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Add some recent things to the overview docs.

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Also clean up a few other doc related bits and pieces.

Change-Id: I56714e1811e38a7225131c1d141430b49f5f509c
Reviewed-by: Jonas Rabbe <jonas.rabbe@nokia.com>
This commit is contained in:
Michael Goddard
2012-02-08 23:48:58 +10:00
committed by Qt by Nokia
parent c77e442b99
commit db781f29e0
18 changed files with 276 additions and 18 deletions
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49
doc/src/audiooverview.qdoc
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@@ -28,12 +28,15 @@
/*!
\page audiooverview.html
\title Audio Overview
\brief Audio playback and recording
\brief Audio playback, recording and processing
\section1 Audio Features
Qt Multimedia offers a range of audio classes, covering both low and
high level approaches to audio input and output.
high level approaches to audio input, output and processing. In
addition to traditional audio usage, the \l {QtAudioEngine}{Qt AudioEngine}
QML classes offers high level 3D positional audio for QML applications.
See that documentation for more information.
\section1 Audio Implementation Details
@@ -51,7 +54,16 @@ or VOIP) and high latency (like music playback). The available hardware
determines what audio outputs and inputs are available.
\section3 Push and Pull
[TBD] - description of push vs. pull mode.
The low level audio classes can operate in two modes - \c push and \c pull.
In \c pull mode, the audio device is started by giving it a QIODevice. For
an output device, the QAudioOutput class will pull data from the QIODevice
(using \l QIODevice::read()) when more audio data is required. Conversely,
for \c pull mode with QAudioInput, when audio data is available then the
data will be written directly to the QIODevice.
In \c push mode, the audio device provides a QIODevice instance that
can be written or read to as needed. Typically this results in simpler
code but more buffering, which may affect latency.
\section2 Low latency sound effects
@@ -82,12 +94,43 @@ Here is how you play a local file using C++:
You can also put files (even remote URLs) into a playlist:
\snippet doc/src/snippets/multimedia-snippets/media.cpp Audio playlist
\section2 Decoding compressed audio to memory
In some cases you may want to decode a compressed audio file and do further
processing yourself (like mix multiple samples, or some custom digital signal
processing algorithms). Qt Multimedia 5.0 offers a preliminary API for this
case - the \l QAudioDecoder class. QAudioDecoder supports decoding local files
or from a QIODevice instances.
Here's an example of decoding a local file:
\snippet doc/src/snippets/multimedia-snippets/audio.cpp Local audio decoding
Note: This API is preliminary at this time - the API may change or be
removed before the final 5.0 release. In addition, it is necessary to
add "multimedia-private" to the QT variable in your .pro file to use this class.
\snippet doc/src/snippets/multimedia-snippets/audio.cpp Audio decoder header
\section2 Recording audio to a file
For recording audio to a file, the \l {QAudioRecorder} class allows you
to compress audio data from an input device and record it.
\snippet doc/src/snippets/multimedia-snippets/media.cpp Audio recorder
\section2 Monitoring audio data during playback or recording
The \l QAudioProbe class allows you to monitor audio data being played or
recorded in the higher level classes like \l QMediaPlayer, \l QCamera and
\l QAudioRecorder. After creating your high level class, you can simply
set the source of the probe to your class, and receive audio buffers as they
are processed. This is useful for several audio processing tasks, particularly
for visualization or adjusting gain. You cannot modify the buffers, and
they may arrive at a slightly different time than the media pipeline
processes them.
Here's an example of installing a probe during recording:
\snippet doc/src/snippets/multimedia-snippets/media.cpp Audio probe
\section1 Examples
There are both C++ and QML examples available.