113 lines
3.9 KiB
Python
113 lines
3.9 KiB
Python
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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"""
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测试OpenCV VideoCapture的行为
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验证当设备索引不存在时VideoCapture的表现
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"""
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import cv2
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import time
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def test_video_capture_behavior():
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"""
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测试不同设备索引的VideoCapture行为
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"""
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print("=== OpenCV VideoCapture 行为测试 ===")
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print(f"OpenCV版本: {cv2.__version__}")
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print()
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# 测试不同的设备索引
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test_indices = [0, 1, 2, 3, -1]
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backends = [cv2.CAP_DSHOW, cv2.CAP_MSMF, cv2.CAP_ANY]
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backend_names = ['CAP_DSHOW', 'CAP_MSMF', 'CAP_ANY']
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for device_index in test_indices:
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print(f"\n--- 测试设备索引 {device_index} ---")
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for backend, backend_name in zip(backends, backend_names):
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print(f"\n后端: {backend_name}")
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try:
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start_time = time.time()
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cap = cv2.VideoCapture(device_index, backend)
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open_time = (time.time() - start_time) * 1000
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print(f" VideoCapture创建: 成功 (耗时: {open_time:.1f}ms)")
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print(f" isOpened(): {cap.isOpened()}")
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if cap.isOpened():
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# 尝试读取帧
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start_time = time.time()
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ret, frame = cap.read()
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read_time = (time.time() - start_time) * 1000
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print(f" read()返回值: ret={ret}")
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if ret and frame is not None:
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print(f" 帧形状: {frame.shape}")
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print(f" 读取耗时: {read_time:.1f}ms")
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else:
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print(f" 读取失败 (耗时: {read_time:.1f}ms)")
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# 获取一些属性
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try:
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width = cap.get(cv2.CAP_PROP_FRAME_WIDTH)
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height = cap.get(cv2.CAP_PROP_FRAME_HEIGHT)
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fps = cap.get(cv2.CAP_PROP_FPS)
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print(f" 分辨率: {int(width)}x{int(height)}")
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print(f" 帧率: {fps}")
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except Exception as e:
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print(f" 获取属性失败: {e}")
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else:
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print(" 相机未打开")
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cap.release()
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except Exception as e:
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print(f" 异常: {e}")
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print("\n=== 测试完成 ===")
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def test_specific_case():
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"""
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专门测试device_index=1的情况
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"""
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print("\n=== 专门测试 device_index=1 ===")
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try:
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# 使用DSHOW后端（Windows默认）
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cap = cv2.VideoCapture(1, cv2.CAP_DSHOW)
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print(f"VideoCapture(1, CAP_DSHOW) 创建成功")
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print(f"isOpened(): {cap.isOpened()}")
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if cap.isOpened():
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print("相机显示为已打开，但这可能是虚假的")
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# 尝试多次读取
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for i in range(3):
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print(f"\n第{i+1}次读取:")
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start_time = time.time()
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ret, frame = cap.read()
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read_time = (time.time() - start_time) * 1000
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print(f" ret: {ret}")
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print(f" frame is None: {frame is None}")
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print(f" 耗时: {read_time:.1f}ms")
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if ret and frame is not None:
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print(f" 帧形状: {frame.shape}")
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print(f" 帧数据类型: {frame.dtype}")
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print(f" 帧数据范围: {frame.min()} - {frame.max()}")
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else:
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print(" 读取失败或帧为空")
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break
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else:
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print("相机未打开")
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cap.release()
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except Exception as e:
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print(f"异常: {e}")
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if __name__ == "__main__":
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test_video_capture_behavior()
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test_specific_case() |