音频用什么压缩格式

我的设置给你参考下，m4a格式，音质可以说算好了，20秒40k，2秒也是40k，更长时间忘了多大了，反正比上传图片流量小很多

NSMutableDictionary* recordSetting = [NSMutableDictionary dictionaryWithObjectsAndKeys:                                              [NSNumber numberWithInt:kAudioFormatMPEG4AAC], AVFormatIDKey,                                              [NSNumber numberWithFloat:44100.0], AVSampleRateKey,                                              [NSNumber numberWithInt:1], AVNumberOfChannelsKey,                                              [NSNumber numberWithInt:AVAudioQualityMin], AVEncoderAudioQualityKey,                                              [NSNumber numberWithInt:AVAudioQualityMin], AVSampleRateConverterAudioQualityKey,                                              [NSNumber numberWithInt:8], AVLinearPCMBitDepthKey,                                              nil];