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摄制音频

更新时间: 2014-01-05 02:34:21 责任编辑: Author_N1

 

录制音频

想要在ios设备上录制音频,可以使用AVAudioRecorder类,确保你已经将CoreAudio.framework 库添加到目标文件中

AV框架中的AVAudioRecorder类使得在iOS中录制音频变得很简单。开始录制音频需要提供一些参数给AVAudioRecorder实例的initWithURL:settings:error:方法: 

保存录音文件的URL 

文件的URL是一个本地URL.AV框架会根据URL的扩展名来决定录制文件的音频格式。所以要仔细选择扩展名。 

在采样之前和过程中使用的settings 

包括采样率、频道以及其他音频录制器开始录音的信息。Setting是一个dictionary对象。 

初始化错误发生时保存到error 变量中。 

你可以在出现异常的情况下得到这个实例中的值。 

initWithURL:settings:error: 方法的setting参数很有意思。很多值都可以保存在这个setting字典里,但是在本节中我们只讨论一些最重要的: 

AVFormatIDKey 

录音的格式。可能的值有: 

kAudioFormatLinearPCM 

kAudioFormatAppleLossless 

AVSampleRateKey 

录制音频的采样率。 

AVNumberOfChannelsKey 

录制音频的频道编号。 

AVEncoderAudioQualityKey 

录制音频的质量,可能的值有: 

AVAudioQualityMin 

AVAudioQualityLow 

AVAudioQualityMedium 

AVAudioQualityHigh 

AVAudioQualityMax 

掌握了所有这些信息后,我们可以开始写一个可以录制音频文件然后用AVAudioPlayer播放的程序。我们要做的具体事情是: 

1. Apple Lossless 格式录制音频。 

2. 把录制的音频文件用Recording.m4a文件名保存到程序的Documents目录中。 

3. 在录音开始10秒后停止录制并且立刻开始播放录制的音频。 

代码:

头文件:

#import <UIKit/UIKit.h>
#import <CoreAudio/CoreAudioTypes.h>
#import <AVFoundation/AVFoundation.h>

@interface ViewController : UIViewController<AVAudioPlayerDelegate,AVAudioRecorderDelegate>
@property(nonatomic, strong)AVAudioRecorder *audioRecorder;
@property(nonatomic, strong)AVAudioPlayer *audioPlayer;
-(NSString *)audioRecordingPath;
-(NSString *)audioRecordingSettings;
@end

实现文件:

//
//  ViewController.m
//  录制音频
//
//  Created by Rio.King on 13-11-2.
//  Copyright (c) 2013年 Rio.King. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
	
    NSError *error = nil;
    NSString *pathAsString = [self audioRecordingPath];
    NSURL *audioRecordingURL = [NSURL fileURLWithPath:pathAsString];
    self.audioRecorder = [[AVAudioRecorder alloc] initWithURL:audioRecordingURL settings:[self audioRecordingSettings] error:&error];
    if (self.audioRecorder != nil) {
        self.audioRecorder.delegate = self;
        /*prepare the recorder and then start the recording*/
        if ([self.audioRecorder prepareToRecord] && [self.audioRecorder record]) {
            NSLog(@"Successfully started to record.");
            /*after five seconds, let's stop the recording process*/
            [self performSelector:@selector(stopRecordingOnAudioRecorder:) withObject:self.audioRecorder afterDelay:10.0f];
        }else{
            NSLog(@"Failed to record.");
            self.audioRecorder = nil;
        }
    }else{
        NSLog(@"failed to create an instance of the audio recorder.");
    }
}

-(NSString *)audioRecordingPath{
    NSString *result = nil;
    NSArray *folders = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsFolder = [folders objectAtIndex:0];
    result = [documentsFolder stringByAppendingPathComponent:@"Recording.m4a"];
    return result;
}

- (NSDictionary *) audioRecordingSettings{
    NSDictionary *result = nil;
    /* Let's prepare the audio recorder options in the dictionary.
     Later we will use this dictionary to instantiate an audio
     recorder of type AVAudioRecorder */
    NSMutableDictionary *settings = [[NSMutableDictionary alloc] init];
    [settings
     setValue:[NSNumber numberWithInteger:kAudioFormatAppleLossless]
     forKey:AVFormatIDKey];
    [settings
     setValue:[NSNumber numberWithFloat:44100.0f]
     forKey:AVSampleRateKey];
    [settings
     setValue:[NSNumber numberWithInteger:1]
     forKey:AVNumberOfChannelsKey];
    [settings
     setValue:[NSNumber numberWithInteger:AVAudioQualityLow]
     forKey:AVEncoderAudioQualityKey];
    result = [NSDictionary dictionaryWithDictionary:settings];
    return result;
}


- (void) stopRecordingOnAudioRecorder:(AVAudioRecorder *)paramRecorder{
    /* Just stop the audio recorder here */
    [paramRecorder stop];
}


- (void)audioRecorderDidFinishRecording:(AVAudioRecorder *)recorder
                           successfully:(BOOL)flag{
    if (flag){
        NSLog(@"Successfully stopped the audio recording process.");
        /* Let's try to retrieve the data for the recorded file */
        NSError *playbackError = nil;
        NSError *readingError = nil;
        NSData *fileData =
        [NSData dataWithContentsOfFile:[self audioRecordingPath]
                               options:NSDataReadingMapped
                                 error:&readingError];
        /* Form an audio player and make it play the recorded data */
        self.audioPlayer = [[AVAudioPlayer alloc] initWithData:fileData
                                                         error:&playbackError];
        /* Could we instantiate the audio player? */
        if (self.audioPlayer != nil){
            self.audioPlayer.delegate = self;
            /* Prepare to play and start playing */
            if ([self.audioPlayer prepareToPlay] &&
                [self.audioPlayer play]){
                NSLog(@"Started playing the recorded audio.");
            } else {
                NSLog(@"Could not play the audio.");
            }
        } else {
            NSLog(@"Failed to create an audio player.");
        }
    } else {
        NSLog(@"Stopping the audio recording failed.");
    }
    /* Here we don't need the audio recorder anymore */
    self.audioRecorder = nil;
}

- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player
                       successfully:(BOOL)flag{
    if (flag){
        NSLog(@"Audio player stopped correctly.");
    } else {
        NSLog(@"Audio player did not stop correctly.");
    }
    if ([player isEqual:self.audioPlayer]){
        self.audioPlayer = nil;
    } else {
        /* This is not the player */
    }
}


- (void)audioPlayerBeginInterruption:(AVAudioPlayer *)player{
    /* The audio session has been deactivated here */
}
- (void)audioPlayerEndInterruption:(AVAudioPlayer *)player
                         withFlags:(NSUInteger)flags{
    if (flags == AVAudioSessionInterruptionFlags_ShouldResume){
        [player play];
    }
}



#pragma mark -处理音频录制过程中的中断
- (void)audioRecorderBeginInterruption:(AVAudioRecorder *)recorder{
    NSLog(@"Recording process is interrupted");
}
- (void)audioRecorderEndInterruption:(AVAudioRecorder *)recorder
                           withFlags:(NSUInteger)flags{
    if (flags == AVAudioSessionInterruptionFlags_ShouldResume){
        NSLog(@"Resuming the recording...");
        [recorder record];
    }
}




- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

运行结果:

2013-11-02 21:01:52.144 录制音频[1786:a0b] Successfully started to record.

2013-11-02 21:02:02.146 录制音频[1786:a0b] Successfully stopped the audio recording process.

2013-11-02 21:02:02.160 录制音频[1786:a0b] Started playing the recorded audio.

2013-11-02 21:02:12.128 录制音频[1786:a0b] Audio player stopped correctly.



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