rm
What is a .rm file?
application/vnd.rn-realmedia
RM is the RealMedia container developed for early streaming audio and video. A file consists of typed objects for the file header, properties, media streams, content metadata, packet data, and an optional index; the contained RealAudio or RealVideo codecs are separate from the container and are rarely browser-playable today.
How to use a .rm file
Use a compact example .rm file to test container signature and object-length parsing, stream and duration metadata, truncated-object handling, and download-only fallback without claiming native browser playback.