@c Copyright (C) 1996-2019 Kurt Hornik
@c
@c This file is part of Octave.
@c
@c Octave is free software: you can redistribute it and/or modify it
@c under the terms of the GNU General Public License as published by
@c the Free Software Foundation, either version 3 of the License, or
@c (at your option) any later version.
@c
@c Octave is distributed in the hope that it will be useful, but
@c WITHOUT ANY WARRANTY; without even the implied warranty of
@c MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
@c GNU General Public License for more details.
@c
@c You should have received a copy of the GNU General Public License
@c along with Octave; see the file COPYING.  If not, see
@c <https://www.gnu.org/licenses/>.

@c Written by Kurt Hornik <Kurt.Hornik@wu-wien.ac.at> on 1996/05/14

@node Audio Processing
@chapter Audio Processing

@menu
* Audio File Utilities::
* Audio Device Information::
* Audio Player::
* Audio Recorder::
* Audio Data Processing::
@end menu

@node Audio File Utilities
@section Audio File Utilities

The following functions allow you to read, write and retrieve
information about audio files.  Various formats are supported including
wav, flac and ogg vorbis.

@DOCSTRING(audioinfo)

@DOCSTRING(audioread)

@DOCSTRING(audiowrite)

@DOCSTRING(audioformats)

@node Audio Device Information
@section Audio Device Information

@DOCSTRING(audiodevinfo)

@node Audio Player
@section Audio Player

The following methods are used to create and use audioplayer
objects.  These objects can be used to play back audio data stored in
Octave matrices and arrays.  The audioplayer object supports playback
from various devices available to the system, blocking and non-blocking
playback, convenient pausing and resuming and much more.

@DOCSTRING(@audioplayer/audioplayer)

@menu
* Playback::
* Player Properties::
@end menu

@node Playback
@subsection Playback

The following methods are used to control player playback.

@DOCSTRING(@audioplayer/play)

@DOCSTRING(@audioplayer/playblocking)

@DOCSTRING(@audioplayer/pause)

@DOCSTRING(@audioplayer/resume)

@DOCSTRING(@audioplayer/stop)

@DOCSTRING(@audioplayer/isplaying)

@node Player Properties
@subsection Properties

The remaining couple of methods are used to get and set various
properties of the audioplayer object.

@DOCSTRING(@audioplayer/get)

@DOCSTRING(@audioplayer/set)

@node Audio Recorder
@section Audio Recorder

The following methods are used to create and use audiorecorder
objects.  These objects can be used to record audio data from various
devices available to the system.  You can use convenient methods to
retrieve that data or audioplayer objects created from that
data.  Methods for blocking and non-blocking recording, pausing and
resuming recording and much more is available.

@DOCSTRING(@audiorecorder/audiorecorder)

@menu
* Recording::
* Data Retrieval::
* Recorder Properties::
@end menu

@node Recording
@subsection Recording

The following methods control the recording process.

@DOCSTRING(@audiorecorder/record)

@DOCSTRING(@audiorecorder/recordblocking)

@DOCSTRING(@audiorecorder/pause)

@DOCSTRING(@audiorecorder/resume)

@DOCSTRING(@audiorecorder/stop)

@DOCSTRING(@audiorecorder/isrecording)

@node Data Retrieval
@subsection Data Retrieval

The following methods allow you to retrieve recorded audio data in
various ways.

@DOCSTRING(@audiorecorder/getaudiodata)

@DOCSTRING(@audiorecorder/getplayer)

@DOCSTRING(@audiorecorder/play)

@node Recorder Properties
@subsection Properties

The remaining two methods allow you to read or alter the properties of
audiorecorder objects.

@DOCSTRING(@audiorecorder/get)

@DOCSTRING(@audiorecorder/set)

@node Audio Data Processing
@section Audio Data Processing

Octave provides a few functions for dealing with audio data.  An audio
`sample' is a single output value from an A/D converter, i.e., a small
integer number (usually 8 or 16 bits), and audio data is just a series
of such samples.  It can be characterized by three parameters: the
sampling rate (measured in samples per second or Hz, e.g., 8000 or
44100), the number of bits per sample (e.g., 8 or 16), and the number of
channels (1 for mono, 2 for stereo, etc.).

There are many different formats for representing such data.  Currently,
only the two most popular, @emph{linear encoding} and @emph{mu-law
encoding}, are supported by Octave.  There is an excellent FAQ on audio
formats by @nospell{Guido van Rossum} @email{guido@@cwi.nl} which can be
found at any FAQ ftp site, in particular in the directory
@file{/pub/usenet/news.answers/audio-fmts} of the archive site
@code{rtfm.mit.edu}.

Octave simply treats audio data as vectors of samples (non-mono data are
not supported yet).  It is assumed that audio files using linear
encoding have one of the extensions @file{lin} or @file{raw}, and that
files holding data in mu-law encoding end in @file{au}, @file{mu}, or
@file{snd}.

@DOCSTRING(lin2mu)

@DOCSTRING(mu2lin)

@DOCSTRING(record)

@DOCSTRING(sound)

@DOCSTRING(soundsc)
