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
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
/*
Copyright (C) 2010 George Kiagiadakis <kiagiadakis.george@gmail.com>
This library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <iostream>
#include <signal.h>
#include <QtCore/QCoreApplication>
#include <QtCore/QFile>
#include <QtCore/QTime>
#include <QGlib/Signal>
#include <QGst/Global>
#include <QGst/Pipeline>
#include <QGst/ElementFactory>
#include <QGst/GhostPad>
#include <QGst/Structure>
#include <QGst/Bus>
#include <QGst/Message>
#include <QGst/Query>
#include <QGst/Clock>
#include <QGst/Event>
/* This is a simple example of a command-line audio player. It accepts the filename of
* an audio file as the first command line argument and then constructs a pipeline
* that uses decodebin2 to decode the audio stream and autoaudiosink to output it to
* the sound card. In the future this example will be expanded to handle video as well
* and perhaps it will gain a simple GUI too. */
class Player
{
public:
Player(const QString & fileName);
~Player();
private:
void onBusSyncMessage(const QGst::MessagePtr & message);
void onNewDecodedPad(QGst::PadPtr newPad);
static QGst::BinPtr createAudioSinkBin();
/* This smart pointer is needed to keep a reference to the underlying GstPipeline object.
* Even if we are not going to use it, we must keep a reference to the pipeline,
* so that it remains in memory, together with all its child elements. If this
* reference is gone, the pipeline and all the elements will be destroyed.
* Note that we don't need to keep references to the individual elements, because
* when they are added in the pipeline, the pipeline keeps a reference on them. */
QGst::PipelinePtr m_pipeline;
};
Player::Player(const QString & fileName)
{
m_pipeline = QGst::Pipeline::create();
QGst::ElementPtr filesrc = QGst::ElementFactory::make("filesrc");
QGst::ElementPtr decodebin = QGst::ElementFactory::make("decodebin2");
filesrc->setProperty("location", fileName);
QGlib::connect(decodebin, "new-decoded-pad", this, &Player::onNewDecodedPad);
m_pipeline->add(filesrc);
m_pipeline->add(decodebin);
filesrc->link(decodebin);
QGst::BusPtr bus = m_pipeline->bus();
bus->enableSyncMessageEmission();
QGlib::connect(bus, "sync-message", this, &Player::onBusSyncMessage);
m_pipeline->setState(QGst::StatePlaying);
}
Player::~Player()
{
m_pipeline->setState(QGst::StateNull);
/* When m_pipeline is destructed, the last reference to our pipeline will be gone,
* and with it all the elements, buses, etc will be destroyed too. As a result,
* there is no need to cleanup here. */
}
void Player::onBusSyncMessage(const QGst::MessagePtr & message)
{
/* WARNING this slot gets called in a different thread */
switch(message->type()) {
case QGst::MessageEos: //End of stream. We reached the end of the file.
case QGst::MessageError: //Some error occurred.
/* QCoreApplication::quit is safe to be called in another thread.
* It will schedule the main event loop to exit, when execution
* in the main thread has reached the event loop. */
QCoreApplication::quit();
break;
case QGst::MessageAsyncDone:
{
//File prerolled, queries the pipeline to get the file duration
QGst::DurationQueryPtr query = QGst::DurationQuery::create(QGst::FormatTime);
//This will create a temporary (cast to query).
m_pipeline->query(query);
//qDebug() << QGst::Clock::timeFromClockTime(query->duration());
/*Set the pipeline to seek to 6 seconds in the stream and play until it reaches 15 secs
* Notice that using element->seek() is probably better in most cases
*
QGst::SeekEventPtr evt = QGst::SeekEvent::create(1.0, QGst::FormatTime,
QGst::SeekFlagNone,
QGst::SeekTypeSet,
QGst::Clock::clockTimeFromTime(QTime(0,0,6)),
QGst::SeekTypeSet,
QGst::Clock::clockTimeFromTime(QTime(0,0,15))
);
m_pipeline->sendEvent(evt);*/
/* this is the simple seek version
m_pipeline->seek(QGst::FormatTime, QGst::SeekFlagNone,
QGst::Clock::clockTimeFromTime(QTime(0,0,15)) );*/
}
break;
default:
break;
}
}
/* This method will be called every time a new "src" pad is available on the decodebin2 element.
* Here we have to check what kind of data this pad transfers (usually it is either "audio/x-raw-*"
* or "video/x-raw-*") and connect an appropriate sink that can handle this type of data. */
void Player::onNewDecodedPad(QGst::PadPtr newPad)
{
QGst::CapsPtr caps = newPad->caps();
QGst::StructurePtr structure = caps->internalStructure(0);
/* The caps' first structure's name tells us what kind of data the pad transfers.
* Here we want to handle either audio/x-raw-int or audio/x-raw-float. Both types
* can be handled by the audioconvert element that is contained in the audioSinkBin,
* so there is no need to handle them separately */
if (structure->name().contains("audio/x-raw")) {
QGst::BinPtr audioSinkBin = createAudioSinkBin();
m_pipeline->add(audioSinkBin);
/* The newly created bin must go to the playing state in order to function.
* Here we tell it to synchronise its state with its parent, the pipeline,
* which is scheduled to go to the playing state. */
audioSinkBin->syncStateWithParent();
newPad->link(audioSinkBin->getStaticPad("sink"));
}
}
QGst::BinPtr Player::createAudioSinkBin()
{
QGst::BinPtr bin = QGst::Bin::create();
QGst::ElementPtr audioconvert = QGst::ElementFactory::make("audioconvert");
QGst::ElementPtr audiosink = QGst::ElementFactory::make("autoaudiosink");
bin->add(audioconvert);
bin->add(audiosink);
audioconvert->link(audiosink);
/* Add a sink pad to the bin that proxies the sink pad of the audioconvert element */
bin->addPad(QGst::GhostPad::create(audioconvert->getStaticPad("sink"), "sink"));
return bin;
}
static void sighandler(int code)
{
Q_UNUSED(code);
QCoreApplication::quit();
}
int main(int argc, char **argv)
{
QCoreApplication app(argc, argv);
QGst::init(&argc, &argv);
QString fileName;
if (argc > 1) {
fileName = QFile::decodeName(argv[1]);
}
if (!QFile::exists(fileName)) {
std::cerr << "Usage: " << argv[0] << " fileToPlay" << std::endl;
return 1;
}
Player *p = new Player(fileName);
signal(SIGINT, sighandler);
int result = app.exec();
delete p; // we must delete all gstreamer objects before calling QGst::cleanup()
QGst::cleanup();
return result;
}
|
