MKV files are uploaded without conversion and not playable in Telegram

[papapa228]

When feeding an MKV file to the bot, it uploads it directly via reply_video without converting the container or codecs; as a result, Telegram treats it as an unsupported format (often showing it as a downloadable document), and if it does display, video plays without sound.

The bot should automatically remux or transcode MKV (and other non‑MP4/H.264/AAC) files into an MP4 container with H.264 video and AAC audio—formats supported by Telegram’s in‑app player.