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Python API Reference - BarcodeReader Video Methods

Method Description
start_video_mode Starts a new thread to decode barcodes from the inner frame queue.
append_video_frame Appends a frame image buffer to the inner frame queue.
stop_video_mode Stops the frame decoding thread created by start_video_mode().
init_frame_decoding_parameters Initializes frame decoding parameters.
get_length_of_frame_queue Gets length of current inner frame queue.

start_video_mode

Starts a new thread to decode barcodes from the inner frame queue.

BarcodeReader.start_video_mode(frame_decoding_parameters, text_result_callback_func, template_name="", intermediate_result_callback_func=None, error_callback_func=None, unique_barcode_callback_func=None, user_data=None)

Parameters

[in] frame_decoding_parameters <class FrameDecodingParameters> : The frame decoding parameters. You can get it by using init_frame_decoding_parameters() then modifying its parameters’ value.

[in] text_result_callback_func <function pointer> : Sets callback function to process text results which is triggered when the library finishes decoding a frame.

This callback function pointer must follow the following format: callback_func_name(frameId, results, user_data);

[in] template_name (optional)<str> : The template name.

[in] intermediate_result_callback_func (optional)<function pointer> : Sets callback function to process intermediate results which is triggered when the library finishes decoding a frame.

This callback function pointer must follow the following format: callback_func_name(frameId, results, user_data);

[in] error_callback_func (optional)<function pointer> : Sets callback function to process errors which is triggered when the library finishes decoding a frame.

This callback function pointer must follow the following format: callback_func_name(frameId, error, user_data);

[in] unique_barcode_callback_func <function pointer> : Sets callback function to process unique barcode results which is triggered when the library finishes decoding a frame and finds unique barcodes.

This callback function pointer must follow the following format: callback_func_name(frameId, results, user_data);

[in] user_data (optional)<object> : Customizes arguments passed to your function.

Exception
BarcodeReaderError : If error happens, this function will throw a BarcodeReaderError exception that can report the detailed error message.

Code Snippet

import cv2
from dbr import *

# The callback function for receiving barcode results
def text_results_callback_func(frame_id, t_results, user_data):
    print(frame_id)
    for result in t_results:
        text_result = TextResult(result)
        print("Barcode Format : ")
        print(text_result.barcode_format_string)
        print("Barcode Text : ")
        print(text_result.barcode_text)
        print("Localization Points : ")
        print(text_result.localization_result.localization_points)
        print("Exception : ")
        print(text_result.exception)
        print("-------------")

# The callback function for receiving unique barcode results
def unique_barcode_callback_func(frame_id, results, user_data):
    print(frame_id)
    for result in results:
        unique_text_result = TextResult(result)
        # Add your code to process unique barcode result

# The callback function for receiving intermediate results
def intermediate_results_callback_func(frame_id, results, user_data):
    print(frame_id)
    for result in results:
        intermediate_result = IntermediateResult(result)
        # Add your code to process intermediate result

# The callback function for receiving error
def error_callback_func(frame_id, error, user_data):
    # Add your code to process error

def get_time():
    localtime = time.localtime()
    capturetime = time.strftime("%Y%m%d%H%M%S", localtime)
    return capturetime

def read_barcode():
    video_width = 0
    video_height = 0
    
    vc = cv2.VideoCapture(0)
    video_width  = vc.get(cv2.CAP_PROP_FRAME_WIDTH)
    video_height = vc.get(cv2.CAP_PROP_FRAME_HEIGHT)
    vc.set(3, video_width) #set width
    vc.set(4, video_height) #set height

    stride = 0
    if vc.isOpened():  
        rval, frame = vc.read()
        stride = frame.strides[0]
    else:
        return

    windowName = "Barcode Reader"

    parameters = reader.init_frame_decoding_parameters()
    # you can modify these following parameters.
    parameters.max_queue_length = 30
    parameters.max_result_queue_length = 30
    parameters.width = video_width
    parameters.height = video_height
    parameters.stride = stride
    parameters.image_pixel_format = EnumImagePixelFormat.IPF_RGB_888
    parameters.region_top = 0
    parameters.region_bottom = 100
    parameters.region_left = 0
    parameters.region_right = 100
    parameters.region_measured_by_percentage = 1
    parameters.threshold = 0.01
    parameters.fps = 0
    parameters.auto_filter = 1

    # reader.start_video_mode(parameters, text_results_callback_func, "", intermediate_results_callback_func, error_callback_func, unique_barcode_callback_func)
    reader.start_video_mode(parameters, text_results_callback_func)

    while True:
        cv2.imshow(windowName, frame)
        rval, frame = vc.read()
        if rval == False:
            break
        
        try:
            ret = reader.append_video_frame(frame)
        except:
            pass
        
        # 'ESC' for quit
        key = cv2.waitKey(1)
        if key == 27:
            break

    reader.stop_video_mode()
    cv2.destroyWindow(windowName)

print("-------------------start------------------------")

license_key = 'YOUR-LICENSE-KEY'
BarcodeReader.init_license(license_key)
reader = BarcodeReader.get_instance()
if reader != None:
    read_barcode()
    reader.recycle_instance()

print("-------------------over------------------------")

append_video_frame

Appends a frame image buffer to the inner frame queue.

BarcodeReader.append_video_frame(video_frame)

Parameters
[in] video_frame : Gets video frame by opencv.

Return Value
The current frame ID.

stop_video_mode

Stop the frame decoding thread created by start_video_mode

BarcodeReader.stop_video_mode()

Exception
BarcodeReaderError : If error happens, this function will throw a BarcodeReaderError exception that can report the detailed error message.

init_frame_decoding_parameters

Initializes frame decoding parameters with default values.

BarcodeReader.init_frame_decoding_parameters()

Return Value
frame_decoding_parameters <class FrameDecodingParameters> : The frame decoding parameters.

get_length_of_frame_queue

Gets the current length of the inner frame queue.

BarcodeReader.get_length_of_frame_queue()

Return Value
Returns the length of the inner frame queue.

This page is compatible for:

Version 7.5.0

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