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如何以 iLBC 格式录制音频？我从 Question # 1010343获得了一些帮助，并实现了以下代码：

NSMutableDictionary *recordSetting = [[NSMutableDictionary alloc] initWithCapacity:10];        
[recordSetting setValue:[NSNumber numberWithInt:kAudioFormatAppleIMA4] forKey:AVFormatIDKey];
//  [recordSetting setValue:[NSNumber numberWithInt:kAudioFormatMPEG4AAC] forKey:AVFormatIDKey];  //  doesn't work:  no error, but no sound
//  [recordSetting setValue:[NSNumber numberWithInt:kAudioFormatiLBC] forKey:AVFormatIDKey];  //  doesn't work:  no error, but not sound
[recordSetting setValue:[NSNumber numberWithFloat:44100.0] forKey:AVSampleRateKey];
[recordSetting setValue:[NSNumber numberWithInt: 2] forKey:AVNumberOfChannelsKey];
[recordSetting setObject:[NSNumber numberWithInt:12800] forKey:AVEncoderBitRateKey];
[recordSetting setObject:[NSNumber numberWithInt:16] forKey:AVLinearPCMBitDepthKey];
[recordSetting setObject:[NSNumber numberWithInt: AVAudioQualityHigh] forKey: AVEncoderAudioQualityKey];
recorder = [[AVAudioRecorder alloc] initWithURL:audioFile settings:recordSetting error: &avError ];
[recorder setDelegate:self];
[recorder recordForDuration:(NSTimeInterval) secLeft];
[recorder record];

像上面一样，它工作正常。好录音。轻松播放。您注意到其他格式已被注释掉。如果我尝试其中任何一个，我什么都得不到。我想要更小的文件，并根据 Question # 7279643提供以下有价值的信息：

Here are the results for few encoding supported by iPhone:
Size of audio file of duration 10 sec.
   kAudioFormatMPEG4AAC :      164 kB
   kAudioFormatAppleLossless : 430 kB
   kAudioFormatAppleIMA4 :     475 kB
   kAudioFormatULaw :          889 kB
   kAudioFormatALaw :          889 KB

我应该能够在 iLBC 中录制。但如果我尝试，我什么也得不到。当我使用 IMA4 格式以外的格式时，我在录制或播放时是否需要更改其他内容？

这是我的播放代码：

NSError     *avError;
AVAudioSession *audioSession = [AVAudioSession sharedInstance];
[audioSession setCategory:AVAudioSessionCategoryPlayback error:&avError];
[audioSession setActive:YES error:&avError];
if( !avError ) {
    if( [audioPlayer isPlaying] ) {
        [audioPlayer stop ];
    }
    while( ![audioPlayer isPlaying] ) {
        AVAudioPlayer *player = [[AVAudioPlayer alloc] initWithContentsOfURL:audioFile  error:nil];
        self.audioPlayer = player;
        self.audioPlayer.numberOfLoops = 0;
        [audioPlayer prepareToPlay];
        [audioPlayer play];
    }
} else {
    NSLog(@"Playback Error: %@", avError );
}
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1 回答 1

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通过删除修复它：

[recordSetting setValue:[NSNumber numberWithFloat:44100.0]forKey:AVSampleRateKey]; 
[recordSetting setValue:[NSNumber numberWithInt: 2] forKey:AVNumberOfChannelsKey]

我猜它们与 iLBC 默认值冲突。

于 2017-03-04T12:33:33.237 回答