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前言

最近在研究mpp，通过gstreamer实现了硬解码，但是我在想我可能需要一个播放器，我之前学过qt5所以就选择了qt5来结合gstreamer开发一个简单的播放器。今天的环境基于Windows，后续会把Linux的也补上的。

注意：基于QT5，我觉得因为全平台特性，可能QT5比MFC还是有优势，代码只需要小改就可以轻松移植。

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一、安装环境

本身不需要特殊配置就支持N卡硬解码，A卡和I卡可能要借助VAAP，我手上没有设备，暂未研究。所以显卡驱动和芯片组驱动就不说了肯定都是要装的。

1.QT5

这个不介绍了，网上找找就好了。

2.gstreamer

Windows11安装并使用Gstreamer-1.0

二、代码

代码很简单，没有特别做UI，只实现了视频硬解码、播放和音频播放功能。

1.Windows实现

代码只能跑在Windows上因为播放组件是需要区分WIndows和Linux甚至MacOS的。

Gstreamer_Player.pro

QT       += core guigreaterThan(QT_MAJOR_VERSION, 4): QT += widgetsCONFIG += c++17# You can make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0SOURCES += \main.cpp \mainwindow.cppHEADERS += \mainwindow.hFORMS += \mainwindow.ui# 添加GStreamer和Glib库
unix {PKGCONFIG += gstreamer-1.0 gstreamer-video-1.0 glib-2.0 gstvideo-1.0
}# 如果你使用的是Windows，请添加以下内容，并调整路径
win32 {INCLUDEPATH += E:/gstreamer/1.0/msvc_x86_64/include/gstreamer-1.0INCLUDEPATH += E:/gstreamer/1.0/msvc_x86_64/include/glib-2.0INCLUDEPATH += E:/gstreamer/1.0/msvc_x86_64/lib/glib-2.0/includeLIBS += -LE:/gstreamer/1.0/msvc_x86_64/lib -lgstreamer-1.0 -lgobject-2.0 -lglib-2.0 -lgstvideo-1.0
}# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>
#include <gst/gst.h>
#include <gst/video/videooverlay.h>QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow
{Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();private slots:void on_playButton_clicked();private:Ui::MainWindow *ui;GstElement *pipeline;
};#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QMessageBox>
#include <QFileDialog>//代码只有Windows系统才执行
#ifdef Q_OS_WIN
#include <windows.h>
#include <dwmapi.h>
#endifMainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);gst_init(nullptr, nullptr);pipeline = gst_pipeline_new("pipeline");GstElement *source = gst_element_factory_make("filesrc", "source");GstElement *demuxer = gst_element_factory_make("decodebin", "demuxer");GstElement *videoconvert = gst_element_factory_make("videoconvert", "videoconvert");GstElement *videosink = gst_element_factory_make("d3dvideosink", "videosink");GstElement *audioconvert = gst_element_factory_make("audioconvert", "audioconvert");GstElement *audioresample = gst_element_factory_make("audioresample", "audioresample");GstElement *audiosink = gst_element_factory_make("autoaudiosink", "audiosink");//这一句可以合并，因为都是必须创建成功的if (!pipeline || !source || !demuxer || !videoconvert || !videosink || !audioconvert || !audioresample || !audiosink) {QMessageBox::critical(this, "Error", "Failed to create GStreamer elements.");return;}gst_bin_add_many(GST_BIN(pipeline), source, demuxer, videoconvert, videosink, audioconvert, audioresample, audiosink, nullptr);gst_element_link(source, demuxer);g_signal_connect(demuxer, "pad-added", G_CALLBACK(+[](GstElement *demuxer, GstPad *new_pad, gpointer user_data) {GstElement *pipeline = GST_ELEMENT(user_data);GstPad *videoconvert_sink_pad = gst_element_get_static_pad(gst_bin_get_by_name(GST_BIN(pipeline), "videoconvert"), "sink");GstPad *audioconvert_sink_pad = gst_element_get_static_pad(gst_bin_get_by_name(GST_BIN(pipeline), "audioconvert"), "sink");GstPadLinkReturn ret;GstCaps *new_pad_caps = gst_pad_get_current_caps(new_pad);GstStructure *new_pad_struct = gst_caps_get_structure(new_pad_caps, 0);const gchar *new_pad_type = gst_structure_get_name(new_pad_struct);if (g_str_has_prefix(new_pad_type, "video/x-raw")) {ret = gst_pad_link(new_pad, videoconvert_sink_pad);} else if (g_str_has_prefix(new_pad_type, "audio/x-raw")) {ret = gst_pad_link(new_pad, audioconvert_sink_pad);} else {ret = GST_PAD_LINK_OK;}if (GST_PAD_LINK_FAILED(ret)) {g_printerr("Type is '%s' but link failed.\n", new_pad_type);} else {g_print("Link succeeded (type '%s').\n", new_pad_type);}gst_object_unref(videoconvert_sink_pad);gst_object_unref(audioconvert_sink_pad);gst_caps_unref(new_pad_caps);}), pipeline);gst_element_link_many(videoconvert, videosink, nullptr);gst_element_link_many(audioconvert, audioresample, audiosink, nullptr);GstBus *bus = gst_element_get_bus(pipeline);gst_bus_add_signal_watch(bus);g_signal_connect(bus, "message::error", G_CALLBACK(+[](GstBus *bus, GstMessage *msg, gpointer user_data) {GError *err;gchar *debug_info;gst_message_parse_error(msg, &err, &debug_info);g_printerr("Error received from element %s: %s\n", GST_OBJECT_NAME(msg->src), err->message);g_printerr("Debugging information: %s\n", debug_info ? debug_info : "none");g_clear_error(&err);g_free(debug_info);}), nullptr);gst_object_unref(bus);WId winId = ui->videoWidget->winId();gst_video_overlay_set_window_handle(GST_VIDEO_OVERLAY(videosink), winId);
}MainWindow::~MainWindow()
{gst_element_set_state(pipeline, GST_STATE_NULL);gst_object_unref(pipeline);delete ui;
}void MainWindow::on_playButton_clicked()
{QString filename = QFileDialog::getOpenFileName(this, "Open Video File", "", "Video Files (*.mp4 *.avi *.mkv)");if (filename.isEmpty())return;gst_element_set_state(pipeline, GST_STATE_READY);g_object_set(G_OBJECT(gst_bin_get_by_name(GST_BIN(pipeline), "source")), "location", filename.toStdString().c_str(), nullptr);gst_element_set_state(pipeline, GST_STATE_PLAYING);
}

main.cpp

#include "mainwindow.h"#include <QApplication>int main(int argc, char *argv[])
{QApplication a(argc, argv);MainWindow w;w.show();return a.exec();
}

mainwindow.ui

一个Widget命名为videoWidget，一个Pushbutton命名为playButton。布局参考下面的：

注意：选择MSVC 2015编译链，要不然会找不到库！

三、测试效果

除非花里胡哨的特效，一般UI在Windows上和Linux上可以复用。

实测可以正常调用N卡硬解码（需要显卡支持）。

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总结

1、不算太难，复杂的应用还需要继续琢磨。
2、Windows上还是简单，我最终的目标是在开发板上实现gstreamer+qt5+硬解码播放，开发板上没有统一的接口。