AVAudio 的最佳麦克风录音设置是什么？答案

【问题标题】：What is the best microphone recording settings for AVAudio?AVAudio 的最佳麦克风录音设置是什么？
【发布时间】：2014-04-27 13:19:19
【问题描述】：

所以我有当前的代码：

- (void)viewDidLoad
{
    [super viewDidLoad];
    //for recording audio
    _stopButton.enabled = NO;
    _playButton.hidden = true;

    NSArray *dirPaths;
    NSString *docsDir;

    dirPaths = NSSearchPathForDirectoriesInDomains(
                                                   NSDocumentDirectory, NSUserDomainMask, YES);
    docsDir = dirPaths[0];

    NSString *soundFilePath = [docsDir
                               stringByAppendingPathComponent:@"recording.caf"];

    NSURL *soundFileURL = [NSURL fileURLWithPath:soundFilePath];

    NSDictionary *recordSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                    [NSNumber numberWithInt:kAudioFormatMPEG4AAC], AVFormatIDKey,
                                    [NSNumber numberWithFloat:44100.0], AVSampleRateKey,
                                    [NSNumber numberWithInt:1], AVNumberOfChannelsKey,
                                    [NSNumber numberWithInt:AVAudioQualityHigh], AVSampleRateConverterAudioQualityKey,
                                    [NSNumber numberWithInt:128000], AVEncoderBitRateKey,
                                    [NSNumber numberWithInt:16], AVEncoderBitDepthHintKey,
                                    nil];

    NSError *error = nil;

    AVAudioSession *audioSession = [AVAudioSession sharedInstance];
    [audioSession setCategory:AVAudioSessionCategoryPlayAndRecord
                        error:nil];

    _audioRecorder = [[AVAudioRecorder alloc]
                      initWithURL:soundFileURL
                      settings:recordSettings
                      error:&error];

    if (error)
    {
        NSLog(@"error: %@", [error localizedDescription]);
    } else {
        [_audioRecorder prepareToRecord];
    }
    //----------------------------
    //end

}

还有玩家：

- (IBAction)playAudio:(id)sender {
    [_playButton setEnabled:NO];
    if (!_audioRecorder.recording)
    {
        _stopButton.enabled = YES;
        _recordButton.enabled = NO;

        NSError *error;

        _audioPlayer = [[AVAudioPlayer alloc]
                        initWithContentsOfURL:_audioRecorder.url
                        error:&error];
        _audioPlayer.volume = 5;
        _audioPlayer.delegate = self;

        if (error)
            NSLog(@"Error: %@",
                  [error localizedDescription]);
        else
            [_audioPlayer play];
    }else{
        NSLog(@"errormax");
    }
}

我在5 有_audioPlayer.volume，因为如果再低一点，你就几乎看不到它。但是在那个音量下，它看起来和听起来都非常失真。为什么它听起来不像“语音备忘录”，它以合理的音量播放而不会失真？

什么是最好的质量设置？

【问题讨论】：

在AVAudioPlayer.h: @property float volume; /* The volume for the sound. The nominal range is from 0.0 to 1.0. */

标签： ios iphone objective-c avaudiorecorder

【解决方案1】：

我个人更喜欢 PCM 编码，我使用它的质量更好。

尝试：

NSDictionary *recordSettings = 
[NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:kAudioFormatLinearPCM], AVFormatIDKey,
[NSNumber numberWithFloat:44100.0], AVSampleRateKey,
[NSNumber numberWithInt:2], AVNumberOfChannelsKey,
[NSNumber numberWithInt:16], AVLinearPCMBitDepthKey,
[NSNumber numberWithBool:NO], AVLinearPCMIsBigEndianKey,
[NSNumber numberWithBool:NO], AVLinearPCMIsFloatKey,
nil];

或使其更具可读性：

NSDictionary * recordSetting;
recordSetting = [[NSMutableDictionary alloc] init];
[recordSetting setValue :[NSNumber numberWithInt:kAudioFormatLinearPCM] forKey:AVFormatIDKey];
[recordSetting setValue:[NSNumber numberWithFloat:44100.0] forKey:AVSampleRateKey];
[recordSetting setValue:[NSNumber numberWithInt: 2] forKey:AVNumberOfChannelsKey];
[recordSetting setValue :[NSNumber numberWithInt:16] forKey:AVLinearPCMBitDepthKey];
[recordSetting setValue :[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsBigEndianKey];
[recordSetting setValue :[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsFloatKey];

像这样调整你的函数：

- (IBAction)playAudio:(id)sender {
    [_playButton setEnabled:NO];
    if (!_audioRecorder.recording)
    {
        _stopButton.enabled = YES;
        _recordButton.enabled = NO;

        //force the session to play to come out of speakers!
        UInt32 sessionCategory = kAudioSessionCategory_MediaPlayback;
        AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(sessionCategory), &sessionCategory);
        UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker;
        AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute,sizeof (audioRouteOverride),&audioRouteOverride);

        NSError *error;

        _audioPlayer = [[AVAudioPlayer alloc]
                        initWithContentsOfURL:_audioRecorder.url
                        error:&error];
        _audioPlayer.delegate = self;
        [_audioPlayer prepareToPlay];

        if (error)
            NSLog(@"Error: %@",
                  [error localizedDescription]);
        else
            [_audioPlayer play];
    }else{
        NSLog(@"errormax");
    }
}

【讨论】：

非常感谢。虽然@meda 播放仍然很安静
哦，所以问题是播放声音，而不是录音？ @马克西米利安
是的。我认为这是由于录音质量。但这似乎与_audioPlayer.volume有关？
@Maximilian，我好久没做这个了，如果你真的担心，请查看stackoverflow.com/a/21684014/1880431;)
@meda - 是否可以一起录制和播放。我正在通过蓝牙从蓝牙耳机录制，并且能够在 iphone 扬声器上播放，但在停止录制后。我想同时做。你说什么？

【解决方案2】：

这是因为音频会话类别“AVAudioSessionCategoryPlayAndRecord”。除非您明确更改 overrideOutputAudioPort，否则它始终在接收器中播放音频。您可能必须为 AVAudioSessionRouteChangeNotification 添加侦听器才能根据您的输出更改类别。无论如何，为什么会让人头疼，只需在开始录制之前使用 AVAudioSessionCategoryRecord 并在开始播放器之前使用 AVAudioSessionCategoryPlayback。

//播放器

 newPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:fileURL error:nil];

NSError *setCategoryError = nil;
[audioSession setCategory: AVAudioSessionCategoryPlayback error: &setCategoryError];

//录音机

newRecorder = [[AVAudioRecorder alloc]initWithURL:fileURL settings:recordSettings error:&error];

NSError *setCategoryError = nil;
[audioSession setCategory: AVAudioSessionCategoryRecord error: &setCategoryError];

【讨论】：