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. 用 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.