example: add audiopipeline to show how to write an audio player

examples/audiopipeline/audiopipeline.pro

@@ -0,0 +1,5 @@
+PROJECTROOT = $$PWD/../..
+include($$PROJECTROOT/src/libQtAV.pri)
+preparePaths($$OUT_PWD/../../out)
+
+include(src.pri)

examples/audiopipeline/main.cpp

@@ -0,0 +1,97 @@
+/******************************************************************************
+    audiopipeline:  this file is part of QtAV examples
+    Copyright (C) 2015 Wang Bin <[email protected]>
+
+*   This file is part of QtAV
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 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 General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+******************************************************************************/
+
+#include <QtAV>
+#include <QtCore/QCoreApplication>
+#include <QtCore/QScopedPointer>
+#include <QtDebug>
+using namespace QtAV;
+static const int kBufferSize = 1024;
+
+int main(int argc, char *argv[])
+{
+    QCoreApplication a(argc, argv);
+    qDebug() << "usage: " << a.applicationFilePath().split("/").last().append(" url");
+    if (a.arguments().size() < 2)
+        return 0;
+    QScopedPointer<AudioOutput> ao(new AudioOutput());
+    AVDemuxer demuxer;
+    demuxer.setMedia(a.arguments().last());
+    if (!demuxer.load()) {
+        qWarning() << "Failed to load file " << demuxer.fileName();
+        return 1;
+    }
+    QScopedPointer<AudioDecoder> dec(AudioDecoder::create()); // delete by user
+    dec->setCodecContext(demuxer.audioCodecContext());
+    //dec->prepare();
+    if (!dec->open())
+        qFatal("open decoder error");
+    int astream = demuxer.audioStream();
+    Packet pkt;
+    while (!demuxer.atEnd()) {
+        if (!pkt.isValid()) { // continue to decode previous undecoded data
+            if (!demuxer.readFrame() || demuxer.stream() != astream)
+                continue;
+            pkt = demuxer.packet();
+        }
+        if (!dec->decode(pkt)) {
+            pkt = Packet(); // set invalid to read from demuxer
+            continue;
+        }
+        // decode the rest data in the next loop. read from demuxer if no data remains
+        pkt.data = QByteArray::fromRawData(pkt.data.constData() + pkt.data.size() - dec->undecodedSize(), dec->undecodedSize());
+        AudioFrame frame(dec->frame()); // why is faster to call frame() for hwdec? no frame() is very slow for VDA
+        if (!frame)
+            continue;
+        //frame.setAudioResampler(dec->resampler()); // if not set, always create a resampler in AudioFrame.to()
+        AudioFormat af(frame.format());
+        if (!ao->isOpen()) {
+            dec->resampler()->setOutAudioFormat(af);
+            // if decoded format is not supported by audio renderer, change decoder output format
+            if (!ao->isSupported(af)) {
+                af.setSampleFormat(ao->preferredSampleFormat());
+                af.setChannelLayout(ao->preferredChannelLayout());
+                dec->resampler()->setOutAudioFormat(af);
+                dec->prepare();
+            }
+            // now af is supported by audio renderer. it's safe to open
+            ao->setAudioFormat(af);
+            ao->setBufferSize(kBufferSize);
+            if (!ao->open())
+                qFatal("Open audio output error");
+#if 0 // always resample ONCE due to QtAV bug
+            // the first format unsupported frame still need to be converted to a supported format
+            if (!ao->isSupported(frame.format()))
+                frame = frame.to(af);
+#endif
+        }
+        printf("playing: %.3f... data size: %d\r", frame.timestamp(), frame.data().size());
+        fflush(0);
+        // always resample ONCE. otherwise data are all 0x0. QtAV bug
+        frame = frame.to(af);
+        QByteArray data(frame.data());
+        while (!data.isEmpty()) {
+            ao->play(QByteArray::fromRawData(data.constData(), qMin(data.size(), kBufferSize)));
+            data.remove(0, qMin(data.size(), kBufferSize));
+        }
+    }
+    // dec, ao will be closed in dtor. demuxer will call unload in dtor
+    return 0;
+}

examples/audiopipeline/src.pri

@@ -0,0 +1,3 @@
+TEMPLATE = app
+CONFIG -= app_bundle
+SOURCES += main.cpp

examples/examples.pro

@@ -1,9 +1,10 @@
 TEMPLATE = subdirs
 
 SUBDIRS = common
-
-!no-widgets:!android {
-SUBDIRS += \
+!android {
+  SUBDIRS += audiopipeline
+!no-widgets {
+  SUBDIRS += \
     sharedoutput \
     simpletranscode \
     simpleplayer \
@@ -13,8 +14,10 @@ SUBDIRS += \
     videographicsitem \
     videogroup \
     videowall
+
+  player.depends += common
+}
 }
-player.depends += common
 
 greaterThan(QT_MAJOR_VERSION, 4) {
   greaterThan(QT_MINOR_VERSION, 3) {