Question

我有一个使用gstreamer的小型qt / c ++程序。它可以在debian 64bit上正常工作，而在运行raspbian的Raspberry Pi 3上则无法工作。

程序将在/ dev / video0显示USB网络摄像头，并将其流式传输到指定的IP地址。（为了进行测试，我使用环回地址，并且在同一台计算机上有一个RTP接收器程序来显示流）

我在两台计算机上都安装了qt creator，并且程序在目标计算机上构建。（无交叉编译）

在树莓派上运行时，“ GstStateChangeReturn”返回为“ GST_STATE_CHANGE_FAILURE”

这是完整的代码：

gstreamer_stream_and_display_test.pro

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <glib.h>
#include <gst/gst.h>
#include <gst/video/videooverlay.h>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
    GstElement *pipeline0;
    GstStateChangeReturn sret0;
};

#endif // MAINWINDOW_H

mainwindow.h

#include "mainwindow.h"
#include <QApplication>
#include <glib.h>
#include <gst/gst.h>
#include <gst/video/videooverlay.h>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    gst_init (&argc, &argv);
    MainWindow w;
    w.show();

    return a.exec();
}

main.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QApplication>
#include <QWidget>
#include <QDebug>
#include <glib.h>
#include <gst/gst.h>
#include <gst/video/videooverlay.h>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    setFixedSize(1280,720);
    setWindowTitle("Stream and Display Test");

    WId xwinid = winId();
    pipeline0 = gst_pipeline_new("myPipeline");
    GstElement *v4l2src = gst_element_factory_make("v4l2src", "v4l2src");
    GstElement *capsfilter = gst_element_factory_make("capsfilter", "capsfilter");
    GstElement *tee = gst_element_factory_make("tee", "tee");
    GstElement *encoder = gst_element_factory_make("jpegenc", "encoder");
    GstElement *videoConverter = gst_element_factory_make("videoconvert", "videoConverter");
    GstElement *rtp = gst_element_factory_make("rtpjpegpay", "rtp");
    GstElement *queueDisplay = gst_element_factory_make("queue", "queueDisplay");
    GstElement *queueStreamer = gst_element_factory_make("queue", "queueStreamer");
    GstElement *udpsink = gst_element_factory_make("udpsink", "udpsink");
    GstElement *videoSink = gst_element_factory_make("xvimagesink", "videoSink");

    //                               jpegenc -> rtpjpegpay -> udpsink
    //v4l2src -> capsfilter -> tee <
    //                               videoconvert -> queue -> xvimagesink

    g_object_set(udpsink, "port", 5200, NULL);
    g_object_set(udpsink, "host", "127.0.0.1", NULL);
    GstCaps *caps = gst_caps_from_string("video/x-raw, width=(int)1280, height=(int)720");
    g_object_set(capsfilter, "caps", caps, NULL);

    //add elements to bin
    gst_bin_add_many(GST_BIN(pipeline0), v4l2src, capsfilter, tee, encoder, queueDisplay, queueStreamer, videoConverter, rtp, udpsink, videoSink, NULL);

    //Link source elements
    if(!gst_element_link_many(v4l2src, capsfilter, tee, NULL))
    {
        qDebug()<<"Unable to link source elements";
    }
    //Link streaming elements
    if(!gst_element_link_many(queueStreamer, encoder, rtp, udpsink, NULL))
    {
        qDebug()<<"Unable to link streaming elements";
    }
    //Link display elements
    if(!gst_element_link_many(queueDisplay, videoConverter, videoSink, NULL))
    {
        qDebug()<<"Unable to link display elements";
    }

    //Create Tee Pads
    GstPad *teeStreamerPad = gst_element_get_request_pad(tee, "src_%u");
    GstPad *queueStreamerPad = gst_element_get_static_pad(queueStreamer, "sink");
    GstPad *teeDisplayPad = gst_element_get_request_pad(tee, "src_%u");
    GstPad *queueDisplayPad= gst_element_get_static_pad(queueDisplay, "sink");

    //Link Tee and Queue Pads
    if(gst_pad_link(teeStreamerPad, queueStreamerPad) != GST_PAD_LINK_OK)
    {
        qDebug()<<"Unable to link streamer pads";
    }
    if(gst_pad_link(teeDisplayPad, queueDisplayPad) != GST_PAD_LINK_OK)
    {
        qDebug()<<"Unable to link display pads";
    }

    gst_object_unref(queueStreamerPad);
    gst_object_unref(queueDisplayPad);

    //Setup Gui Display Area
    gint viewX = 0;
    gint viewY = 0;
    gint camResX = 1280;
    gint camResY = 720;
    gst_video_overlay_set_window_handle(GST_VIDEO_OVERLAY (videoSink), xwinid);
    gst_video_overlay_set_render_rectangle(GST_VIDEO_OVERLAY (videoSink), viewX, viewY, camResX, camResY);

    //start pipeline
    sret0 = gst_element_set_state(pipeline0, GST_STATE_PLAYING);
    if(sret0 == GST_STATE_CHANGE_FAILURE)
    {
        qDebug()<<"Error: GST_STATE_CHANGE_FAILURE";
        close();
    }
    else
    {
        qDebug()<<sret0;
    }
}

MainWindow::~MainWindow()
{
    gst_element_set_state (pipeline0, GST_STATE_NULL);
    gst_object_unref(pipeline0);
    delete ui;
    qDebug()<<"Closed correctly";
}

mainwindow.cpp

compile 'com.squareup.retrofit2:retrofit:2.3.0'
compile 'com.squareup.retrofit2:converter-gson:2.3.0'
compile 'com.squareup.retrofit2:converter-scalars:2.3.0'

Answer 1

我认为您直接使用gstreamer使整个过程复杂化了。

使用多媒体模块中的Qt QCamera类应该更容易：它允许您播放网络摄像头流（还：您可以记录，捕获帧，获取网络摄像头信息等）。

您甚至可以编写自己的QAbstractVideoSurface来在线播放视频。

This example无疑是一个良好的开端。

在Debian上工作的Qt / gstreamer代码在rasbian上不起作用

1 个答案: