add new files

Author: neozhaoliang

base_thread.py

@@ -0,0 +1,52 @@
+from queue import Queue
+import cv2
+from PyQt5.QtCore import (QThread, QTime, QMutex, pyqtSignal, QMutexLocker)
+
+from structures import ThreadStatisticsData
+
+
+class BaseThread(QThread):
+
+    """
+    Base class for all types of threads (capture, processing, stitching, ...,
+    etc). Mainly for collecting statistics of this thread.
+    """
+
+    FPS_STAT_QUEUE_LENGTH = 32
+
+    update_statistics_gui = pyqtSignal(ThreadStatisticsData)
+
+    def __init__(self, parent=None):
+        super(BaseThread, self).__init__(parent)
+        self.init_commons()
+
+    def init_commons(self):
+        self.stopped = False
+        self.stop_mutex = QMutex()
+        self.clock = QTime()
+        self.fps = Queue()
+        self.processing_time = 0
+        self.processing_mutex = QMutex()
+        self.fps_sum = 0
+        self.stat_data = ThreadStatisticsData()
+
+    def stop(self):
+        with QMutexLocker(self.stop_mutex):
+            self.stopped = True
+
+    def update_fps(self, dt):
+        # add instantaneous fps value to queue
+        if dt > 0:
+            self.fps.put(1000 / dt)
+
+        # discard redundant items in the fps queue
+        if self.fps.qsize() > self.FPS_STAT_QUEUE_LENGTH:
+            self.fps.get()
+
+        # update statistics
+        if self.fps.qsize() == self.FPS_STAT_QUEUE_LENGTH:
+            while not self.fps.empty():
+                self.fps_sum += self.fps.get()
+
+            self.stat_data.average_fps = round(self.fps_sum / self.FPS_STAT_QUEUE_LENGTH, 2)
+            self.fps_sum = 0

capture_thread.py

@@ -0,0 +1,108 @@
+import cv2
+from PyQt5.QtCore import qDebug
+
+from base_thread import BaseThread
+from structures import ImageFrame
+from utils import gstreamer_pipeline
+
+
+class CaptureThread(BaseThread):
+
+    def __init__(self,
+                 device_id,
+                 flip_method=2,
+                 drop_if_full=True,
+                 api_preference=cv2.CAP_GSTREAMER,
+                 resolution=None,
+                 parent=None):
+        """
+        device_id: device number of the camera.
+        flip_method: 0 for identity, 2 for 180 degree rotation (if the camera is installed
+            up-side-down).
+        drop_if_full: drop the frame if buffer is full.
+        api_preference: cv2.CAP_GSTREAMER for csi cameras, usually cv2.CAP_ANY would suffice.
+        resolution: camera resolution (width, height).
+        """
+        super(CaptureThread, self).__init__(parent)
+        self.device_id = device_id
+        self.flip_method = flip_method
+        self.drop_if_full = drop_if_full
+        self.api_preference = api_preference
+        self.resolution = resolution
+        self.cap = cv2.VideoCapture()
+        # an instance of the MultiBufferManager object,
+        # for synchronizing this thread with other cameras.
+        self.buffer_manager = None
+
+    def run(self):
+        if self.buffer_manager is None:
+            raise ValueError("This thread has not been binded to any buffer manager yet")
+
+        while True:
+            self.stop_mutex.lock()
+            if self.stopped:
+                self.stopped = False
+                self.stop_mutex.unlock()
+                break
+            self.stop_mutex.unlock()
+
+            # save capture time
+            self.processing_time = self.clock.elapsed()
+            # start timer (used to calculate capture rate)
+            self.clock.start()
+
+            # synchronize with other streams (if enabled for this stream)
+            self.buffer_manager.sync(self.device_id)
+
+            if not self.cap.grab():
+                continue
+
+            # retrieve frame and add it to buffer
+            _, frame = self.cap.retrieve()
+            img_frame = ImageFrame(self.clock.msecsSinceStartOfDay(), frame)
+            self.buffer_manager.get_device(self.device_id).add(img_frame, self.drop_if_full)
+
+            # update statistics
+            self.update_fps(self.processing_time)
+            self.stat_data.frames_processed_count += 1
+            # inform GUI of updated statistics
+            self.update_statistics_gui.emit(self.stat_data)
+
+        qDebug("Stopping capture thread...")
+
+    def connect_camera(self):
+        options = gstreamer_pipeline(cam_id=self.device_id, flip_method=self.flip_method)
+        self.cap.open(options, self.api_preference)
+        # return false if failed to open camera
+        if not self.cap.isOpened():
+            qDebug("Cannot open camera {}".format(self.device_id))
+            return False
+        else:
+            # try to set camera resolution
+            if self.resolution is not None:
+                width, height = self.resolution
+                self.cap.set(cv2.CAP_PROP_FRAME_WIDTH, width)
+                self.cap.set(cv2.CAP_PROP_FRAME_HEIGHT, height)
+                # some camera may become closed if the resolution is not supported
+                if not self.cap.isOpened():
+                    qDebug("Resolution not supported by camera device: {}".format(self.resolution))
+                    return False
+            # use the default resolution
+            else:
+                width = int(self.cap.get(cv2.CAP_PROP_FRAME_WIDTH))
+                height = int(self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
+                self.resolution = (width, height)
+
+        return True
+
+    def disconnect_camera(self):
+        # disconnect camera if it's already openned.
+        if self.cap.isOpened():
+            self.cap.release()
+            return True
+        # else do nothing and return
+        else:
+            return False
+
+    def is_camera_connected(self):
+        return self.cap.isOpened()