Built-in Module audio

audio

Note: This module is obsolete, since the hardware to which it interfaces is obsolete. For audio on the Indigo or 4D/35, see built-in module al above.

This module provides rudimentary access to the audio I/O device /dev/audio on the Silicon Graphics Personal IRIS 4D/25; see audio(7). It supports the following operations:

$\begin{funcdesc}{setoutgain}{n} Sets the output gain. \iftexi \code{0 <= \var{n} < 256}. \else $0 \leq \var{n} < 256$. \fi \end{funcdesc}$

$\begin{funcdesc}{getoutgain}{} Returns the output gain. \end{funcdesc}$

$\begin{funcdesc}{setrate}{n} Sets the sampling rate: \code{1} = 32K/sec, \code{2} = 16K/sec, \code{3} = 8K/sec. \end{funcdesc}$

$\begin{funcdesc}{setduration}{n} Sets the \lq sound duration' in units of 1/100 seconds. \end{funcdesc}$

$\begin{funcdesc}{read}{n} Reads a chunk of \var{n} sampled bytes from the audio ... ...n be converted to numbers using \code{chr2num()} described below. \end{funcdesc}$

$\begin{funcdesc}{write}{buf} Writes a chunk of samples to the audio output (speaker). \end{funcdesc}$

These operations support asynchronous audio I/O:

$\begin{funcdesc}{start_recording}{n} Starts a second thread (a process with shar... ...tes from the audio device. The main thread immediately continues. \end{funcdesc}$

$\begin{funcdesc}{wait_recording}{} Waits for the second thread to finish and returns the data read. \end{funcdesc}$

$\begin{funcdesc}{stop_recording}{} Makes the second thread stop reading as soon as possible. Returns the data read so far. \end{funcdesc}$

$\begin{funcdesc}{poll_recording}{} Returns true if the second thread has finishe... ...(so \code{wait_recording()} would return the data without delay). \end{funcdesc}$

$\begin{funcdesc}{start_playing}{} \funcline{wait_playing}{} \funcline{stop_playi... ...mber of bytes actually played (not very accurate). \end{sloppypar}\end{funcdesc}$

The following operations do not affect the audio device but are implemented in C for efficiency:

$\begin{funcdesc}{amplify}{buf\, f1\, f2} Amplifies a chunk of samples by a varia... ...Resulting values that are to large to fit in a byte are clipped. \end{funcdesc}$

$\begin{funcdesc}{reverse}{buf} Returns a chunk of samples backwards. \end{funcdesc}$

$\begin{funcdesc}{add}{buf1\, buf2} Bytewise adds two chunks of samples. Bytes th... ... If one buffer is shorter, it is assumed to be padded with zeros. \end{funcdesc}$

$\begin{funcdesc}{chr2num}{buf} Converts a string of sampled bytes as returned by... ...read()} into a list containing the numeric values of the samples. \end{funcdesc}$

$\begin{funcdesc}{num2chr}{list} \begin{sloppypar} Converts a list as returned by... ...()} back to a buffer acceptable by \code{write()}. \end{sloppypar}\end{funcdesc}$