Remove slow python converters and use asyncio subprocess

example-config.yaml

@@ -163,16 +163,22 @@ bridge:
     image_as_file_size: 10
     # Maximum size of Telegram documents in megabytes to bridge.
     max_document_size: 100
-    # Format, animated sticker convert to.
-    # Supported values:
-    # png - converts to png (fastest and preferred),
-    # gif - converts to gif animation, requires PIL, slow, sometimes loses transparency,
-    # gifc - uses same utility as png, faster but without transparency at all
-    # mp4 - video in mp4 container (ffmpeg binary and takes a lot of time, but less than gif)
-    animated_sticker_target_type: gif
     # Whether or not created rooms should have federation enabled.
     # If false, created portal rooms will never be federated.
     federate_rooms: true
+    # Settings for converting animated stickers.
+    animated_sticker:
+        # Format to which animated stickers should be converted.
+        # disable - No conversion, send as-is (gzipped lottie)
+        # png - converts to non-animated png (fastest),
+        # gif - converts to animated gif, but loses transparency
+        target: gif
+        # Arguments for converter. All converters take width and height.
+        # GIF converter takes background as a hex color.
+        args:
+            width: 256
+            height: 256
+            background: "ffffff"
 
     # Whether to bridge Telegram bot messages as m.notices or m.texts.
     bot_messages_as_notices: true