树莓派4外接罗技USB相机运行picamera代码报错求助

问题说明 #

树莓派4 Model B外接罗技USB相机，参照教程运行基于picamera库的Python代码时，出现picamera.exc.PiCameraMMALError和picamera.exc.PiCameraError报错。已通过sudo raspi-config启用相机功能，但问题仍未解决。

运行代码 #

from picamera import PiCamera
import time


print("= = = = = == = = = ")
camera = PiCamera()

camera.start_preview()
time.sleep(2)

camera.capture("test.jpg")

报错信息 #

mmal: mmal_vc_component_create: failed to create component 'vc.ril.camera' (1:ENOMEM)
mmal: mmal_component_create_core: could not create component 'vc.ril.camera' (1)
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/picamera/camera.py", line 456, in _init_camera
    self._camera = mo.MMALCamera()
  File "/usr/lib/python3/dist-packages/picamera/mmalobj.py", line 2279, in __init__
    super(MMALCamera, self).__init__()
  File "/usr/lib/python3/dist-packages/picamera/mmalobj.py", line 631, in __init__
    mmal_check(
  File "/usr/lib/python3/dist-packages/picamera/exc.py", line 184, in mmal_check
    raise PiCameraMMALError(status, prefix)
picamera.exc.PiCameraMMALError: Failed to create MMAL component b'vc.ril.camera': Out of memory

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/joy/Desktop/camera.py", line 6, in <module>
    camera = PiCamera()
  File "/usr/lib/python3/dist-packages/picamera/camera.py", line 431, in __init__
    self._init_camera(camera_num, stereo_mode, stereo_decimate)
  File "/usr/lib/python3/dist-packages/picamera/camera.py", line 459, in _init_camera
    raise PiCameraError(
picamera.exc.PiCameraError: Camera is not enabled. Try running 'sudo raspi-config' and ensure that the camera has been enabled.

核心原因 #

picamera库是专门为树莓派官方CSI接口相机开发的，依赖树莓派的MMAL硬件加速框架，不支持外接USB相机。报错提示的内存不足是框架无法识别USB相机导致的误导性信息，实际问题是库与设备不兼容。

解决方法 #

方法1：使用命令行工具fswebcam（简单快速） #

• 先安装工具：

  sudo apt update && sudo apt install fswebcam
  

• 执行拍照命令（分辨率可自行调整）：

  fswebcam -r 1280x720 --no-banner test.jpg
  

方法2：使用Python的OpenCV库（适合编程场景） #

• 安装OpenCV依赖：

  sudo apt update && sudo apt install python3-opencv
  

• 替换为以下兼容USB相机的Python代码：

  import cv2
  import time
  
  # 打开第一个USB相机（参数0对应系统识别的第一个USB视频设备）
  cap = cv2.VideoCapture(0)
  # 等待相机完成初始化
  time.sleep(2)
  
  # 捕获图像
  ret, frame = cap.read()
  if ret:
      cv2.imwrite("test.jpg", frame)
      print("照片已保存为test.jpg")
  else:
      print("无法捕获图像，请检查相机连接")
  
  # 释放相机资源
  cap.release()
  

内容的提问来源于stack exchange，提问作者j ton