Try all chunks when detecting file mimetype

boards/models/attachment/viewers.py

@@ -30,6 +30,7 b' FILE_TYPES_AUDIO = ('
     'audio/mp3',
     'audio/opus',
     'audio/x-flac',
+    'audio/mpeg',
 )
 FILE_TYPES_IMAGE = (
     'image/jpeg',

boards/utils.py

@@ -135,7 +135,7 b' def get_upload_filename(model_instance, '
 
 
 def get_file_mimetype(file) -> str:
-    file_type = magic.from_buffer(file.chunks().__next__(), mime=True)
+    file_type = magic.from_file(settings.MEDIA_ROOT + file.name, mime=True)
     if file_type is None:
         file_type = 'application/octet-stream'
     elif type(file_type) == bytes: