yt_dlp/compat/imghdr.py

   1 def what(file=None, h=None):
   2     """Detect format of image (Currently supports jpeg, png, webp, gif only)
   3     Ref: https://github.com/python/cpython/blob/3.11/Lib/imghdr.py
   4     Ref: https://www.w3.org/Graphics/JPEG/itu-t81.pdf
   5     """
   6     if h is None:
   7         with open(file, 'rb') as f:
   8             h = f.read(12)
   9
  10     if h.startswith(b'RIFF') and h.startswith(b'WEBP', 8):
  11         return 'webp'
  12
  13     if h.startswith(b'\x89PNG'):
  14         return 'png'
  15
  16     if h.startswith(b'\xFF\xD8\xFF'):
  17         return 'jpeg'
  18
  19     if h.startswith(b'GIF'):
  20         return 'gif'
  21
  22     return None