使用OpenCV2无法设置摄像头视频分辨率，请求尺寸已确认可用

数据老陈

2026-8-5

问题：OpenCV调用摄像头无法设置高分辨率，树莓派正常但笔记本失效

使用OpenCV2调用摄像头时只能捕获小尺寸图像，但通过Cheese和命令行工具uvcdynctrl可以确认摄像头支持更高分辨率。以下代码在树莓派上可正常运行，但在笔记本上失效：

import cv2
cap = cv2.VideoCapture(0)
cap.set(cv2.CAP_PROP_FRAME_WIDTH, 640)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 480)
width = cap.get(cv2.CAP_PROP_FRAME_WIDTH)
height = cap.get(cv2.CAP_PROP_FRAME_HEIGHT)
print(width, height)
# 输出：176.0 144.0

uvcdynctrl工具输出的摄像头支持格式及分辨率如下：

(base) ~/code/CaptureQueen$ uvcdynctrl -f
Listing available frame formats for device video0:
Pixel format: MJPG (Motion-JPEG; MIME type: image/jpeg)
  Frame size: 160x120
    Frame rates: 30, 25, 20, 15, 10, 5
  Frame size: 176x144
    Frame rates: 30, 25, 20, 15, 10, 5
  Frame size: 320x240
    Frame rates: 30, 25, 20, 15, 10, 5
  Frame size: 352x288
    Frame rates: 30, 25, 20, 15, 10, 5
  Frame size: 640x480
    Frame rates: 30, 25, 20, 15, 10, 5
  Frame size: 800x600
    Frame rates: 15, 10, 5
Pixel format: YUYV (YUYV 4:2:2; MIME type: video/x-raw-yuv)
  Frame size: 160x120
    Frame rates: 15, 10, 5
  Frame size: 176x144
    Frame rates: 15, 10, 5

解决方案

切换摄像头像素格式为MJPG：从uvcdynctrl输出可以看到，YUYV格式仅支持低分辨率，而MJPG格式支持640x480等高分辨率。OpenCV默认可能采用了YUYV格式，导致无法设置高分辨率。
修改后的代码：

import cv2
cap = cv2.VideoCapture(0)
# 设置像素格式为MJPG
cap.set(cv2.CAP_PROP_FOURCC, cv2.VideoWriter_fourcc('M', 'J', 'P', 'G'))
# 设置分辨率
cap.set(cv2.CAP_PROP_FRAME_WIDTH, 640)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 480)
# 验证设置结果
width = cap.get(cv2.CAP_PROP_FRAME_WIDTH)
height = cap.get(cv2.CAP_PROP_FRAME_HEIGHT)
print(width, height)