use a thread to capture frames from the subprocess so it can be killed properly

This commit is contained in:
blakeblackshear 2019-07-17 22:25:59 -05:00 committed by Blake Blackshear
parent c9e9f7a735
commit 700bd1e3ef

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@ -12,60 +12,6 @@ from . object_detection import FramePrepper
from . objects import ObjectCleaner, BestPersonFrame
from . mqtt import MqttObjectPublisher
# fetch the frames as fast a possible and store current frame in a shared memory array
def fetch_frames(shared_arr, shared_frame_time, frame_lock, frame_ready, frame_shape, rtsp_url, take_frame=1, ffmpeg_hwaccel_args=[]):
# convert shared memory array into numpy and shape into image array
arr = tonumpyarray(shared_arr).reshape(frame_shape)
frame_size = frame_shape[0] * frame_shape[1] * frame_shape[2]
ffmpeg_global_args = [
'-hide_banner', '-loglevel', 'panic'
]
ffmpeg_input_args = [
'-avoid_negative_ts', 'make_zero',
'-fflags', 'nobuffer',
'-flags', 'low_delay',
'-strict', 'experimental',
'-fflags', '+genpts',
'-rtsp_transport', 'tcp',
'-stimeout', '5000000',
'-use_wallclock_as_timestamps', '1'
]
ffmpeg_cmd = (['ffmpeg'] +
ffmpeg_global_args +
ffmpeg_hwaccel_args +
ffmpeg_input_args +
['-i', rtsp_url,
'-f', 'rawvideo',
'-pix_fmt', 'rgb24',
'pipe:'])
print(" ".join(ffmpeg_cmd))
pipe = sp.Popen(ffmpeg_cmd, stdout = sp.PIPE, bufsize=frame_size)
frame_num = 0
while True:
raw_image = pipe.stdout.read(frame_size)
frame_num += 1
if (frame_num % take_frame) != 0:
continue
frame = (
np
.frombuffer(raw_image, np.uint8)
.reshape(frame_shape)
)
with frame_lock:
shared_frame_time.value = datetime.datetime.now().timestamp()
arr[:] = frame
# Notify with the condition that a new frame is ready
with frame_ready:
frame_ready.notify_all()
pipe.stdout.flush()
# Stores 2 seconds worth of frames when motion is detected so they can be used for other threads
class FrameTracker(threading.Thread):
def __init__(self, shared_frame, frame_time, frame_ready, frame_lock, recent_frames):
@ -125,13 +71,48 @@ class CameraWatchdog(threading.Thread):
while True:
# wait a bit before checking
time.sleep(60)
time.sleep(10)
if (datetime.datetime.now().timestamp() - self.camera.shared_frame_time.value) > 2:
if (datetime.datetime.now().timestamp() - self.camera.frame_time.value) > 2:
print("last frame is more than 2 seconds old, restarting camera capture...")
self.camera.start_or_restart_capture()
time.sleep(5)
# Thread to read the stdout of the ffmpeg process and update the current frame
class CameraCapture(threading.Thread):
def __init__(self, camera):
threading.Thread.__init__(self)
self.camera = camera
def run(self):
frame_num = 0
while True:
if self.camera.ffmpeg_process.poll() != None:
print("ffmpeg process is not running. exiting capture thread...")
break
raw_image = self.camera.ffmpeg_process.stdout.read(self.camera.frame_size)
if len(raw_image) == 0:
print("ffmpeg didnt return a frame. something is wrong. exiting capture thread...")
break
frame_num += 1
if (frame_num % self.camera.take_frame) != 0:
continue
with self.camera.frame_lock:
self.camera.frame_time.value = datetime.datetime.now().timestamp()
self.camera.current_frame[:] = (
np
.frombuffer(raw_image, np.uint8)
.reshape(self.camera.frame_shape)
)
# Notify with the condition that a new frame is ready
with self.camera.frame_ready:
self.camera.frame_ready.notify_all()
class Camera:
def __init__(self, name, config, prepped_frame_queue, mqtt_client, mqtt_prefix):
self.name = name
@ -143,15 +124,14 @@ class Camera:
self.ffmpeg_hwaccel_args = self.config.get('ffmpeg_hwaccel_args', [])
self.regions = self.config['regions']
self.frame_shape = get_frame_shape(self.rtsp_url)
self.frame_size = self.frame_shape[0] * self.frame_shape[1] * self.frame_shape[2]
self.mqtt_client = mqtt_client
self.mqtt_topic_prefix = '{}/{}'.format(mqtt_prefix, self.name)
# compute the flattened array length from the shape of the frame
flat_array_length = self.frame_shape[0] * self.frame_shape[1] * self.frame_shape[2]
# create shared array for storing the full frame image data
self.shared_frame_array = mp.Array(ctypes.c_uint8, flat_array_length)
# create a numpy array for the current frame in initialize to zeros
self.current_frame = np.zeros(self.frame_shape, np.uint8)
# create shared value for storing the frame_time
self.shared_frame_time = mp.Value('d', 0.0)
self.frame_time = mp.Value('d', 0.0)
# Lock to control access to the frame
self.frame_lock = mp.Lock()
# Condition for notifying that a new frame is ready
@ -159,10 +139,8 @@ class Camera:
# Condition for notifying that objects were parsed
self.objects_parsed = mp.Condition()
# shape current frame so it can be treated as a numpy image
self.shared_frame_np = tonumpyarray(self.shared_frame_array).reshape(self.frame_shape)
self.capture_process = None
self.ffmpeg_process = None
self.capture_thread = None
# for each region, create a separate thread to resize the region and prep for detection
self.detection_prep_threads = []
@ -175,8 +153,8 @@ class Camera:
region['threshold'] = 0.5
self.detection_prep_threads.append(FramePrepper(
self.name,
self.shared_frame_np,
self.shared_frame_time,
self.current_frame,
self.frame_time,
self.frame_ready,
self.frame_lock,
region['size'], region['x_offset'], region['y_offset'], region['threshold'],
@ -184,7 +162,7 @@ class Camera:
))
# start a thread to store recent motion frames for processing
self.frame_tracker = FrameTracker(self.shared_frame_np, self.shared_frame_time,
self.frame_tracker = FrameTracker(self.current_frame, self.frame_time,
self.frame_ready, self.frame_lock, self.recent_frames)
self.frame_tracker.start()
@ -215,20 +193,51 @@ class Camera:
def start_or_restart_capture(self):
if not self.capture_process is None:
print("Terminating the existing capture process...")
self.capture_process.terminate()
del self.capture_process
self.capture_process = None
if not self.ffmpeg_process is None:
print("Killing the existing ffmpeg process...")
self.ffmpeg_process.kill()
self.ffmpeg_process.wait()
print("Waiting for the capture thread to exit...")
self.capture_thread.join()
self.ffmpeg_process = None
self.capture_thread = None
# create the process to capture frames from the RTSP stream and store in a shared array
print("Creating a new capture process...")
self.capture_process = mp.Process(target=fetch_frames, args=(self.shared_frame_array,
self.shared_frame_time, self.frame_lock, self.frame_ready, self.frame_shape,
self.rtsp_url, self.take_frame, self.ffmpeg_hwaccel_args))
self.capture_process.daemon = True
print("Starting a new capture process...")
self.capture_process.start()
print("Creating a new ffmpeg process...")
self.start_ffmpeg()
print("Creating a new capture thread...")
self.capture_thread = CameraCapture(self)
print("Starting a new capture thread...")
self.capture_thread.start()
def start_ffmpeg(self):
ffmpeg_global_args = [
'-hide_banner', '-loglevel', 'panic'
]
ffmpeg_input_args = [
'-avoid_negative_ts', 'make_zero',
'-fflags', 'nobuffer',
'-flags', 'low_delay',
'-strict', 'experimental',
'-fflags', '+genpts',
'-rtsp_transport', 'tcp',
'-stimeout', '5000000',
'-use_wallclock_as_timestamps', '1'
]
ffmpeg_cmd = (['ffmpeg'] +
ffmpeg_global_args +
self.ffmpeg_hwaccel_args +
ffmpeg_input_args +
['-i', self.rtsp_url,
'-f', 'rawvideo',
'-pix_fmt', 'rgb24',
'pipe:'])
print(" ".join(ffmpeg_cmd))
self.ffmpeg_process = sp.Popen(ffmpeg_cmd, stdout = sp.PIPE, bufsize=self.frame_size)
def start(self):
self.start_or_restart_capture()
@ -238,10 +247,10 @@ class Camera:
self.watchdog.start()
def join(self):
self.capture_process.join()
self.capture_thread.join()
def get_capture_pid(self):
return self.capture_process.pid
return self.ffmpeg_process.pid
def add_objects(self, objects):
if len(objects) == 0:
@ -291,7 +300,7 @@ class Camera:
detected_objects = self.detected_objects.copy()
# lock and make a copy of the current frame
with self.frame_lock:
frame = self.shared_frame_np.copy()
frame = self.current_frame.copy()
# draw the bounding boxes on the screen
for obj in detected_objects: