1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
|
/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** 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.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
/*!
\example demos/spectrum
\title Spectrum Analyzer
The Spectrum Analyzer demo shows how the \l{QtMultimedia Module} can be
used in Qt applications to capture and then play back an audio stream.
\image spectrum-demo.png
Because QtMultimedia allows the application to access the raw audio
stream, the data can either be inspected or modified by the application.
The Spectrum Analyzer demo displays three pieces of information while
audio is being either captured or played back:
\list
\o Information about the raw audio stream, shown in the uppermost widget:
\list
\o The amount of data currently in the buffer, shown in blue
\o The segment of data which was most recently analysed to compute
the frequency spectrum, shown in green
\o The raw audio waveform, shown in white and scrolling from right to
left
\endlist
\o A representation of the frequency spectrum, shown at the lower left
\o The current RMS level of the audio stream, and the recent 'high
watermark' level, shown at the lower right
\endlist
Spectrum analysis is performed by calculating the Fast Fourier Transform
(FFT) of a segment of audio data. An open-source library,
\l{http://ldesoras.free.fr/prod.html}{FFTReal}, against which the
application is dynamically linked, is used to compute the transform.
*/
|
