RealMedia Variable Bitrate (RMVB) is a variable bitrate extension of the RealMedia multimedia container format developed by RealNetworks.

    As opposed to the more common RealMedia container, which holds streaming media encoded at a constant bit rate, RMVB is typically used for multimedia content stored locally. Files using this format have the file extension ".rmvb".

    RealMedia uses compression similar to MPEG-4 Part 10 codecs, such as x264.

    RMVB files are extremely popular for distributing Asian content, especially anime and Chinese television episodes.[citation needed] For this reason, they have become noticeably present (though not entirely popular) on file sharing platforms such as BitTorrent, eDonkey and Gnutella.[citation needed]

    Limited support is available on some media players, generally on the Windows platform, including the proprietary RealPlayer 10 and the open-sourced Media Player Classic, using an appropriate DirectShow filter or Real Alternative. MPlayer and some other programs such as totem are able to play RMVB files in Linux/UNIX-based x86 machines through the use of WIN32 DLLs or native closed-source libraries