音频##
常用的音频API######
- SystemSoundServices
- AVAudioPlayer
- MPMusicPlayerController
- AVAudioRecorder
- OpenAL
- AudioUnits
其中最常用的还是 SystemSoundServices 和 AVAudioPlayer
System Sound Services######
C形式接口，属于AudioToolBox框架，这个框架可以将比较短的声音注册到 system sound服务上。被注册到system sound服务上的声音称之为 system sounds。比如其中的播放API AudioServicesPlaySystemSound()，但是只可以播放一些简单的音频文件，此方法它只适合播放一些很小的提示或者是警告音，并有很多限制：
1> 长度小于30秒的Core Audio Format (.caf), Waveform audio (.wav), 或者 Audio Interchange File (.aiff)
2> 调用后立即播放，并且声音的进度无法控制
3> 没有循环播放和立体声控制
SystemSound常用的方法######
- AudioServicesCreateSystemSoundID 从URL创建声音
- AydioServicesDisposeSystemSoundID 播放完成时删除声音
- AudioServicesAddSystemSoundCompletion 播放完成时回调
- AudioServicesRemoveSystemSoundCompletion 播放完成时删除回调
- AudioServicesPlaySystemSound 播放
Demo示例(首先要把push.wav托到项目中去)：
导入 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:@"播放结束"
delegate:nil
cancelButtonTitle:@"确定"
otherButtonTitles:nil,
nil];
[alert show];
[alert release];
// 震动设备
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文件放到项目中
NSURL *url = [NSURL fileURLWithPath:path];
// 创建声音
OSStatus error = AudioServicesCreateSystemSoundID((CFURLRef)url, &_soundID);
// 增加回调 simpleSoundFinishCompletion
AudioServicesAddSystemSoundCompletion(self.soundID, nil, nil, finishCompletion, nil);
if (error) {
UIAlertView *alert = [[UIAlertView alloc]
initWithTitle:@"提示"
message:@"加载声音文件错误!"
delegate:nil
cancelButtonTitle:@"确定"
otherButtonTitles:nil,
nil];
[alert show];
[alert release];
} else {
AudioServicesPlaySystemSound(self.soundID);
}
}
@end
AVAudioPlayer######
AVAudioPlayer属于AVFoundation框架，对于压缩过Audio文件，或者超过30秒的音频文件，可以使用AVAudioPlayer类，这个类定义在AVFoundation framework中，因此要导入 AVFoundation framwork, 并且 #import <AVFoundation/AVFoundation.h>
下面通过一个录音和播放录音的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];
// 初始化录音文件的路径
NSString *soundFilePath = [NSTemporaryDirectory() stringByAppendingPathComponent:@"sound.caf"];
self.soundURL = [NSURL fileURLWithPath:soundFilePath];
// 建立音频会话
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:@"录制" 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 状态
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryRecord error:nil];
// 设置属性
NSDictionary *recordSettings =
[[NSDictionary alloc] initWithObjectsAndKeys:
[NSNumber numberWithFloat: 44100.0], AVSampleRateKey,
[NSNumber numberWithInt: kAudioFormatAppleLossless], AVFormatIDKey,
[NSNumber numberWithInt: 1], AVNumberOfChannelsKey,
[NSNumber numberWithInt: AVAudioQualityMax], AVEncoderAudioQualityKey,
nil];
// 创建 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:@"录制" 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];
}
