Audio Signal Processing using Directshow(ISampleGrabber)
https://social.msdn.microsoft.com/Forums/windowsdesktop/en-US/8998e02d-b31b-4603-84d0-aa2d89002613/audio-signal-processing-using-directshowisamplegrabber?forum=windowsdirectshowdevelopment
http://blog.youkuaiyun.com/kathywp/article/details/2747 (介绍在BufferCB中判断捕捉的是否是视频数据)