树莓派GStreamer管道问题：无法调用摄像头

我正在实现图像跟踪功能，把教程里读取.mp4文件的代码改成读取摄像头（索引0）后，程序无法正常运行。即使是运行最基础的OpenCV摄像头初始化代码，也会抛出GStreamer相关警告，无法获取实时画面。摄像头硬件本身正常，系统已识别，且安装了picamera2库。

基础测试代码 #

import cv2
cap = cv2.VideoCapture(0)

报错信息 #

[ WARN:0@0.196] global ./modules/videoio/src/cap_gstreamer.cpp (2401) handleMessage OpenCV | GStreamer warning: Embedded video playback halted; module v4l2src0 reported: Failed to allocate required memory.
[ WARN:0@0.196] global ./modules/videoio/src/cap_gstreamer.cpp (1356) open OpenCV | GStreamer warning: unable to start pipeline
[ WARN:0@0.196] global ./modules/videoio/src/cap_gstreamer.cpp (862) isPipelinePlaying OpenCV | GStreamer warning: GStreamer: pipeline have not been created

环境信息 #

• OpenCV版本：4.6.0（已启用GStreamer 1.22.0的VideoI/O组件）
• 已安装picamera2库
• 摄像头设备正常识别

目标跟踪完整代码 #

import cv2
from tracker import *

# 创建跟踪器对象
tracker = EuclideanDistTracker()

cap = cv2.VideoCapture(0)

# 固定摄像头的目标检测
object_detector = cv2.createBackgroundSubtractorMOG2(history=100, varThreshold=40)

while True:
    ret, frame = cap.read()
    height, width, _ = frame.shape

    # 提取感兴趣区域
    roi = frame[340: 720,500: 800]

    # 1. 目标检测
    mask = object_detector.apply(roi)
    _, mask = cv2.threshold(mask, 254, 255, cv2.THRESH_BINARY)
    contours, _ = cv2.findContours(mask, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
    detections = []
    for cnt in contours:
        # 计算面积，过滤小目标
        area = cv2.contourArea(cnt)
        if area > 100:
            x, y, w, h = cv2.boundingRect(cnt)
            detections.append([x, y, w, h])

    # 2. 目标跟踪
    boxes_ids = tracker.update(detections)
    for box_id in boxes_ids:
        x, y, w, h, id = box_id
        cv2.putText(roi, str(id), (x, y - 15), cv2.FONT_HERSHEY_PLAIN, 2, (255, 0, 0), 2)
        cv2.rectangle(roi, (x, y), (x + w, y + h), (0, 255, 0), 3)

    cv2.imshow("roi", roi)
    cv2.imshow("Frame", frame)
    cv2.imshow("Mask", mask)

    key = cv2.waitKey(30)
    if key == 27:
        break

cap.release()
cv2.destroyAllWindows()

疑问 #

我编程经验不多，看到其他人直接用cv2.VideoCapture(0)就能成功读取摄像头画面，但我这里不行。想知道问题出在哪？该怎么配置GStreamer管道让项目正常运行？

内容的提问来源于stack exchange，提问作者user24088758