使用Python3 OpenCV+GStreamer调用Flir Hadron相机存显视频报错求助

尝试用Python 3结合OpenCV与GStreamer实现Flir Hadron相机的视频显示与保存，已有可正常运行的GStreamer管道能高分辨率显示并保存视频，但Python代码执行时报错Cannot open camera. Exiting，怀疑是相机设置代码问题，求解决。

可用的GStreamer管道（显示并保存视频） #

gst-launch-1.0 v4l2src io-mode=4 device=/dev/video0 do-timestamp=true ! tee name=t ! 'video/x-raw, format=UYVY, width=1920, height=1080, framerate=30/1' ! queue leaky=1 ! xvimagesink sync=false t. ! queue ! nvvidconv ! nvv4l2h265enc bitrate=8000000 ! h265parse ! qtmux ! filesink location=/home/nvidia/Desktop/RGB_$(date '+%Y-%m-%d_%H-%M-%S').mp4 -e 

我使用的Python 3代码 #

import time
import cv2

# Cam properties
fps = 30.
frame_width = 640
frame_height = 480
# Create capture
cap = cv2.VideoCapture(0)

# Set camera properties
cap.set(cv2.CAP_PROP_FRAME_WIDTH, frame_width)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, frame_height)
cap.set(cv2.CAP_PROP_FPS, fps)

# Define the gstreamer sink
gst_str_rtp = "appsrc ! videoconvert ! x264enc tune=zerolatency bitrate=500 speed-preset=superfast ! rtph264pay ! udpsink host=127.0.0.1 port=5000"


# Check if cap is open
if cap.isOpened() is not True:
    print "Cannot open camera. Exiting."
    quit()

# Create videowriter as a SHM sink
out = cv2.VideoWriter(gst_str_rtp, 0, fps, (frame_width, frame_height), True)

# Loop it
while True:
    # Get the frame
    ret, frame = cap.read()
    # Check
    if ret is True:
        # Flip frame
        frame = cv2.flip(frame, 1)
        # Write to SHM
        out.write(frame)
    else:
        print "Camera error."
        time.sleep(10)

cap.release()

解决方案 #

核心问题分析 #

1. OpenCV默认v4l2后端无法正确识别Flir Hadron相机的UYVY格式，必须通过GStreamer管道捕获帧
2. 代码存在Python 2语法错误（print未加括号），导致Python 3环境运行异常
3. 手动设置的640x480分辨率与相机原生1920x1080输出不匹配，引发格式冲突

修改后的完整代码 #

import time
import cv2

# 构造GStreamer捕获管道，适配相机UYVY格式并转为OpenCV兼容的BGR
gst_capture_str = (
    "v4l2src io-mode=4 device=/dev/video0 do-timestamp=true ! "
    "video/x-raw, format=UYVY, width=1920, height=1080, framerate=30/1 ! "
    "videoconvert ! video/x-raw, format=BGR ! appsink"
)

# 使用GStreamer后端初始化相机捕获
cap = cv2.VideoCapture(gst_capture_str, cv2.CAP_GSTREAMER)

# 检查相机是否成功打开
if not cap.isOpened():
    print("Cannot open camera. Exiting.")
    exit()

# 构造视频保存的GStreamer管道，复用原工作管道的硬件加速编码逻辑
gst_save_str = (
    "appsrc ! videoconvert ! nvvidconv ! "
    "nvv4l2h265enc bitrate=8000000 ! h265parse ! "
    "qtmux ! filesink location=/home/nvidia/Desktop/RGB_{}.mp4".format(time.strftime("%Y-%m-%d_%H-%M-%S"))
)

# 初始化视频写入器
out = cv2.VideoWriter(gst_save_str, cv2.CAP_GSTREAMER, 0, 30.0, (1920, 1080), True)

if not out.isOpened():
    print("Cannot open video writer. Exiting.")
    cap.release()
    exit()

# 主循环：读取、显示、保存帧
while True:
    ret, frame = cap.read()
    if ret:
        # 显示视频帧
        cv2.imshow("Flir Hadron Camera", frame)
        # 写入视频文件
        out.write(frame)
        # 按Q键退出循环
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break
    else:
        print("Failed to read frame from camera.")
        time.sleep(1)
        break

# 释放所有资源
cap.release()
out.release()
cv2.destroyAllWindows()

关键修改点 #

• 强制GStreamer后端捕获：直接传入匹配相机格式的GStreamer管道给cv2.VideoCapture，指定cv2.CAP_GSTREAMER后端，确保正确读取UYVY格式并转成OpenCV兼容的BGR
• 修复Python语法：将Python 2风格print语句改为Python 3的print()函数
• 匹配原生分辨率：使用相机实际输出的1920x1080分辨率，避免格式不兼容
• 复用硬件加速编码：视频保存管道沿用原工作管道的nvv4l2h265enc硬件编码器，提升编码效率
• 添加交互逻辑：增加窗口显示和按键退出功能，方便调试控制

额外验证步骤 #

运行以下代码确认OpenCV是否编译了GStreamer支持：

import cv2
print(cv2.getBuildInformation())

在输出中查找GStreamer条目，确保显示YES。

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