Display text on frame

General
,
1

Hi. I am running the detection example from hailo-apps-infra repository. I ran the following code but no text are showing in the live frames, only the object label, bounding box, confidence and ID are shown. May I know what is missing from the code?

# Third-party imports
import gi
gi.require_version('Gst', '1.0')
from gi.repository import Gst
import cv2

# Local application-specific imports
import hailo
from hailo_apps.hailo_app_python.core.common.buffer_utils import get_caps_from_pad, get_numpy_from_buffer
from hailo_apps.hailo_app_python.core.gstreamer.gstreamer_app import app_callback_class
from hailo_apps.hailo_app_python.apps.detection.detection_pipeline import GStreamerDetectionApp
# endregion imports

# -----------------------------------------------------------------------------------------------
# User-defined class to be used in the callback function
# -----------------------------------------------------------------------------------------------
# Inheritance from the app_callback_class
class user_app_callback_class(app_callback_class):
    def __init__(self):
        super().__init__()
        self.video_width = 640
        self.video_height = 480
# -----------------------------------------------------------------------------------------------
# User-defined callback function
# -----------------------------------------------------------------------------------------------

# This is the callback function that will be called when data is available from the pipeline
def app_callback(pad, info, user_data):
    # Get the GstBuffer from the probe info
    buffer = info.get_buffer()
    # Check if the buffer is valid
    if buffer is None:
        return Gst.PadProbeReturn.OK

    # Using the user_data to count the number of frames
    user_data.increment()
    string_to_print = f"Frame count: {user_data.get_count()}\n"

    # Get the caps from the pad
    format, width, height = get_caps_from_pad(pad)
    
    # If the user_data.use_frame is set to True, we can get the video frame from the buffer
    frame = None
    if user_data.use_frame and format is not None and width is not None and height is not None:
        frame = get_numpy_from_buffer(buffer, format, width, height)

    roi = hailo.get_roi_from_buffer(buffer)
    detections = roi.get_objects_typed(hailo.HAILO_DETECTION)

    detection_count = 0
    for detection in detections:
        label = detection.get_label()
        bbox = detection.get_bbox()
        confidence = detection.get_confidence()
        if label == "person":
            track_id = 0
            track = detection.get_objects_typed(hailo.HAILO_UNIQUE_ID)
            if len(track) == 1:
                track_id = track[0].get_id()
            string_to_print += (f"Detection: ID: {track_id} Label: {label} Confidence: {confidence:.2f}\n")
            detection_count += 1
            
    if user_data.use_frame:
        cv2.putText(frame, f"Detections: {detection_count}", (10, 30), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 255, 0), 2)
        frame = cv2.cvtColor(frame, cv2.COLOR_RGB2BGR)
        user_data.set_frame(frame)

    #print(string_to_print)
    return Gst.PadProbeReturn.OK

if __name__ == "__main__":
    # Create an instance of the user app callback class
    user_data = user_app_callback_class()
    app = GStreamerDetectionApp(app_callback, user_data)
    app.run()
2

to show text in the main frame you have to change gstreamer
here is an example insert frame count in your hailo detection App
you can insert water mark text etc. just remember to do it after the hailo chain
to do it in callback function you have use –u on command line and the bounderings boxes from hailo are NOT set ind the frame. It will decrease the fps with 50% From my example you can set your on text and just make more layers it is not going to have a severe impact on output.