音频录制
http://www.code4app.com/thread-29537-1-1.html
音频录音
https://blog.csdn.net/koocui/article/details/51889066
变声处理
https://blog.csdn.net/it_yangjing/article/details/51622454
转码配置，lame
https://www.jianshu.com/p/ba2e95d8ab0b
https://www.jianshu.com/p/62899e829e45
音频资料
http://www.cnblogs.com/iOS-mt/p/4268532.html
音频资料，比较全
https://www.jianshu.com/p/c70c9add3655
音频采样率
https://blog.csdn.net/ameyume/article/details/7746161
深入-------
AudioUnit，AudioQueue
http://www.cnblogs.com/iOS-mt/p/4268532.html
audiounit总结
https://www.jianshu.com/p/f859640fcb33
回声抑制使用AudioUnit
实现录音和耳返
https://www.jianshu.com/p/53006a9d76c5
https://www.jianshu.com/p/f741a1ed9912
