blakeblackshear.frigate/frigate/data_processing/post/license_plate.py

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"""Handle post processing for license plate recognition."""
import datetime
import logging
import cv2
import numpy as np
from peewee import DoesNotExist
from frigate.comms.embeddings_updater import EmbeddingsRequestEnum
from frigate.config import FrigateConfig
from frigate.data_processing.common.license_plate.mixin import (
WRITE_DEBUG_IMAGES,
LicensePlateProcessingMixin,
)
from frigate.data_processing.common.license_plate.model import (
LicensePlateModelRunner,
)
from frigate.data_processing.types import PostProcessDataEnum
from frigate.models import Recordings
from frigate.util.image import get_image_from_recording
from ..types import DataProcessorMetrics
from .api import PostProcessorApi
logger = logging.getLogger(__name__)
class LicensePlatePostProcessor(LicensePlateProcessingMixin, PostProcessorApi):
def __init__(
self,
config: FrigateConfig,
metrics: DataProcessorMetrics,
model_runner: LicensePlateModelRunner,
detected_license_plates: dict[str, dict[str, any]],
):
self.detected_license_plates = detected_license_plates
self.model_runner = model_runner
self.lpr_config = config.lpr
self.config = config
super().__init__(config, metrics, model_runner)
def __update_metrics(self, duration: float) -> None:
"""
Update inference metrics.
"""
self.metrics.alpr_pps.value = (self.metrics.alpr_pps.value * 9 + duration) / 10
def process_data(
self, data: dict[str, any], data_type: PostProcessDataEnum
) -> None:
"""Look for license plates in recording stream image
Args:
data (dict): containing data about the input.
data_type (enum): Describing the data that is being processed.
Returns:
None.
"""
start = datetime.datetime.now().timestamp()
event_id = data["event_id"]
camera_name = data["camera"]
if data_type == PostProcessDataEnum.recording:
obj_data = data["obj_data"]
frame_time = obj_data["frame_time"]
recordings_available_through = data["recordings_available"]
if frame_time > recordings_available_through:
logger.debug(
f"LPR post processing: No recordings available for this frame time {frame_time}, available through {recordings_available_through}"
)
elif data_type == PostProcessDataEnum.tracked_object:
# non-functional, need to think about snapshot time
obj_data = data["event"]["data"]
obj_data["id"] = data["event"]["id"]
obj_data["camera"] = data["event"]["camera"]
# TODO: snapshot time?
frame_time = data["event"]["start_time"]
else:
logger.error("No data type passed to LPR postprocessing")
return
recording_query = (
Recordings.select(
Recordings.path,
Recordings.start_time,
)
.where(
(
(frame_time >= Recordings.start_time)
& (frame_time <= Recordings.end_time)
)
)
.where(Recordings.camera == camera_name)
.order_by(Recordings.start_time.desc())
.limit(1)
)
try:
recording: Recordings = recording_query.get()
time_in_segment = frame_time - recording.start_time
codec = "mjpeg"
image_data = get_image_from_recording(
self.config.ffmpeg, recording.path, time_in_segment, codec, None
)
if not image_data:
logger.debug(
"LPR post processing: Unable to fetch license plate from recording"
)
# Convert bytes to numpy array
image_array = np.frombuffer(image_data, dtype=np.uint8)
if len(image_array) == 0:
logger.debug("LPR post processing: No image")
return
image = cv2.imdecode(image_array, cv2.IMREAD_COLOR)
except DoesNotExist:
logger.debug("Error fetching license plate for postprocessing")
return
if WRITE_DEBUG_IMAGES:
cv2.imwrite(f"debug/frames/lpr_post_{start}.jpg", image)
# convert to yuv for processing
frame = cv2.cvtColor(image, cv2.COLOR_BGR2YUV_I420)
detect_width = self.config.cameras[camera_name].detect.width
detect_height = self.config.cameras[camera_name].detect.height
# Scale the boxes based on detect dimensions
scale_x = image.shape[1] / detect_width
scale_y = image.shape[0] / detect_height
# Determine which box to enlarge based on detection mode
if self.requires_license_plate_detection:
# Scale and enlarge the car box
box = obj_data.get("box")
if not box:
return
# Scale original car box to detection dimensions
left = int(box[0] * scale_x)
top = int(box[1] * scale_y)
right = int(box[2] * scale_x)
bottom = int(box[3] * scale_y)
box = [left, top, right, bottom]
else:
# Get the license plate box from attributes
if not obj_data.get("current_attributes"):
return
license_plate = None
for attr in obj_data["current_attributes"]:
if attr.get("label") != "license_plate":
continue
if license_plate is None or attr.get("score", 0.0) > license_plate.get(
"score", 0.0
):
license_plate = attr
if not license_plate or not license_plate.get("box"):
return
# Scale license plate box to detection dimensions
orig_box = license_plate["box"]
left = int(orig_box[0] * scale_x)
top = int(orig_box[1] * scale_y)
right = int(orig_box[2] * scale_x)
bottom = int(orig_box[3] * scale_y)
box = [left, top, right, bottom]
width_box = right - left
height_box = bottom - top
# Enlarge box slightly to account for drift in detect vs recording stream
enlarge_factor = 0.3
new_left = max(0, int(left - (width_box * enlarge_factor / 2)))
new_top = max(0, int(top - (height_box * enlarge_factor / 2)))
new_right = min(image.shape[1], int(right + (width_box * enlarge_factor / 2)))
new_bottom = min(
image.shape[0], int(bottom + (height_box * enlarge_factor / 2))
)
keyframe_obj_data = obj_data.copy()
if self.requires_license_plate_detection:
# car box
keyframe_obj_data["box"] = [new_left, new_top, new_right, new_bottom]
else:
# Update the license plate box in the attributes
new_attributes = []
for attr in obj_data["current_attributes"]:
if attr.get("label") == "license_plate":
new_attr = attr.copy()
new_attr["box"] = [new_left, new_top, new_right, new_bottom]
new_attributes.append(new_attr)
else:
new_attributes.append(attr)
keyframe_obj_data["current_attributes"] = new_attributes
# run the frame through lpr processing
logger.debug(f"Post processing plate: {event_id}, {frame_time}")
self.lpr_process(keyframe_obj_data, frame)
self.__update_metrics(datetime.datetime.now().timestamp() - start)
def handle_request(self, topic, request_data) -> dict[str, any] | None:
if topic == EmbeddingsRequestEnum.reprocess_plate.value:
event = request_data["event"]
self.process_data(
{
"event_id": event["id"],
"camera": event["camera"],
"event": event,
},
PostProcessDataEnum.tracked_object,
)
return {
"message": "Successfully requested reprocessing of license plate.",
"success": True,
}