As @pvg mentioned in the comments, overriding load_resource function with your base64 functionality does the trick.

import base64,io

def load_resource(self, reason, filename):
    if reason == "image":
        if filename.startswith("http://") or filename.startswith("https://"):
            f = BytesIO(urlopen(filename).read())
        elif filename.startswith("data"):
            f = filename.split('base64,')[1]
            f = base64.b64decode(f)
            f = io.BytesIO(f)
        else:
            f = open(filename, "rb")
        return f
    else:
        self.error("Unknown resource loading reason \"%s\"" % reason)

EDIT :

This is a sample code to insert images into pdf. I commented some instructions in code.

from fpdf import FPDF
import os
import io
import base64


class PDF(FPDF):

    def load_resource(self, reason, filename):
        if reason == "image":
            if filename.startswith("http://") or filename.startswith("https://"):
                f = BytesIO(urlopen(filename).read())
            elif filename.startswith("data"):
                f = filename.split('base64,')[1]
                f = base64.b64decode(f)
                f = io.BytesIO(f)
            else:
                f = open(filename, "rb")
            return f
        else:
            self.error("Unknown resource loading reason \"%s\"" % reason)


    def sample_pdf(self,img,path):

        self.image(img,h=70,w=150,x=30,y=100,type="jpg")
        #make sure you use appropriate image format here jpg/png
        pdf.output(path, 'F')

if __name__ == '__main__':
    img = # pass your base64 image
    # you can find sample base64 here : https://pastebin.com/CaZJ7n6s

    pdf = PDF()
    pdf.add_page()
    pdf_path = # give path to where you want to save pdf
    pdf.sample_pdf(img,pdf_path) 

You can try making an Image object. Then in the src put the base64.

var myImage = new Image();
myImage.src="data:image/png;base64,"+file; 

pypdf does not implement any rendering functionality, thus you cannot apply it to your use-case here. The output you get is the internal representation of the PDF page used by pypdf.

If you just want to display the PDF file inside the web browser, I would probably go with the pdf.js library which does all the rendering on the frontend side.

If you really need image-based output, there are lots of libraries/tools which you could use:

• pdf2image, which is based upon the poppler library
• (Py)MuPDF
• Ghostscript
• pypdfium2
• pyvips
• ...

An example for pdf2image to get the first page as JPG data could look like this:

import base64
from io import BytesIO

import pdf2image


images = pdf2image.convert_from_path('file.pdf', first_page=1, last_page=1, fmt='jpg', use_pdftocairo=True)
image = images[0]
image_buffer = BytesIO()
image.save(image_buffer, format='JPEG')
image_data = base64.b64encode(image_buffer.getvalue())

For further options, like the resolution to use for rendering etc., see the corresponding upstream documentation.

In Imagemagick, you can do that with the INLINE: input structure. See http://www.imagemagick.org/Usage/files/#inline. For example:

convert 'inline:data:image/png;base64,
R0lGODlhIAAgAPIEAAAAAB6Q/76+vvXes////wAAAAAAAAAAACH5BAEAAAUALAAA
AAAgACAAAAOBWLrc/jDKCYG1NBcwegeaxHkeGD4j+Z1OWl4Yu6mAYAu1ebpwL/OE
YCDA0YWAQuJqRwsSeEyaRTUwTlxUqjUymmZpmeI3u62Mv+XWmUzBrpeit7YtB1/r
pTAefv942UcXVX9+MjNVfheGCl18i4ddjwwpPjEslFKDUWeRGj2fnw0JADs=
'  b64_noseguy.png

If you don't want to use the xmlrpclib's Binary class, you can just use the .encode() method of strings:

a = open("pdf_reference.pdf", "rb").read().encode("base64")

From my understanding base64decode only takes in a base64 string and looks like you have some headers on your string that are not encoded.

I would remove "data:application/pdf;base64,"

check out the doc here: https://docs.python.org/2/library/base64.html

When I've used it in the past, I have only used the encoded string.