如何将GStreamer捕获的图像直接存入PyQt5变量？

我现有一条GStreamer管道，可捕获图像并保存至指定文件夹，命令如下：

gst-launch-1.0 nvarguscamerasrc num-buffers=1 sensor_id=0 ! 'video/x-raw(memory:NVMM), width=4608, height=2592, framerate=14/1, format=NV12' ! nvjpegenc ! filesink location=myImage.jpg

我希望跳过GStreamer存文件的步骤，直接将捕获的图像存入Python变量，以便在PyQt5中用于显示。以下是我计划使用该图像的PyQt5精简代码：

from PyQt5.QtWidgets import QLabel, QMainWindow, QApplication, QWidget, QVBoxLayout
from PyQt5.QtGui import QPixmap
import sys

#Something along the lines of 
#imageData = getImageFromGstreamer("gst-launch-1.0....")

class Menu(QMainWindow):

    def __init__(self):
        super().__init__()
        self.setWindowTitle("Title")
        
        self.central_widget = QWidget()               
        self.setCentralWidget(self.central_widget)    
        lay = QVBoxLayout(self.central_widget)
        
        label = QLabel(self)
        pixmap = QPixmap('logo.png') # QPixmap(imageData)
        label.setPixmap(pixmap)
        self.resize(pixmap.width(), pixmap.height())
        
        lay.addWidget(label)
        self.show()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = Menu()
    sys.exit(app.exec_())

请问PyQt5是否有可直接获取GStreamer输出图像的相关库？

PyQt5本身没有直接对接GStreamer的库，但可以通过GStreamer的Python绑定（gst-python）或者PyGObject实现，直接从GStreamer管道获取图像数据，再转换成PyQt5可识别的格式。

具体实现代码 #

from PyQt5.QtWidgets import QLabel, QMainWindow, QApplication, QWidget, QVBoxLayout
from PyQt5.QtGui import QPixmap, QImage
import sys
import gi
gi.require_version('Gst', '1.0')
from gi.repository import Gst, GObject

# 初始化GStreamer
Gst.init(None)
GObject.threads_init()

def get_image_from_gstreamer():
    # 重构GStreamer管道，用appsink替代文件输出
    pipeline_str = (
        "nvarguscamerasrc num-buffers=1 sensor_id=0 ! "
        "video/x-raw(memory:NVMM), width=4608, height=2592, framerate=14/1, format=NV12 ! "
        "nvvidconv ! video/x-raw, format=BGRx ! "
        "videoconvert ! video/x-raw, format=BGR ! "
        "appsink emit-signals=True sync=False"
    )
    pipeline = Gst.parse_launch(pipeline_str)
    appsink = pipeline.get_by_name("appsink0")

    image_data = None

    # 处理appsink的新样本信号
    def on_new_sample(sink):
        nonlocal image_data
        sample = sink.emit("pull-sample")
        buf = sample.get_buffer()
        caps = sample.get_caps()
        
        # 获取图像尺寸
        width = caps.get_structure(0).get_value("width")
        height = caps.get_structure(0).get_value("height")
        
        # 读取缓冲区数据并转换为QImage
        success, map_info = buf.map(Gst.MapFlags.READ)
        if success:
            image = QImage(map_info.data, width, height, QImage.Format_BGR888)
            image_data = image.copy()
            buf.unmap(map_info)
        return False

    appsink.connect("new-sample", on_new_sample)

    # 启动管道并等待处理完成
    pipeline.set_state(Gst.State.PLAYING)
    bus = pipeline.get_bus()
    bus.timed_pop_filtered(Gst.CLOCK_TIME_NONE, Gst.MessageType.EOS | Gst.MessageType.ERROR)
    pipeline.set_state(Gst.State.NULL)

    return image_data

class Menu(QMainWindow):

    def __init__(self):
        super().__init__()
        self.setWindowTitle("GStreamer Image Capture")
        
        self.central_widget = QWidget()               
        self.setCentralWidget(self.central_widget)    
        lay = QVBoxLayout(self.central_widget)
        
        label = QLabel(self)
        # 获取图像并转换为QPixmap显示
        qimage = get_image_from_gstreamer()
        if qimage:
            pixmap = QPixmap.fromImage(qimage)
            label.setPixmap(pixmap)
            self.resize(pixmap.width(), pixmap.height())
        
        lay.addWidget(label)
        self.show()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = Menu()
    sys.exit(app.exec_())

关键说明 #

• 替换原管道的nvjpegenc ! filesink为nvvidconv ! videoconvert ! appsink，通过appsink直接获取原始图像数据
• 将图像格式转换为BGR，适配QImage的Format_BGR888格式，方便一键转为QPixmap用于PyQt5显示
• 利用GStreamer的信号机制，在捕获到图像样本时立即处理并停止管道，避免资源占用

内容的提问来源于stack exchange，提问作者DrakeJest