rtMicrophoneHandler, inherited from rtDataHandler, is the main
class for microphone handling. It is the only one that has to be instancied
by programmers. Its work is to initialise the microphone, and codes incoming
audio streams into the outgoing buffer of data handler.
Audio encoding is made by an instance of rtMicrophoneCoder that
belongs to a rtMicrophoneHandler.
Please note that rtDataHandler standard block handling method is
ignored and that the execute(void*) method is overloaded (since
no incoming stream rtDataStream exists).
First of all, rtMicrophoneCoder is doing a basic microphone
calibration. When done, it enters in a normal audio encoding mode that
consists in listening for noise, ignore silences except when they reflect
a end of speech stream (EOS), and chain either sound blocks
(ST_SOUND data stream block type) or EOS block
(ST_EOS type).
The silenceBlocksForEOS parameter contains the number of silences
corresponding to the end of speech/stream information.
Others parameters handle microphone hard configuration :
acqFrequency (in Hz, default 8000), sampleSize
(is the basic word's number of bits), blockSize
(depending on underlaying hardware, this is the byte number that are
readen from device in a raw; commonly 64), and blockNumber
is the number of raw device blocks that'll be in encoded a
sound block buffer.