From 1f6be6f48cf3f083ccf6dd091f9c73e2e2de1c9a Mon Sep 17 00:00:00 2001
From: Théo de la Hogue
Date: Wed, 19 Jun 2024 18:32:50 +0200
Subject: Rewriting video streaming features to avoid lock.

---
 src/argaze/utils/contexts/TobiiProGlasses2.py | 88 +++++++++++++++------------
 1 file changed, 48 insertions(+), 40 deletions(-)

diff --git a/src/argaze/utils/contexts/TobiiProGlasses2.py b/src/argaze/utils/contexts/TobiiProGlasses2.py
index 98ac85a..e3c68b0 100644
--- a/src/argaze/utils/contexts/TobiiProGlasses2.py
+++ b/src/argaze/utils/contexts/TobiiProGlasses2.py
@@ -696,8 +696,8 @@ class LiveStream(ArFeatures.LiveProcessingContext):
 		container = av.open(f'rtsp://{self.__address}:8554/live/scene', options={'rtsp_transport': 'tcp'})
 		self.__stream = container.streams.video[0]
 
-		# Create a video buffer with a lock
-		self.__video_buffer = collections.OrderedDict()
+		# Create a single image buffer with a lock
+		self.__video_buffer = None
 		self.__video_buffer_lock = threading.Lock()
 
 		# Open video buffer reader
@@ -718,70 +718,78 @@ class LiveStream(ArFeatures.LiveProcessingContext):
 				logging.debug('> stop event is set')
 				break
 
-			if image is not None:
+			# Check image validity
+			if image is None:
 
-				if image.time is not None:
+				# Wait for half frame time
+				time.sleep(2 / self.__video_fps)
+				continue
+
+			# Check image time validity
+			if image.time is None:
+
+				# Wait for half frame time
+				time.sleep(2 / self.__video_fps)
+				continue
+
+			# Store first timestamp
+			if first_ts == 0:
+
+				first_ts = image.time
+
+			# Edit millisecond timestamp
+			timestamp = int((image.time - first_ts) * 1e3)
 
-					# Store first timestamp
-					if first_ts == 0:
-						first_ts = image.time
+			# Ignore image if buffer is locked
+			if not self.__video_buffer_lock.locked():
 
-					# Edit millisecond timestamp
-					timestamp = int((image.time - first_ts) * 1e3)
+				# Decode image
+				image = image.to_ndarray(format='bgr24')
+
+				# Lock buffer access
+				with self.__video_buffer_lock:
 
 					logging.debug('> store image at %i timestamp', timestamp)
 
-					# Lock buffer access
-					self.__video_buffer_lock.acquire()
+					# Store image with time index
+					self.__video_buffer= (timestamp, image)
 
-					# Decode image and store it at time index
-					self.__video_buffer[timestamp] = image.to_ndarray(format='bgr24')
+			else:
 
-					# Unlock buffer access
-					self.__video_buffer_lock.release()
+				logging.warning('%s.__stream_video: ignore image at %i', DataFeatures.get_class_path(self), timestamp)
 
 	def __video_buffer_read(self):
-		"""Read incoming buffered video images."""
+		"""Read incoming video buffer."""
 
 		logging.debug('%s.__video_buffer_read', DataFeatures.get_class_path(self))
 
 		while not self._stop_event.is_set():
 
-			# Can't read image while it is locked
-			while self.__video_buffer_lock.locked():
-				# Check 10 times per frame
-				time.sleep(1 / (10 * self.__video_fps))
+			# Wait for half frame time
+			time.sleep(2 / self.__video_fps)
 
 			# Lock buffer access
-			self.__video_buffer_lock.acquire()
-
-			# Video buffer not empty
-			if len(self.__video_buffer) > 0:
-
-				logging.debug('> %i images in buffer', len(self.__video_buffer))
+			with self.__video_buffer_lock:
 
-				# Get last stored image
-				try:
+				# Video buffer not empty
+				if self.__video_buffer is not None:
 
-					timestamp, image = self.__video_buffer.popitem(last=True)
+					timestamp, image = self.__video_buffer
 
 					logging.debug('> read image at %i timestamp', timestamp)
 
-					if len(self.__video_buffer) > 0:
-						logging.warning('skipping %i image', len(self.__video_buffer))
+					# Process video image
+					try:
 
-					# Clear buffer
-					self.__video_buffer = collections.OrderedDict()
-
-					# Process camera image
-					self._process_camera_image(timestamp=timestamp, image=image)
+						# Process camera image
+						self._process_camera_image(timestamp=timestamp, image=image)
 
-				except Exception as e:
+					except Exception as e:
 
-					logging.warning('%s.__video_buffer_read: %s', DataFeatures.get_class_path(self), e)
+						logging.warning('%s.__video_buffer_read: %s', DataFeatures.get_class_path(self), e)
 
-			# Unlock buffer access
-			self.__video_buffer_lock.release()
+					# Clear buffer
+					self.__video_buffer = None
 
 	def __keep_alive(self):
 		"""Maintain network connection."""
-- 
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