我正在尝试使用QtGStreamer来流式传输相机帧并将其渲染到QML窗口上。我有一个简单的Gstreamer管道，当我使用 <body ng-app='myApp'>
<form id='form' ng-controller='logIn'>
<h1>Log In</h1>
<input type="text" id="username" placeholder="Enter Username" />
<input type="password" id="password"placeholder="Enter Password" />
<button id="button" type="button" ng-click='log()'>Click This</button>
</form>
<form id='form2' ng-controller='registerUser'>
<h1>Register</h1>
<input type='text' id='registerName' placeholder='Enter Username'/>
<input type='password' id='registerPass' placeholder='Enter Password'/>
<button id='registerButton' type='button' ng-click='place()'>Register</button>
</form>
gst-launch-1.0现在我创建一个相应的QtGStreamer管道：
gst-launch-1.0 autovideosrc ! videoscale ! video/x-raw, width=480,height=270 ! xvimagesink -e
首先，这真的很慢。虽然原始gstreamer命令可以30帧/秒的速度轻松运行，但每秒运行几帧。当我设置void Streamer::startStreaming()
{
if (!m_streaming_pipeline) {
m_streaming_pipeline = QGst::Pipeline::create();
if (m_streaming_pipeline) {
QGst::ElementPtr source = QGst::ElementFactory::make("autovideosrc");
QGst::ElementPtr scale = QGst::ElementFactory::make("videoscale");
scale->setProperty("caps", QGst::Caps::fromString("video/x-raw, width=480,height=270"));
if (m_videoSink) {
m_videoSink->setProperty("sync", false);
m_streaming_pipeline->add(source, scale, m_videoSink);
source->link(scale);
scale->link(m_videoSink);
QGst::BusPtr bus = m_streaming_pipeline->bus();
bus->addSignalWatch();
QGlib::connect(bus, "message", this, &Recorder::onBusMessage);
m_streaming_pipeline->setState(QGst::StatePlaying);
qDebug() << "Done";
}
}
}
}
GST_DEBUG=3我注意到的另一件事是，渲染的帧，几乎是翻转颜色方案。因此，似乎沿线的某些东西也在翻转颜色通道。
修改
我发现我需要添加一个capsfilter才能获得正确的格式。所以添加如下内容：
0:00:08.661824920 23980 0x2ac6370 WARN v4l2bufferpool gstv4l2bufferpool.c:540:gst_v4l2_buffer_pool_set_config:<autovideosrc0-actual-src-v4l:pool:src> libv4l2 converter detected, disabling CREATE_BUFS
0:00:08.665945185 23980 0x2ac6370 WARN v4l2bufferpool gstv4l2bufferpool.c:748:gst_v4l2_buffer_pool_start:<autovideosrc0-actual-src-v4l:pool:src> Uncertain or not enough buffers, enabling copy threshold
然后通过
添加QGst::ElementPtr capsfilter = QGst::ElementFactory::make("capsfilter", "capsfilter");
capsfilter->setProperty("caps", QGst::Caps::fromString("video/x-raw, width=1920, height=1080, format=RGB, framerate=30/1"));
随后链接它解决了问题。
虽然现在我的问题是gstreamer如何在我原来的管道中选择一个有效的格式？