a bytes-like object is required, not 'str' в videokit

Доброго времени суток. Нашел приложение для конвертации видео + celery что очень радует. Не радует только то что оно отказывается работать под python3

Трейсбек прикладываю:

 File "/home/django/venv/example/lib/python3.5/site-packages/django/core/handlers/exception.py", line 39, in inner
    response = get_response(request)
  File "/home/django/venv/example/lib/python3.5/site-packages/django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/home/django/venv/example/lib/python3.5/site-packages/django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/django/example/media/views.py", line 32, in item_create
    media_item.save()
  File "/home/django/venv/example/lib/python3.5/site-packages/django/db/models/base.py", line 796, in save
    force_update=force_update, update_fields=update_fields)
  File "/home/django/venv/example/lib/python3.5/site-packages/django/db/models/base.py", line 824, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "/home/django/venv/example/lib/python3.5/site-packages/django/db/models/base.py", line 908, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "/home/django/venv/example/lib/python3.5/site-packages/django/db/models/base.py", line 947, in _do_insert
    using=using, raw=raw)
  File "/home/django/venv/example/lib/python3.5/site-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/django/venv/example/lib/python3.5/site-packages/django/db/models/query.py", line 1045, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/home/django/venv/example/lib/python3.5/site-packages/django/db/models/sql/compiler.py", line 1053, in execute_sql
    for sql, params in self.as_sql():
  File "/home/django/venv/example/lib/python3.5/site-packages/django/db/models/sql/compiler.py", line 1006, in as_sql
    for obj in self.query.objs
  File "/home/django/venv/example/lib/python3.5/site-packages/django/db/models/sql/compiler.py", line 1006, in <listcomp>
    for obj in self.query.objs
  File "/home/django/venv/example/lib/python3.5/site-packages/django/db/models/sql/compiler.py", line 1005, in <listcomp>
    [self.prepare_value(field, self.pre_save_val(field, obj)) for field in fields]
  File "/home/django/venv/example/lib/python3.5/site-packages/django/db/models/sql/compiler.py", line 955, in pre_save_val
    return field.pre_save(obj, add=True)
  File "/home/django/venv/example/lib/python3.5/site-packages/django/db/models/fields/files.py", line 292, in pre_save
    file.save(file.name, file, save=False)
  File "/home/django/venv/example/lib/python3.5/site-packages/django/db/models/fields/files.py", line 92, in save
    setattr(self.instance, self.field.name, self.name)
  File "/home/django/example/videokit/fields.py", line 198, in __set__
    self.field.update_dimension_fields(instance, force = True)
  File "/home/django/example/videokit/models.py", line 119, in update_dimension_fields
    width = file.width
  File "/home/django/example/videokit/fields.py", line 133, in _get_width
    return self._get_video_dimensions()[0]
  File "/home/django/example/videokit/fields.py", line 164, in _get_video_dimensions
    self._dimensions_cache = get_video_dimensions(self)
  File "/home/django/example/videokit/fields.py", line 25, in get_video_dimensions
    width = stdout.strip(' \t\n\r')
TypeError: a bytes-like object is required, not 'str'
[09/Dec/2018 18:34:05] "POST /item_create/ HTTP/1.1" 500 151897

И функцию в которой ошибка:

from django.conf import settings
from django.core.files import File
from django.db.models.fields.files import FieldFile
from django.db.models.fields.files import FileDescriptor

from datetime import datetime
import hashlib
import os.path
import subprocess

from videokit.apps import VideokitConfig
from videokit.tasks import generate_video

def get_video_dimensions(file):
    path = os.path.join(settings.MEDIA_ROOT, file.name)

    if os.path.isfile(path):
        try:
            process = subprocess.Popen(
                ['mediainfo', '--Inform=Video;%Width%', path],
                stdout = subprocess.PIPE, stderr = subprocess.PIPE)

            stdout, stderr = process.communicate()
            if process.wait() == 0:
                width = int(stdout.strip(' \t\n\r'))
            else:
                return (0,0)

            process = subprocess.Popen(
                ['mediainfo', '--Inform=Video;%Height%', path],
                stdout = subprocess.PIPE, stderr = subprocess.PIPE)

            stdout, stderr = process.communicate()
            if process.wait() == 0:
                height = int(stdout.strip(' \t\n\r'))
            else:
                return (None, None)

            return (width, height)
        except OSError:
            pass

    return (None, None)

Очень надеюсь на вашу помощь. Заранее благодарен.