AVAudioRecorder不会录制以前录制和播放的IF电影

Question

我的iPhone应用程序使用"AVAudioRecorder"进行录音.它还使用"UIImagePickerController"来录制电影,使用"MPMoviePlayerController"来播放电影.

一切正常,直到我连续做三件事:

1. 使用UIImagePickerController录制电影
2. 使用MPMoviePlayerController播放录制的电影
3. 尝试使用AVAudioRecorder进行录音

当我在步骤3中调用AVAudioRecorder的"记录"方法时,它返回NO表示失败,但没有提示为什么(来到Apple!)AVAudioRecorder的audioRecorderEncodeErrorDidOccur委托方法永远不会被调用,我在设置录像机时没有收到任何其他错误.

我的第一个猜测是,电影录制/播放正在以一种阻止录音机工作的方式修改"AVAudioSession"的共享实例.但是,我手动将AVAudioSession的类别属性设置为"AVAudioSessionCategoryRecord",并且在尝试录制之前使音频会话处于活动状态.

这是我创建录音机的方法:

- (void)createAudioRecorder
{
 NSError *error = nil;
 AVAudioSession *audioSession = [AVAudioSession sharedInstance];
 [audioSession setCategory:AVAudioSessionCategoryRecord error:&error];
 if (error)
  ...
 [audioSession setActive:YES error:&error];
 if (error)
  ...

 NSMutableDictionary *settings = [[NSMutableDictionary alloc] init];

 // General Audio Format Settings 
 [settings setValue:[NSNumber numberWithInt:kAudioFormatMPEG4AAC] forKey:AVFormatIDKey];
 [settings setValue:[NSNumber numberWithFloat:44100.0] forKey:AVSampleRateKey]; 
 [settings setValue:[NSNumber numberWithInt:1] forKey:AVNumberOfChannelsKey];

 // Encoder Settings 
 [settings setValue:[NSNumber numberWithInt:AVAudioQualityMin] forKey:AVEncoderAudioQualityKey]; 
 [settings setValue:[NSNumber numberWithInt:96] forKey:AVEncoderBitRateKey]; 
 [settings setValue:[NSNumber numberWithInt:16] forKey:AVEncoderBitDepthHintKey];

 // Write the audio to a temporary file
 NSURL *tempURL = [NSURL fileURLWithPath:[NSTemporaryDirectory() stringByAppendingPathComponent:@"Recording.m4a"]];

 audioRecorder = [[AVAudioRecorder alloc] initWithURL:tempURL settings:settings error:&error];
 if (error)
  ...

 audioRecorder.delegate = self;
 if ([audioRecorder prepareToRecord] == NO)
  NSLog(@"Recorder fails to prepare!");

 [settings release];
}

这是我开始录制的方法:

- (void)startRecording
{
 if (!audioRecorder)
  [self createAudioRecorder];

 NSError *error = nil;
 [[AVAudioSession sharedInstance] setActive:YES error:&error];
 if (error)
  ...

 BOOL recording = [audioRecorder record];
 if (!recording)
  NSLog(@"Recording won't start!");
}

有没有人遇到过这个问题？

Answer 1

我遇到了同样的问题.在我解决问题之前,我的录制/播放代码是这样的:

开始录制功能

- (BOOL) startRecording {   
@try {
    NSDictionary *recordSetting = [[NSDictionary alloc] initWithObjectsAndKeys:
[NSNumber numberWithInt: kAudioFormatAppleLossless], AVFormatIDKey, [NSNumber numberWithFloat: 44100.0], AVSampleRateKey, [NSNumber numberWithInt: 1], AVNumberOfChannelsKey,  [NSNumber numberWithInt: AVAudioQualityMax], AVEncoderAudioQualityKey, nil];

        NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
        NSString *soundFilePath = [documentsPath stringByAppendingPathComponent:@"recording.caf"];

        if(audioRecorder != nil) {
            [audioRecorder stop];
            [audioRecorder release];
            audioRecorder = nil;
        }

        NSError *err = nil;
        audioRecorder = [[AVAudioRecorder alloc] initWithURL:soundFileURL settings:recordSetting error:&err];
        [soundFileURL release];
        [recordSetting release];
        if(!audioRecorder || err){
            NSLog(@"recorder initWithURL: %@ %d %@", [err domain], [err code], [[err userInfo] description]);
            return NO;
        }

        [audioRecorder peakPowerForChannel:8];
        [audioRecorder updateMeters];
        audioRecorder.meteringEnabled = YES;
        [audioRecorder record];
    }
    @catch (NSException * e) {
        return NO;
    }

    recording = YES;
    return YES;
}

停止录制功能

- (BOOL) stopRecording {
    @try {
        [audioRecorder stop];
        [audioRecorder release];
        audioRecorder = nil;

        recording = NO;
    }
    @catch (NSException * e) {
        return NO;
    }

    return YES;
}

开始播放功能

- (BOOL) startPlaying {
    @try {
        NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
        NSString *soundFilePath = [documentsPath stringByAppendingPathComponent:@"recording.caf"];      NSURL * soundFileURL = [[NSURL alloc] initFileURLWithPath: soundFilePath];
        NSError *err = nil;

        if (audioPlayer) {
            [audioPlayer release];
            audioPlayer = nil;
        }

        audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:soundFileURL error: &err];
        [soundFileURL release];
        if (!audioPlayer || err) {
            NSLog(@"recorder: %@ %d %@", [err domain], [err code], [[err userInfo] description]);
            return NO;
        }

        [audioPlayer prepareToPlay];
        [audioPlayer setDelegate: self];
        [audioPlayer play];

        playing = YES;
    }
    @catch (NSException * e) {
        return NO;
    }

    return YES;
}

停止播放功能

- (BOOL) stopPlaying {
    @try {
        [audioPlayer stop];
        [audioPlayer release];
        audioPlayer = nil;

        playing = NO;
    }
    @catch (NSException * e) {
        return NO;
    }

    return YES;
}

我在播放捕获的视频后修复了录制问题,代码如下:

- (BOOL) startRecording {   
    @try {
        AVAudioSession *session = [AVAudioSession sharedInstance];
        [session setCategory:AVAudioSessionCategoryRecord error:nil];

        // rest of the recording code is the same .
}

- (BOOL) stopRecording {
    @try {
        AVAudioSession *session = [AVAudioSession sharedInstance];
        [session setCategory:AVAudioSessionCategoryPlayback error:nil];

    // rest of the code is the same
}

- (BOOL) startPlaying {
    @try {
        AVAudioSession *session = [AVAudioSession sharedInstance];
        [session setCategory:AVAudioSessionCategoryPlayback error:nil];

    // rest of the code is the same. 
}

- (BOOL) stopPlaying {
    // There is no change in this function
}