Add some recent things to the overview docs.

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

Change-Id: I56714e1811e38a7225131c1d141430b49f5f509c
Reviewed-by: Jonas Rabbe <jonas.rabbe@nokia.com>

doc/config/qtmultimedia_doc.pri

@@ -43,4 +43,5 @@ OTHER_FILES += \
     doc/src/audiooverview.qdoc \
     doc/src/radiooverview.qdoc \
     doc/src/videooverview.qdoc \
+    doc/src/audioengineoverview.qdoc \
     doc/src/plugins/qml-multimedia.qdoc

doc/src/audioengineoverview.qdoc

@@ -0,0 +1,71 @@
+/****************************************************************************
+**
+** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:FDL$
+** GNU Free Documentation License
+** Alternatively, this file may be used under the terms of the GNU Free
+** Documentation License version 1.3 as published by the Free Software
+** Foundation and appearing in the file included in the packaging of
+** this file.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms
+** and conditions contained in a signed written agreement between you
+** and Nokia.
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+\page audioengineoverview.html
+\title QtAudioEngine Overview
+\brief 3D Positional Audio
+
+\section1 QtAudioEngine features
+
+Qt Multimedia includes the \c QtAudioEngine QML module for
+providing 3D positional audio.
+
+These element can be accessed through importing the
+\bold{QtAudioEngine 1.0} module.
+
+\qml
+import QtQuick 2.0
+import QtAudioEngine 1.0
+
+AudioEngine {
+// ...
+\endqml
+
+\section1 Examples
+\list
+    \o \l {AudioEngine Example}{Audio Engine}
+\endlist
+
+\section1 Reference Documentation
+
+\section2 QML Elements
+
+\list
+    \o \l AudioEngine
+    \o \l AudioSample
+    \o \l AudioCategory
+    \o \l Sound
+    \o \l SoundInstance
+    \o \l PlayVariation
+    \o \l AudioListener
+    \o \l AttenuationModelLinear
+    \o \l AttenuationModelInverse
+
+\endlist
+
+*/

doc/src/audiooverview.qdoc

@@ -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.

doc/src/multimedia.qdoc

@@ -47,6 +47,9 @@ Qt Multimedia offers APIs for doing many multimedia related tasks:
 \o Record audio and compress it
 \o Tune and listen to radio stations, and receive radio program information
 \o Use a camera, including viewfinder, image capture, and movie recording
+\o Play 3D positional audio
+\o Decode audio media files into memory for processing
+\o Accessing video frames or audio buffers as they are played or recorded
 \endlist
 
 \section2 Multimedia Components

doc/src/snippets/multimedia-snippets/audio.cpp

@@ -47,6 +47,11 @@
 #include "qaudiodeviceinfo.h"
 #include "qaudioinput.h"
 #include "qaudiooutput.h"
+#include "qaudioprobe.h"
+
+//! [Audio decoder header]
+#include "qaudiodecoder_p.h"
+//! [Audio decoder header]
 
 class AudioInputExample : public QObject {
     Q_OBJECT
@@ -208,3 +213,34 @@ void AudioDeviceInfo()
         qDebug() << "Device name: " << deviceInfo.deviceName();
     //! [Dumping audio formats]
 }
+
+class AudioDecodingExample : public QObject {
+    Q_OBJECT
+public:
+    void decode();
+
+public Q_SLOTS:
+    void stateChanged(QAudio::State newState);
+    void readBuffer();
+};
+
+void AudioDecodingExample::decode()
+{
+    //! [Local audio decoding]
+    QAudioFormat desiredFormat;
+    desiredFormat.setChannelCount(2);
+    desiredFormat.setCodec("audio/x-raw");
+    desiredFormat.setSampleType(QAudioFormat::UnSignedInt);
+    desiredFormat.setSampleRate(48000);
+    desiredFormat.setSampleSize(16);
+
+    QAudioDecoder *decoder = new QAudioDecoder(this);
+    decoder->setAudioFormat(desiredFormat);
+    decoder->setSourceFilename("level1.mp3");
+
+    connect(decoder, SIGNAL(bufferReady()), this, SLOT(readBuffer()));
+    decoder->start();
+
+    // Now wait for bufferReady() signal and call decoder->read()
+    //! [Local audio decoding]
+}

doc/src/snippets/multimedia-snippets/media.cpp

@@ -52,6 +52,10 @@
 #include "qvideowidget.h"
 #include "qcameraimagecapture.h"
 #include "qcamera.h"
+#include "qcameraviewfinder.h"
+#include "qaudioprobe.h"
+#include "qaudiorecorder.h"
+#include "qvideoprobe.h"
 
 class MediaExample : public QObject {
     Q_OBJECT
@@ -60,8 +64,11 @@ class MediaExample : public QObject {
     void MediaPlayer();
     void RadioTuna();
     void MediaRecorder();
+    void AudioRecorder();
     void EncoderSettings();
     void ImageEncoderSettings();
+    void AudioProbe();
+    void VideoProbe();
 
 private:
     // Common naming
@@ -73,9 +80,14 @@ private:
     QMediaContent video;
     QMediaRecorder *recorder;
     QCamera *camera;
+    QCameraViewfinder *viewfinder;
     QCameraImageCapture *imageCapture;
     QString fileName;
     QRadioTuner *radio;
+    QAudioRecorder *audioRecorder;
+    QAudioProbe *audioProbe;
+    QVideoProbe *videoProbe;
+
     QMediaContent image1;
     QMediaContent image2;
     QMediaContent image3;
@@ -182,7 +194,6 @@ void MediaExample::MediaPlayer()
 void MediaExample::MediaRecorder()
 {
     //! [Media recorder]
-    // Audio only recording
     recorder = new QMediaRecorder(camera);
 
     QAudioEncoderSettings audioSettings;
@@ -194,8 +205,10 @@ void MediaExample::MediaRecorder()
     recorder->setOutputLocation(QUrl::fromLocalFile(fileName));
     recorder->record();
     //! [Media recorder]
+}
 
-#if 0
+void MediaExample::AudioRecorder()
+{
     //! [Audio recorder]
     audioRecorder = new QAudioRecorder;
 
@@ -221,7 +234,6 @@ void MediaExample::MediaRecorder()
 
     audioRecorder->setAudioInput(selectedInput);
     //! [Audio recorder endpoints]
-#endif
 }
 
 void MediaExample::RadioTuna()
@@ -238,4 +250,59 @@ void MediaExample::RadioTuna()
     //! [Radio tuner]
 }
 
+void MediaExample::AudioProbe()
+{
+    //! [Audio probe]
+    audioRecorder = new QAudioRecorder;
+
+    QAudioEncoderSettings audioSettings;
+    audioSettings.setCodec("audio/amr");
+    audioSettings.setQuality(QtMultimedia::HighQuality);
+
+    audioRecorder->setEncodingSettings(audioSettings);
+
+    audioRecorder->setOutputLocation(QUrl::fromLocalFile("test.amr"));
+
+    audioProbe = new QAudioProbe(this);
+    if (audioProbe->setSource(audioRecorder)) {
+        // Probing succeeded, audioProbe->isValid() should be true.
+        connect(audioProbe, SIGNAL(audioBufferProbed(QAudioBuffer)),
+                this, SLOT(calculateLevel(QAudioBuffer)));
+    }
+
+    audioRecorder->record();
+    // Now audio buffers being recorded should be signaled
+    // by the probe, so we can do things like calculating the
+    // audio power level, or performing a frequency transform
+    //! [Audio probe]
+}
+
+void MediaExample::VideoProbe()
+{
+    //! [Video probe]
+    camera = new QCamera;
+    viewfinder = new QCameraViewfinder();
+    camera->setViewfinder(viewfinder);
+
+    camera->setCaptureMode(QCamera::CaptureVideo);
+
+    videoProbe = new QVideoProbe(this);
+
+    if (videoProbe->setSource(camera)) {
+        // Probing succeeded, videoProbe->isValid() should be true.
+        connect(videoProbe, SIGNAL(videoFrameProbed(QVideoFrame)),
+                this, SLOT(detectBarcodes(QVideoFrame)));
+    }
+
+    camera->start();
+    // Viewfinder frames should now also be emitted by
+    // the video probe, even in still image capture mode.
+    // Another alternative is to install the probe on a
+    // QMediaRecorder connected to the camera to get the
+    // recorded frames, if they are different from the
+    // viewfinder frames.
+
+    //! [Video probe]
+}
+
 

doc/src/snippets/multimedia-snippets/multimedia-snippets.pro

@@ -11,7 +11,7 @@ INCLUDEPATH += ../../../../src/global \
 
 CONFIG += console
 
-QT += multimedia multimediawidgets widgets
+QT += multimedia multimediawidgets widgets multimedia-private
 
 SOURCES += \
     audio.cpp \

doc/src/videooverview.qdoc

@@ -90,6 +90,20 @@ You can use the \l QMediaRecorder class in conjunction with other
 classes to record video to disk.  Primarily this is used with
 the camera, so consult the \l {Camera Overview} for more information.
 
+\section2 Monitoring video frames
+You can use the \l QVideoProbe class to access video frames as they
+flow through different parts of a media pipeline when using other
+classes like \l QMediaPlayer, \l QMediaRecorder or \l QCamera.  After
+creating the high level media class, you can set the source of the
+video probe to that instance.  This can be useful for performing
+some video processing tasks (like barcode recognition, or object
+detection) while the video is rendered normally.  You can not affect
+the video frames using this class, and they may arrive at a slightly
+different time than they are being rendered.
+
+Here's an example of installing a video probe while recording the camera:
+    \snippet doc/src/snippets/multimedia-snippets/media.cpp Video probe
+
 \section1 Examples
 
 There are both C++ and QML examples available.