Python Pdfminer Unicode文本无法正确提取

Question

我正在尝试从unicode编码的pdf文件中提取sinhala文本。 但文字没有正确提取

PDF中的文字是： කවුරුහරිඔබෙන්ඇහුවොත්

提取的文字是： කවුරුහරිඔබෙන්ඇහුබොත්

一封信被另一封信取代。 这是我正在使用的代码。

import io
from pdfminer.pdfinterp import PDFResourceManager, PDFPageInterpreter
from pdfminer.converter import TextConverter
from pdfminer.layout import LAParams
from pdfminer.pdfpage import PDFPage


def convert_pdf_to_txt(path):
    rsrcmgr = PDFResourceManager()
    retstr = io.StringIO()
    codec = 'utf-8'
    laparams = LAParams()
    device = TextConverter(rsrcmgr, retstr, codec=codec, laparams=laparams)
    fp = open(path, 'rb')
    interpreter = PDFPageInterpreter(rsrcmgr, device)
    caching = True
    pagenos = set()

    for page in PDFPage.get_pages(fp, pagenos, maxpages=maxpages, password=password, caching=caching, check_extractable=True):
        interpreter.process_page(page)

    text = retstr.getvalue()

    fp.close()
    device.close()
    retstr.close()
    return text

u = convert_pdf_to_txt('sinhala.pdf')
print(u)