iOS　录音功能的实现

这两天也调了一下ios的录音，原文链接：http://www.iphoneam.com/blog/index.php?title=using-the-iphone-to-record-audio-a-guide&more=1&c=1&tb=1&pb=1

这里ios的录音功能主要依靠AVFoundation.framework与CoreAudio.framework来实现



在工程内添加这两个framework

我这里给工程命名audio_text

在生成的audio_textViewController.h里的代码如下

[cpp] view
plaincopyprint?

#import <UIKit/UIKit.h>

#import <AVFoundation/AVFoundation.h>

#import <CoreAudio/CoreAudioTypes.h>

@interface audio_textViewController : UIViewController {

IBOutlet UIButton *bthStart;

IBOutlet UIButton *bthPlay;

IBOutlet UITextField *freq;

IBOutlet UITextField *value;

IBOutlet UIActivityIndicatorView *actSpinner;

BOOL toggle;

//Variable setup for access in the class

NSURL *recordedTmpFile;

AVAudioRecorder *recorder;

NSError *error;

}

@property (nonatomic,retain)IBOutlet UIActivityIndicatorView *actSpinner;

@property (nonatomic,retain)IBOutlet UIButton *bthStart;

@property (nonatomic,retain)IBOutlet UIButton *bthPlay;

-(IBAction)start_button_pressed;

-(IBAction)play_button_pressed;

@end

audio_textViewController.m

[cpp] view
plaincopyprint?

#import "audio_textViewController.h"

@implementation audio_textViewController

- (void)viewDidLoad {

[super viewDidLoad];

//Start the toggle in true mode.

toggle = YES;

bthPlay.hidden = YES;

//Instanciate an instance of the AVAudioSession object.

AVAudioSession * audioSession = [AVAudioSession sharedInstance];

//Setup the audioSession for playback and record.

//We could just use record and then switch it to playback leter, but

//since we are going to do both lets set it up once.

[audioSession setCategory:AVAudioSessionCategoryPlayAndRecord error: &error];

//Activate the session

[audioSession setActive:YES error: &error];

}

/*

// The designated initializer. Override to perform setup that is required before the view is loaded.

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {

self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];

if (self) {

// Custom initialization

}

return self;

}

*/

/*

// Implement loadView to create a view hierarchy programmatically, without using a nib.

- (void)loadView {

}

*/

/*

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.

- (void)viewDidLoad {

[super viewDidLoad];

}

*/

/*

// Override to allow orientations other than the default portrait orientation.

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {

// Return YES for supported orientations

return (interfaceOrientation == UIInterfaceOrientationPortrait);

}

*/

- (IBAction) start_button_pressed{

if(toggle)

{

toggle = NO;

[actSpinner startAnimating];

[bthStart setTitle:@"停" forState: UIControlStateNormal ];

bthPlay.enabled = toggle;

bthPlay.hidden = !toggle;

//Begin the recording session.

//Error handling removed. Please add to your own code.

//Setup the dictionary object with all the recording settings that this

//Recording sessoin will use

//Its not clear to me which of these are required and which are the bare minimum.

//This is a good resource: http://www.totodotnet.net/tag/avaudiorecorder/
NSMutableDictionary* recordSetting = [[NSMutableDictionary alloc] init];

[recordSetting setValue :[NSNumber numberWithInt:kAudioFormatAppleIMA4] forKey:AVFormatIDKey];

[recordSetting setValue:[NSNumber numberWithFloat:[freq.text floatValue]] forKey:AVSampleRateKey];

[recordSetting setValue:[NSNumber numberWithInt: [value.text intValue]] forKey:AVNumberOfChannelsKey];

//Now that we have our settings we are going to instanciate an instance of our recorder instance.

//Generate a temp file for use by the recording.

//This sample was one I found online and seems to be a good choice for making a tmp file that

//will not overwrite an existing one.

//I know this is a mess of collapsed things into 1 call. I can break it out if need be.

recordedTmpFile = [NSURL fileURLWithPath:[NSTemporaryDirectory() stringByAppendingPathComponent: [NSString stringWithFormat: @"%.0f.%@", [NSDate timeIntervalSinceReferenceDate] * 1000.0, @"caf"]]];

NSLog(@"Using File called: %@",recordedTmpFile);

//Setup the recorder to use this file and record to it.

recorder = [[ AVAudioRecorder alloc] initWithURL:recordedTmpFile settings:recordSetting error:&error];

//Use the recorder to start the recording.

//Im not sure why we set the delegate to self yet.

//Found this in antother example, but Im fuzzy on this still.

[recorder setDelegate:self];

//We call this to start the recording process and initialize

//the subsstems so that when we actually say "record" it starts right away.

[recorder prepareToRecord];

//Start the actual Recording

[recorder record];

//There is an optional method for doing the recording for a limited time see

//[recorder recordForDuration:(NSTimeInterval) 10]

}

else

{

toggle = YES;

[actSpinner stopAnimating];

[bthStart setTitle:@"开始录音" forState:UIControlStateNormal ];

bthPlay.enabled = toggle;

bthPlay.hidden = !toggle;

NSLog(@"Using File called: %@",recordedTmpFile);

//Stop the recorder.

[recorder stop];

}

}

- (void)didReceiveMemoryWarning {

// Releases the view if it doesn't have a superview.

[super didReceiveMemoryWarning];

// Release any cached data, images, etc that aren't in use.

}

-(IBAction) play_button_pressed{

//The play button was pressed...

//Setup the AVAudioPlayer to play the file that we just recorded.

AVAudioPlayer * avPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:recordedTmpFile error:&error];

[avPlayer prepareToPlay];

[avPlayer play];

}

- (void)viewDidUnload {

// Release any retained subviews of the main view.

// e.g. self.myOutlet = nil;

//Clean up the temp file.

NSFileManager * fm = [NSFileManager defaultManager];

[fm removeItemAtPath:[recordedTmpFile path] error:&error];

//Call the dealloc on the remaining objects.

[recorder dealloc];

recorder = nil;

recordedTmpFile = nil;

}

- (void)dealloc {

[super dealloc];

}

@end

最后在interface builder里面绘制好界面，如



设置下按键的属性



基本就ok了，可以开始录音了。

BUG解决
但是大家要注意一个貌似是ios5.0之后引入的bug，就是当你录制音频的时候启动时间往往会比较慢，大概需要3－－5秒的时间吧，这种现象尤其在播放的时候立刻切换到录制的时候非常明显。

具体的原因我也不是很清楚，感觉应该是更底层的一些bug。目前我的解决方案是这样的。
1.在音频队列的初始化方法中加入代码

OSStatus error = AudioSessionInitialize(NULL, NULL, NULL, NULL);

UInt32 category
= kAudioSessionCategory_PlayAndRecord;

error = AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(category),
&category);

AudioSessionAddPropertyListener(kAudioSessionProperty_AudioRouteChange, NULL, self);

UInt32 inputAvailable = 0;

UInt32 size = sizeof(inputAvailable);

AudioSessionGetProperty(kAudioSessionProperty_AudioInputAvailable, &size, &inputAvailable);

AudioSessionAddPropertyListener(kAudioSessionProperty_AudioInputAvailable, NULL, self);

AudioSessionSetActive(true);

2.在录制声音开始的时候先把播放声音stop，加入

UInt32 category
= kAudioSessionCategory_PlayAndRecord;

AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(category),
&category);

这样做应该会让你的录制启动速度显著加快的。