# Copyright (c) OpenMMLab. All rights reserved.
import logging
import sys
import time
import warnings
from contextlib import nullcontext
from threading import Thread
from typing import Dict, List, Optional, Tuple, Union
import cv2
from .nodes import NODES
from .utils import (BufferManager, EventManager, FrameMessage, ImageCapture,
VideoEndingMessage, is_image_file, limit_max_fps)
DEFAULT_FRAME_BUFFER_SIZE = 1
DEFAULT_INPUT_BUFFER_SIZE = 1
DEFAULT_DISPLAY_BUFFER_SIZE = 0
DEFAULT_USER_BUFFER_SIZE = 1
class WebcamRunner():
"""An interface for building webcam application from config.
Parameters:
name (str): Runner name.
camera_id (int | str): The camera ID (usually the ID of the default
camera is 0). Alternatively a file path or a URL can be given
to load from a video or image file.
camera_frame_shape (tuple, optional): Set the frame shape of the
camera in (width, height). If not given, the default frame shape
will be used. This argument is only valid when using a camera
as the input source. Default: None
camera_fps (int): Video reading maximum FPS. Default: 30
buffer_sizes (dict, optional): A dict to specify buffer sizes. The
key is the buffer name and the value is the buffer size.
Default: None
nodes (list): Node configs.
"""
def __init__(self,
name: str = 'Default Webcam Runner',
camera_id: Union[int, str] = 0,
camera_fps: int = 30,
camera_frame_shape: Optional[Tuple[int, int]] = None,
synchronous: bool = False,
buffer_sizes: Optional[Dict[str, int]] = None,
nodes: Optional[List[Dict]] = None):
# Basic parameters
self.name = name
self.camera_id = camera_id
self.camera_fps = camera_fps
self.camera_frame_shape = camera_frame_shape
self.synchronous = synchronous
# self.buffer_manager manages data flow between runner and nodes
self.buffer_manager = BufferManager()
# self.event_manager manages event-based asynchronous communication
self.event_manager = EventManager()
# self.node_list holds all node instance
self.node_list = []
# self.vcap is used to read camera frames. It will be built when the
# runner starts running
self.vcap = None
# Register runner events
self.event_manager.register_event('_exit_', is_keyboard=False)
if self.synchronous:
self.event_manager.register_event('_idle_', is_keyboard=False)
# Register nodes
if not nodes:
raise ValueError('No node is registered to the runner.')
# Register default buffers
if buffer_sizes is None:
buffer_sizes = {}
# _frame_ buffer
frame_buffer_size = buffer_sizes.get('_frame_',
DEFAULT_FRAME_BUFFER_SIZE)
self.buffer_manager.register_buffer('_frame_', frame_buffer_size)
# _input_ buffer
input_buffer_size = buffer_sizes.get('_input_',
DEFAULT_INPUT_BUFFER_SIZE)
self.buffer_manager.register_buffer('_input_', input_buffer_size)
# _display_ buffer
display_buffer_size = buffer_sizes.get('_display_',
DEFAULT_DISPLAY_BUFFER_SIZE)
self.buffer_manager.register_buffer('_display_', display_buffer_size)
# Build all nodes:
for node_cfg in nodes:
logging.info(f'Create node: {node_cfg.name}({node_cfg.type})')
node = NODES.build(node_cfg)
# Register node
self.node_list.append(node)
# Register buffers
for buffer_info in node.registered_buffers:
buffer_name = buffer_info.buffer_name
if buffer_name in self.buffer_manager:
continue
buffer_size = buffer_sizes.get(buffer_name,
DEFAULT_USER_BUFFER_SIZE)
self.buffer_manager.register_buffer(buffer_name, buffer_size)
logging.info(
f'Register user buffer: {buffer_name}({buffer_size})')
# Register events
for event_info in node.registered_events:
self.event_manager.register_event(
event_name=event_info.event_name,
is_keyboard=event_info.is_keyboard)
logging.info(f'Register event: {event_info.event_name}')
# Set runner for nodes
# This step is performed after node building when the runner has
# create full buffer/event managers and can
for node in self.node_list:
logging.info(f'Set runner for node: {node.name})')
node.set_runner(self)
def _read_camera(self):
"""Continually read video frames and put them into buffers."""
camera_id = self.camera_id
fps = self.camera_fps
# Build video capture
if is_image_file(camera_id):
self.vcap = ImageCapture(camera_id)
else:
self.vcap = cv2.VideoCapture(camera_id)
if self.camera_frame_shape is not None:
width, height = self.camera_frame_shape
self.vcap.set(cv2.CAP_PROP_FRAME_WIDTH, width)
self.vcap.set(cv2.CAP_PROP_FRAME_HEIGHT, height)
if not self.vcap.isOpened():
warnings.warn(f'Cannot open camera (ID={camera_id})')
sys.exit()
# Read video frames in a loop
first_frame = True
while not self.event_manager.is_set('_exit_'):
if self.synchronous:
if first_frame:
cm = nullcontext()
else:
# Read a new frame until the last frame has been processed
cm = self.event_manager.wait_and_handle('_idle_')
else:
# Read frames with a maximum FPS
cm = limit_max_fps(fps)
first_frame = False
with cm:
# Read a frame
ret_val, frame = self.vcap.read()
if ret_val:
# Put frame message (for display) into buffer `_frame_`
frame_msg = FrameMessage(frame)
self.buffer_manager.put('_frame_', frame_msg)
# Put input message (for model inference or other use)
# into buffer `_input_`
input_msg = FrameMessage(frame.copy())
input_msg.update_route_info(
node_name='Camera Info',
node_type='dummy',
info=self._get_camera_info())
self.buffer_manager.put_force('_input_', input_msg)
else:
# Put a video ending signal
self.buffer_manager.put('_frame_', VideoEndingMessage())
self.vcap.release()
def _display(self):
"""Continually obtain and display output frames."""
output_msg = None
while not self.event_manager.is_set('_exit_'):
while self.buffer_manager.is_empty('_display_'):
time.sleep(0.001)
# Set _idle_ to allow reading next frame
if self.synchronous:
self.event_manager.set('_idle_')
# acquire output from buffer
output_msg = self.buffer_manager.get('_display_')
# None indicates input stream ends
if isinstance(output_msg, VideoEndingMessage):
self.event_manager.set('_exit_')
break
img = output_msg.get_image()
# show in a window
cv2.imshow(self.name, img)
# handle keyboard input
key = cv2.waitKey(1)
if key != -1:
self._on_keyboard_input(key)
cv2.destroyAllWindows()
def _on_keyboard_input(self, key):
"""Handle the keyboard input."""
if key in (27, ord('q'), ord('Q')):
logging.info(f'Exit event captured: {key}')
self.event_manager.set('_exit_')
else:
logging.info(f'Keyboard event captured: {key}')
self.event_manager.set(key, is_keyboard=True)
def _get_camera_info(self):
"""Return the camera information in a dict."""
frame_width = self.vcap.get(cv2.CAP_PROP_FRAME_WIDTH)
frame_height = self.vcap.get(cv2.CAP_PROP_FRAME_HEIGHT)
frame_rate = self.vcap.get(cv2.CAP_PROP_FPS)
cam_info = {
'Camera ID': self.camera_id,
'Source resolution': f'{frame_width}x{frame_height}',
'Source FPS': frame_rate,
}
return cam_info
def run(self):
"""Program entry.
This method starts all nodes as well as video I/O in separate threads.
"""
try:
# Start node threads
non_daemon_nodes = []
for node in self.node_list:
node.start()
if not node.daemon:
non_daemon_nodes.append(node)
# Create a thread to read video frames
t_read = Thread(target=self._read_camera, args=())
t_read.start()
# Run display in the main thread
self._display()
logging.info('Display shut down')
# joint non-daemon nodes and runner threads
logging.info('Camera reading about to join')
t_read.join()
for node in non_daemon_nodes:
logging.info(f'Node {node.name} about to join')
node.join()
except KeyboardInterrupt:
pass
