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Raspberry Pi Barcode Scanner with Webcam and Python
In this post, we will talk about building a Raspberry Pi barcode scanner with a USB webcam and Python by using Dynamsoft’s C/C++ barcode reader SDK.
Watch the video and see how the Raspberry Pi Barcode Scanner works:
How to Use Webcam with Raspberry Pi
To check whether the Linux system can identify the USB webcam, use the following commands:
lsusb
ls /dev/video*
Install fswebcam:
sudo apt-get install fswebcam
Take a picture from webcam:
fswebcam test.jpg
If the webcam can work well, you can take the next step.
Building Custom C/C++ Extension for Python
Get Dynamsoft Barcode Reader C/C++ SDK for Raspberry Pi Beta
Download free trial >
Extract the package and generate the symbolic link:
sudo ln -s <Your library path>/libDynamsoftBarcodeReader.so /usr/lib/libDynamsoftBarcodeReader.so
Create dbr.c in which you need to glue Dynamsoft Barcode Reader APIs to Python native code:
static PyObject *
initLicense(PyObject *self, PyObject *args)
{
char *license;
if (!PyArg_ParseTuple(args, "s", &license)) {
return NULL;
}
printf("License: %s\n", license);
int ret = DBR_InitLicense(license);
return Py_BuildValue("i", ret);
}
static PyObject *
decodeFile(PyObject *self, PyObject *args)
{
char *pFileName;
if (!PyArg_ParseTuple(args, "s", &pFileName)) {
return NULL;
}
// Dynamsoft Barcode Reader: init
__int64 llFormat = (OneD | QR_CODE | PDF417 | DATAMATRIX);
int iMaxCount = 0x7FFFFFFF;
ReaderOptions ro = {0};
pBarcodeResultArray pResults = NULL;
ro.llBarcodeFormat = llFormat;
ro.iMaxBarcodesNumPerPage = iMaxCount;
// Decode barcode image
int ret = DBR_DecodeFile(pFileName, &ro, &pResults);
printf("DecodeFile ret: %d\n", ret);
{
int count = pResults->iBarcodeCount;
pBarcodeResult* ppBarcodes = pResults->ppBarcodes;
pBarcodeResult tmp = NULL;
PyObject* list = PyList_New(count);
PyObject* result = NULL;
int i = 0;
for (; i < count; i++)
{
tmp = ppBarcodes[i];
result = PyString_FromString(tmp->pBarcodeData);
PyList_SetItem(list, i, Py_BuildValue("iN", (int)tmp->llFormat, result));
}
// release memory
DBR_FreeBarcodeResults(&pResults);
return list;
}
return Py_None;
}
static PyMethodDef Methods[] =
{
{"initLicense", initLicense, METH_VARARGS, NULL},
{"decodeFile", decodeFile, METH_VARARGS, NULL},
{NULL, NULL, 0, NULL}
};
PyMODINIT_FUNC
initdbr(void)
{
(void) Py_InitModule("dbr", Methods);
Create setup.py:
from distutils.core import setup, Extension
module_dbr = Extension('dbr',
sources = ['dbr.c'],
include_dirs=['/home/pi/Desktop/dbr/include'],
library_dirs=['/home/pi/Desktop/dbr/lib'],
libraries=['DynamsoftBarcodeReader'])
setup (name = 'DynamsoftBarcodeReader',
version = '1.0',
description = 'Python barcode extension',
ext_modules = [module_dbr])
Build and install the Python module:
python setup.py build
sudo python setup.py install
Note: if you see the error message “fatal error: Python.h: No such file or directory“, please install python-dev:
sudo apt-get install python-dev
Installing OpenCV on Raspbian Jessie
To capture images from a webcam, we can use OpenCV. Read the excellent article that demonstrates how to install OpenCV on Raspbian Jessie.
Raspberry Pi Barcode Scanner in Python
Create cam_reader.py:
cv2.namedWindow("preview")
vc = cv2.VideoCapture(0)
cache = ""
results = None
if vc.isOpened(): # try to get the first frame
initLicense("64E4EE3532B813C8EA8EA5F34E7B4528")
rval, frame = vc.read()
else:
rval = False
while rval:
cv2.imshow("preview", frame)
rval, frame = vc.read()
key = cv2.waitKey(20)
if key == ord('c'):
cache = getImageName()
cv2.imwrite(cache, frame)
results = decodeFile(cache)
print "Total count: " + str(len(results))
for result in results:
print "barcode format: " + formats[result[0]]
print "barcode value: " + result[1] + "\n*************************"
elif key == 27:
break
cv2.destroyWindow("preview")
Run the script:
python cam_reader.py
Capture and read barcode by pressing key ‘C’.
Source Code
https://github.com/dynamsoftlabs/webcam-barcode-scanner-for-pi