I have the following working pipeline. It has been tested using both command-line tool gst-launch-1.0 and function gst_parse_launch(), and works in both cases.
videotestsrc ! video/x-raw,width=640,height=480 ! videocrop left=80 right=80 ! tee name=t ! queue ! glupload ! glimagesink t. ! queue ! jpegenc ! avimux ! filesink location=output.avi
I've tried to set it up manually in code, but I'm now stuck on the following error (the application opens, but no video is displayed):
Error received from element videotestsrc0 : Internal data flow error.
Debugging information: gstbasesrc.c(2948): gst_base_src_loop (): /GstPipeline:pipeline0/GstVideoTestSrc:videotestsrc0: streaming task paused, reason not-negotiated (-4)
I'm using GStreamer in a Qt application and the glimagesink links the video to a QML type. All code related to GStreamer is located in a GStreamer class called GStreamer. The entire cpp file is posted below, in case the issue is located somewhere I wouldn't guess. I apologize for non-relevant code.
static gboolean busCallback(GstBus *bus, GstMessage *message, gpointer data);
GStreamer::GStreamer(QQuickItem *parent) : QQuickItem(parent)
{
qDebug() << "Constructed GSteamer";
}
void GStreamer::createPipeline()
{
qDebug() << "Creating pipeline";
if(m_source.isEmpty()){
qDebug() << "Error: Missing source property for GStreamer component";
return;
}
if(m_videoItem.isEmpty()){
qDebug() << "Error: Missing videoItem property for GStreamer component";
return;
}
m_pipeline = gst_pipeline_new(NULL);
m_sink = NULL;
QByteArray ba = m_source.toLatin1();
m_src = gst_element_factory_make(ba.data(), NULL);
g_assert(m_src);
m_filter = gst_element_factory_make("capsfilter", "filter");
g_assert(m_filter);
g_object_set(G_OBJECT (m_filter), "caps", gst_caps_new_simple("video/x-raw",
"width", G_TYPE_INT, 640,
"height", G_TYPE_INT, 480,
NULL),
NULL);
m_convert = gst_element_factory_make("videoconvert", NULL);
g_assert(m_convert);
m_crop = gst_element_factory_make("videocrop", "crop");
g_assert(m_crop);
g_object_set(G_OBJECT (m_crop), "left", 80, "right", 80, NULL);
// Tee
m_tee = gst_element_factory_make("tee", "videotee");
g_assert(m_tee);
// Display queue
m_displayQueue = gst_element_factory_make("queue", "displayQueue");
g_assert(m_displayQueue);
m_upload = gst_element_factory_make("glupload", NULL);
g_assert(m_upload);
m_sink = gst_element_factory_make("qmlglsink", NULL);
g_assert(m_sink);
// Record queue
m_recordQueue = gst_element_factory_make("queue", "recordQueue");
g_assert(m_recordQueue);
m_encode = gst_element_factory_make("jpegenc", NULL);
g_assert(m_encode);
m_mux = gst_element_factory_make("avimux", NULL);
g_assert(m_mux);
m_filesink = gst_element_factory_make("filesink", NULL);
g_assert(m_filesink);
g_object_set(G_OBJECT(m_filesink), "location", "output.avi", NULL);
gst_bin_add_many(GST_BIN (m_pipeline), m_src, m_filter, m_convert, m_crop, m_upload, m_sink, NULL);
gst_bin_add_many(GST_BIN(m_pipeline), m_tee, m_displayQueue, m_recordQueue, m_encode, m_mux, m_filesink, NULL);
// If I only link this simple pipeline, it works fine
/*
if(!gst_element_link_many(m_src, m_filter, m_convert, m_crop, m_upload, m_sink, NULL)){
qDebug() << "Unable to link source";
}
*/
if(!gst_element_link_many(m_src, m_filter, m_convert, m_crop, m_tee, NULL)){
qDebug() << "Unable to link source";
}
if(!gst_element_link_many(m_displayQueue, m_upload, m_sink, NULL)){
qDebug() << "Unable to link display queue";
}
if(!gst_element_link_many(m_recordQueue, m_encode, m_mux, m_filesink, NULL)){
qDebug() << "Unable to link record queue";
}
GstPad *teeDisplayPad = gst_element_get_request_pad(m_tee, "src_%u");
GstPad *queueDisplayPad = gst_element_get_static_pad(m_displayQueue, "sink");
GstPad *teeRecordPad = gst_element_get_request_pad(m_tee, "src_%u");
GstPad *queueRecordPad = gst_element_get_static_pad(m_recordQueue, "sink");
if(gst_pad_link(teeDisplayPad, queueDisplayPad) != GST_PAD_LINK_OK){
qDebug() << "Unable to link display tee";
}
if(gst_pad_link(teeRecordPad, queueRecordPad) != GST_PAD_LINK_OK){
qDebug() << "Unable to link record tee";
}
//gst_object_unref(teeDisplayPad);
gst_object_unref(queueDisplayPad);
//gst_object_unref(teeRecordPad);
gst_object_unref(queueRecordPad);
QQuickItem *videoItem = window()->findChild<QQuickItem *> (m_videoItem);
g_object_set(m_sink, "widget", videoItem, NULL);
// This will call gst_element_set_state(m_pipeline, GST_STATE_PLAYING) when the window is ready
window()->scheduleRenderJob (new SetPlaying (m_pipeline), QQuickWindow::BeforeSynchronizingStage);
m_bus = gst_element_get_bus(m_pipeline);
gst_bus_add_watch(m_bus, busCallback, m_loop);
gst_object_unref(m_bus);
m_loop = g_main_loop_new(NULL, false);
g_main_loop_run(m_loop);
}
static gboolean busCallback(GstBus *bus, GstMessage *message, gpointer data){
qDebug() << "Callback function reached";
switch(GST_MESSAGE_TYPE(message)){
case GST_MESSAGE_ERROR:
GError *error;
gchar *debugInfo;
gst_message_parse_error(message, &error, &debugInfo);
qDebug() << "Error received from element" << GST_OBJECT_NAME(message->src) << ":" << error->message;
qDebug() << "Debugging information:" << (debugInfo ? debugInfo : "none");
//g_printerr ("Error received from element %s: %s\n", GST_OBJECT_NAME (m_message->src), error->message);
//g_printerr ("Debugging information: %s\n", debugInfo ? debugInfo : "none");
g_clear_error (&error);
g_free (debugInfo);
g_main_loop_quit(static_cast<GMainLoop *>(data));
break;
case GST_MESSAGE_EOS:
qDebug() << "End-Of-Stream reached.";
g_main_loop_quit(static_cast<GMainLoop *>(data));
break;
default:
qDebug() << "Unexpected message received.";
break;
}
return true;
}
/**
The rest of the code is probably not relevant. It contains
only destructor and some getters and setters.
**/
GStreamer::~GStreamer()
{
gst_object_unref(m_bus);
gst_element_set_state(m_pipeline, GST_STATE_NULL);
gst_object_unref(m_pipeline);
}
QString GStreamer::source() const
{
return m_source;
}
void GStreamer::setSource(const QString &source)
{
if(source != m_source){
m_source = source;
}
}
QString GStreamer::videoItem() const
{
return m_videoItem;
}
void GStreamer::setVideoItem(const QString &videoItem)
{
if(videoItem != m_videoItem){
m_videoItem = videoItem;
}
}
All member variables are defined in the .h file.
If I don't add tee element to the bin and links it in the pipeline, then the video shows up on the screen as expected. So I guess I'm messing up the pads on the tee element.
I've been following the tutorials in GStreamers documentation, so I don't understand why it's not working.
Hope someone can help.
