Minimal example of how to create a working Anki deck with a media file embedded.

genanki-media-test.py

import genanki

my_model = genanki.Model(
  1380120064,
  'Example',
  fields=[
    {'name': 'Object'},
    {'name': 'Image'},
  ],
  templates=[
    {
      'name': 'Card 1',
      'qfmt': '{{Object}}',
      'afmt': '{{FrontSide}}<hr id="answer">{{Image}}',
    },
  ])

my_note = genanki.Note(
  model=my_model,
  fields=['JPEG File', '<img src="format.jpg" />'])

my_deck = genanki.Deck(
  2059400191,
  'Example')

my_deck.add_note(my_note)

my_package = genanki.Package(my_deck)
my_package.media_files = ['format.jpg']

my_package.write_to_file('output.apkg')

Thank you so much for the example, @jlumbroso ! However, I am getting "format.jpg" doesn't exist. Where did you place that file ? In the root of your drive ?