AVAudioRecorder file too big

I am recording audio using AVAudioRecorder and the file is too big. Like 20 seconds, comes out to be 1.2mb? How c开发者_高级运维an I make it smaller? Thanks.

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This is the best way I found, you can use it too:

NSMutableDictionary *settings = [[NSMutableDictionary alloc] initWithCapacity:0];

[settings setValue :[NSNumber numberWithInt:kAudioFormatMPEG4AAC] forKey:AVFormatIDKey];//格式
[settings setValue:[NSNumber numberWithFloat:8000.0] forKey:AVSampleRateKey]; //采样8000次
[settings setValue:[NSNumber numberWithInt: 1] forKey:AVNumberOfChannelsKey];//声道
[settings setValue :[NSNumber numberWithInt:8] forKey:AVLinearPCMBitDepthKey];//位深度
[settings setValue :[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsBigEndianKey];
[settings setValue :[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsFloatKey];
//Encoder
[settings setValue :[NSNumber numberWithInt:12000] forKey:AVEncoderBitRateKey];//采样率
[settings setValue :[NSNumber numberWithInt:8] forKey:AVEncoderBitDepthHintKey];//位深度
[settings setValue :[NSNumber numberWithInt:8] forKey:AVEncoderBitRatePerChannelKey];//声道采样率
[settings setValue :AVAudioQualityMin           forKey:AVEncoderAudioQualityKey];//编码质量

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Try using a different format and/or quality setting. Something like this should be a pretty small file:

NSDictionary *recordSettings =
    [[NSDictionary alloc] initWithObjectsAndKeys:
     [NSNumber numberWithFloat: 44100.0], AVSampleRateKey,
     [NSNumber numberWithInt: kAudioFormatAppleIMA4], AVFormatIDKey,
     [NSNumber numberWithInt: 1], AVNumberOfChannelsKey,
     [NSNumber numberWithInt: AVAudioQualityMedium],
     AVEncoderAudioQualityKey,
     nil];

    AVAudioRecorder *newRecorder =
    [[AVAudioRecorder alloc] initWithURL: myURL
                                settings: recordSettings
                                   error: nil];

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The size of the recorded audio file depends on the following factors. There are other factors too. But following would be worth noting.
1) Sample Rate
A 22050Hz sample rate will produce a much smaller file than a 44000Hz sample rate

2) Channels
Stereo output(2 channels) will produce twice the size of the file of that of a mono (1 channel)

3) Bit Rate
Bits used per sample.

You will need to come up with a setting that is best suitable for you so that it doesn't compromise on the quality as well as the size.