Refactored pcm buffer



git-svn-id: svn+ssh://svn.code.sf.net/p/cmusphinx/code/trunk/sphinxbase@12527 94700074-3cef-4d97-a70e-9c8c206c02f5
Absolute threshold for VAD, don't process very quiet segments



git-svn-id: svn+ssh://svn.code.sf.net/p/cmusphinx/code/trunk/sphinxbase@12528 94700074-3cef-4d97-a70e-9c8c206c02f5