The delay difference of live video stream between gst-launch-1.0 command and appsink callback
θιθΏ
912850408 at qq.com
Thu May 4 08:46:45 UTC 2017
I have encountered a confusing problem on my jetson-TX1(gstreamer1.8,qt5.5,opencv3.2 which has been configured with gstreamer).
First,I tested "gst-launch-1.0 rtspsrc location=rtsp://admin:admin12345@192.168.1.64:554/h264/ch33/main/av_stream latency=0 ! decodebin ! videoconvert ! xvimagesink sync=false" in command window and I got real-time video of my IP camera.
However,when I want to use gstreamer in qt project to do opencv displaying.I tested the follow code which used appsink callback and the result is that video is not real-time and the delaying is accumulating over time.The result is unacceptable in my real-time project.Could someone help me?Best wishes to you all!
#include <gst/gst.h>
#include <gst/app/gstappsink.h>
#include <stdlib.h>
#include<QTime>
#include<QDebug>
#include "opencv2/opencv.hpp"
using namespace cv;
#define CAPS "video/x-raw,format=BGR,fFrameRate=25/1,width=1280,height=720"
// TODO: use synchronized deque
GMainLoop *loop;
std::deque<Mat> frameQueue;
int live_flag = 0;
int quit_flag = 0;
int sum_time=0;
GstFlowReturn new_preroll(GstAppSink *appsink, gpointer data)
{
g_print ("Got preroll!\n");
return GST_FLOW_OK;
}
GstFlowReturn new_sample(GstAppSink *appsink, gpointer data)
{
QTime time;
time.start();
static int framecount = 0;
framecount++;
static int width=0, height=0 ;
GstSample *sample = gst_app_sink_pull_sample(appsink);
GstCaps *caps = gst_sample_get_caps(sample);
GstBuffer *buffer = gst_sample_get_buffer(sample);
static GstStructure *s;
const GstStructure *info = gst_sample_get_info(sample);
// ---- get width and height
if(framecount==1)
{
if(!caps)
{
g_print("Could not get image info from filter caps");
exit(-11);
}
s = gst_caps_get_structure(caps,0);
gboolean res = gst_structure_get_int(s, "width", &width);
res |= gst_structure_get_int(s, "height", &height);
if(!res)
{
g_print("Could not get image width and height from filter caps");
exit(-12);
}
g_print("Image size: %d\t%d\n",width,height);
}
// ---- Read frame and convert to opencv format ---------------
GstMapInfo map;
gst_buffer_map (buffer, &map, GST_MAP_READ);
// convert gstreamer data to OpenCV Mat, you could actually
// resolve height / width from caps...
Mat frame(Size(width, height), CV_8UC3, (char*)map.data, Mat::AUTO_STEP);
// this lags pretty badly even when grabbing frames from webcam
//Mat edges;
//cvtColor(frame, edges, CV_RGB2GRAY);
//GaussianBlur(edges, edges, Size(7,7), 1.5, 1.5);
//Canny(edges, edges, 0, 30, 3);
imshow("stream", frame);
//char key = cv::waitKey(10);
//if(key!=-1) quit_flag = 1;
gst_buffer_unmap(buffer, &map);
// ------------------------------------------------------------
// print dot every 30 frames
if (framecount%30 == 0) {
g_print (".");
}
// show caps on first frame
if (framecount == 1) {
g_print ("%s\n", gst_caps_to_string(caps));
}
gst_sample_unref (sample);
sum_time =time.elapsed();
qDebug()<<"time:"<<sum_time<<"\n";
return GST_FLOW_OK;
}
static gboolean my_bus_callback (GstBus *bus, GstMessage *message, gpointer data)
{
g_print ("Got %s message from %s\n", GST_MESSAGE_TYPE_NAME (message), GST_OBJECT_NAME (message->src));
switch (GST_MESSAGE_TYPE (message))
{
case GST_MESSAGE_ERROR:
{
GError *err;
gchar *debug;
gst_message_parse_error (message, &err, &debug);
g_print ("Error from %s: %s\n", GST_OBJECT_NAME (message->src), err->message);
g_error_free (err);
g_free (debug);
break;
}
case GST_MESSAGE_EOS:
/* end-of-stream */
quit_flag = 1;
break;
case GST_MESSAGE_STATE_CHANGED:
GstState oldstate, newstate;
gst_message_parse_state_changed(message, &oldstate, &newstate, NULL);
g_print ("Element %s changed state from %s to %s.\n",
GST_OBJECT_NAME (message->src),
gst_element_state_get_name (oldstate),
gst_element_state_get_name (newstate));
break;
default:
/* unhandled message */
break;
}
/* we want to be notified again the next time there is a message
* on the bus, so returning TRUE (FALSE means we want to stop watching
* for messages on the bus and our callback should not be called again)
*/
return TRUE;
}
int main (int argc, char *argv[])
{
GError *error = NULL;
GstElement *pipeline, *sink;
GstStateChangeReturn state_ret;
GstSample *sample;
gst_init (&argc, &argv);
gchar *descr = g_strdup(
"rtspsrc location=rtsp://admin:admin12345@192.168.1.64:554/h264/ch33/main/av_stream latency=0 ! "
"decodebin ! "
"videoconvert ! "
"appsink name=sink sync=false"
);
// gchar *descr = g_strdup(
// "rtspsrc location=\"rtsp://admin:admin12345@192.168.1.64:554/h264/ch33/main/av_stream\" latency=0 ! "
// "decodebin ! "
// "videoconvert ! "
// "xvimagesink name=sink sync=true"
// );
pipeline = gst_parse_launch (descr, &error);
if (error != NULL)
{
g_print ("could not construct pipeline: %s\n", error->message);
g_error_free (error);
exit (-1);
}
/* get sink */
sink = gst_bin_get_by_name (GST_BIN (pipeline), "sink");
/*set to pause*/
state_ret = gst_element_set_state(pipeline, GST_STATE_PAUSED);
switch(state_ret)
{
case GST_STATE_CHANGE_FAILURE:
g_print ("failed to play the file\n");
exit (-2);
case GST_STATE_CHANGE_NO_PREROLL:
/* for live sources, we need to set the pipeline to PLAYING before we can
* receive a buffer. */
g_print ("live source detected\n");
live_flag = 1;
break;
default:
break;
}
gst_app_sink_set_emit_signals((GstAppSink*)sink, true);
gst_app_sink_set_drop((GstAppSink*)sink, true);
gst_app_sink_set_max_buffers((GstAppSink*)sink, 1);
GstAppSinkCallbacks callbacks = { NULL, new_preroll, new_sample };
gst_app_sink_set_callbacks (GST_APP_SINK(sink), &callbacks, NULL, NULL);
GstBus *bus;
guint bus_watch_id;
bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
bus_watch_id = gst_bus_add_watch (bus, my_bus_callback, NULL);
gst_object_unref (bus);
gst_element_set_state (GST_ELEMENT (pipeline), GST_STATE_PLAYING);
namedWindow("stream",1);
loop = g_main_loop_new(NULL,false);
g_main_loop_run(loop);
cv::destroyWindow("stream");
g_print ("Going to end of main!\n");
gst_element_set_state (GST_ELEMENT (pipeline), GST_STATE_NULL);
gst_object_unref (GST_OBJECT (pipeline));
return 0;
}
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