[bufferData, underflow, overflow] = Datapixx(‘ReadMicrophoneBuffer’, numFrames [, bufferAddress]);
Upload audio input data from a Datapixx internal acquisition buffer to the local
-“numFrames” is the number of acquired frames to upload. In a streaming
application, numFrames should not exceed newBufferFrames returned by
GetMicrophoneStatus. It may be possible to reduce dynamic memory allocation
overhead by matching numFrames to the size of an existing bufferData output
-“bufferAddress” is the byte address in Datapixx RAM where the buffered data can
be found. If this argument is not provided, it will take on the value of
bufferBaseAddress passed to the last call to SetMicrophoneSchedule. Specifying a
bufferAddress of -1 will cause data to be streamed from the buffer which was
defined in the last call to SetMicrophoneSchedule.
-“bufferData” is a 2D matrix of acquired audio input data in the range -1 to +1.
The first row of the matrix contains data for the left ear, and the second row
contains data for the right ear. A non-stereo dataset will only have a single
row. ReadMicrophoneBuffer assumes that the number of channels to return equals
the number of channels specified by lrMode in the last call to
-“underflow” or “overflow” are set to 1 if streaming calls to
ReadMicrophoneBuffer read data too quickly or too slowly. If bufferAddress is
passed a value of -1, then ReadMicrophoneBuffer is streaming continuous
acquisition data from a circular buffer. Streaming acquisition must ensure that
the uploaded data frame always remains behind the acquisition frame, without
allowing acquired data to overflow the acquisition buffer. The newBufferFrames
field returned by GetMicrophoneStatus indicates the maximum number of frames
which can be read by ReadMicrophoneBuffer. If more than this number of frames is
read, an underflow occurs and there will be errors in the acquired data. If the
streaming data is not read quickly enough, and newBufferFrames exceeds the
buffer size (numBufferFrames passed to SetMicrophoneSchedule)) then an overflow
has occurred, causing data to be lost. In addition to returning
underflow/overflow flags, the numStreamUnderflows/numStreamOverflows fields
returned by GetMicrophoneStatus will be incremented.
See DatapixxMicrophone*Demo files for examples.