringByAppendingPathComponent:@"sound.caf"];
self.soundURL = [NSURL fileURLWithPath:soundFilePath];
// 建立音頻會話
AVAudioSession *audioSession = [AVAudioSession sharedInstance];
[[NSNotificationCenter defaultCenter] addObserver: self
selector: @selector(handleInterruption:)
name: AVAudioSessionInterruptionNotification
object: audioSession];
[audioSession setActive:YES error:nil];
/**
AudioSession ...
*/
}
- (void)handleInterruption:(NSNotification *)notification
{
NSLog(@"%s", __func__);
}
- (void)initUI
{
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(20, 40, self.view.bounds.size.width - 40, 40)];
label.backgroundColor = [UIColor darkGrayColor];
label.textAlignment = NSTextAlignmentCenter;
label.text = @"AVAudioRecorder/AVAudioPlayer";
label.textColor = [UIColor whiteColor];
[self.view addSubview:label];
self.recordBtn = [UIButton buttonWithType:UIButtonTypeSystem];
CGRect frame = label.frame;
frame.origin.y = CGRectGetMaxY(label.frame) + 10.0;
frame.size.width = frame.size.width / 2.0;
self.recordBtn.frame = frame;
[self.recordBtn setTitle:@"錄制" forState:UIControlStateNormal];
[self.recordBtn addTarget:self action:@selector(record:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:self.recordBtn];
self.playBtn = [UIButton buttonWithType:UIButtonTypeSystem];
frame.origin.x += frame.size.width;
self.playBtn.frame = frame;
[self.playBtn setTitle:@"播放" forState:UIControlStateNormal];
[self.playBtn addTarget:self action:@selector(play:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:self.playBtn];
}
- (void)record:(UIButton *)button
{
if (self.recorder.isRecording) {
[self stopRecord];
} else {
[self beginRecord];
}
}
- (void)play:(UIButton *)button
{
if (self.recorder.isRecording) {
[self stopRecord];
}
if (self.player.isPlaying) {
[self stopPlay];
} else {
[self beginPlay];
}
}
- (void)beginRecord
{
// 更新 AVAudioSession 狀態
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryRecord error:nil];
// 設置屬性
NSDictionary *recordSettings =
[[NSDictionary alloc] initWithObjectsAndKeys:
[NSNumber numberWithFloat: 44100.0], AVSampleRateKey,
[NSNumber numberWithInt: kAudioFormatAppleLossless], AVFormatIDKey,
[NSNumber numberWithInt: 1], AVNumberOfChannelsKey,
[NSNumber numberWithInt: AVAudioQualityMax], AVEncoderAudioQualityKey,
nil];
// 創建 AVAudioRecorder
AVAudioRecorder *recorder = [[AVAudioRecorder alloc] initWithURL:self.soundURL
settings:recordSettings
error:nil];
self.recorder = recorder;
[recorder release];
[self.recorder prepareToRecord];
[self.recorder record];
[self.recordBtn setTitle:@"停止" forState:UIControlStateNormal];
}
- (void)stopRecord
{
[self.recorder stop];
[self.recordBtn setTitle:@"錄制" forState:UIControlStateNormal];
[[AVAudioSession sharedInstance] setActive:NO error:nil];
}
- (void)beginPlay
{
NSError *error = nil;
AVAudioSession *session = [AVAudioSession sharedInstance];
[session setCategory:AVAudioSessionCategoryPlayback error:&error];
if (error) {
NSLog(@"error occured: %@", error.userInfo);
[self stopPlay];
return ;
}
AVAudioPlayer *player = [[AVAudioPlayer alloc] initWithContentsOfURL:self.soundURL error:&error];
self.player = player;
if (error) {
NSLog(@"error occured: %@", error.userInfo);
return ;
}
[self.player setDelegate:self];
[self.player prepareToPlay];
[self.playBtn setTitle:@"停止" forState:UIControlStateNormal];
}
- (void)stopPlay
{
[self.player stop];
[self.playBtn setTitle:@"播放" forState:UIControlStateNormal];
}
#pragma mark - <AVAudioPlayerDelegate>
- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag
{}
#pragma mark - dealloc
- (void)dealloc
{
[_soundURL release];
[_recordBtn release];
[_playBtn release];
[_recorder release];
[_player release];
[super dealloc];
}
