Python – 在子线程中使用OpenCV异步读取摄像头视频帧传递到主线程中进行处理
一般情况下,我们会在主线程中直接使用opencv打开摄像头然后读取的视频帧进行操作,这种方式是阻塞的,如果我们想要在主线程读取摄像头视频帧的时候还进行其他的操作会非常不方便。这个时候有必要将读取摄像头视频帧的这一部分代码移动到子线程中,然后通过队列使得主线程可以获取摄像头的视频帧,同时也不会阻塞主线程。
1 子线程使用OpenCV读取摄像头视频帧
<code class="language-python line-numbers">import cv2 import threading from queue import Queue class ReadCameraThread(threading.Thread): def __init__(self, video_queue): super(ReadCameraThread).__init__() threading.Thread.__init__(self) self.read_capture = cv2.VideoCapture(0) self.video_queue = video_queue self.running = True def run(self): if not self.read_capture.isOpened(): print('未检测到摄像头') exit(0) while self.read_capture.isOpened() and self.running: ret, frame = self.read_capture.read() if not ret: break self.video_queue.put(frame) print('put the frame') self.read_capture.release() cv2.destroyAllWindows() def stop_read_camera(self): self.running = False </code>
2 主线程中从缓存队列读取视频帧
<code class="language-python line-numbers">class StreamingOnlineRecognize: def __init__(self): self.video_queue = Queue() self.video_stream_in = ReadCameraThread(self.video_queue) self.video_stream_in.start() def start(self): self._running = True while self._running: if not self.video_queue.empty(): frame = self.video_queue.get() print('get the frame') if frame is not None: cv2.imshow('test', frame) cv2.waitKey(1) else: print('the size of self.video_queue is <= 0') cv2.destroyAllWindows() self.video_stream_in.join() </code>
3 完整示例
<code class="language-python line-numbers"># -*- coding: utf-8 -*- import cv2 import threading from queue import Queue class ReadCameraThread(threading.Thread): def __init__(self, video_queue): super(ReadCameraThread).__init__() threading.Thread.__init__(self) self.read_capture = cv2.VideoCapture(0) self.video_queue = video_queue self.running = True def run(self): if not self.read_capture.isOpened(): print('未检测到摄像头') exit(0) while self.read_capture.isOpened() and self.running: ret, frame = self.read_capture.read() if not ret: break self.video_queue.put(frame) print('put the frame') self.read_capture.release() cv2.destroyAllWindows() def stop_read_camera(self): self.running = False class StreamingOnlineRecognize: def __init__(self): self.video_queue = Queue() self.video_stream_in = ReadCameraThread(self.video_queue) self.video_stream_in.start() def start(self): self._running = True while self._running: if not self.video_queue.empty(): frame = self.video_queue.get() print('get the frame') if frame is not None: cv2.imshow('test', frame) cv2.waitKey(1) else: print('the size of self.video_queue is <= 0') cv2.destroyAllWindows() self.video_stream_in.join() if __name__ == '__main__': streaming_online_recognize = StreamingOnlineRecognize() streaming_online_recognize.start() </code>
本文作者:StubbornHuang
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原文标题:Python – 在子线程中使用OpenCV异步读取摄像头视频帧传递到主线程中进行处理
原文链接:https://www.stubbornhuang.com/2318/
发布于:2022年08月19日 8:36:20
修改于:2023年06月21日 18:16:18
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