RMVB to MKV Converter

How to Convert RMVB to MKV Online

1. Upload Your RMVB File: Drag and drop or click "Add Files" to select .rmvb files — old RealMedia Variable Bitrate downloads, fan-sub releases, or RealPlayer-era video archives. Batch is supported, so a folder of .rmvb files moves over to MKV in a single pass.
2. Pick a Video Codec and Quality: Default is H.264 — the universal codec that plays in MKV on every modern player and decodes in hardware on every chip since 2010. Choose H.265 / HEVC for roughly 40% smaller files at the same visual quality, AV1 for the smallest size on 2022+ players, VP9 for royalty-free encoding, or MPEG-4 / XVID / DIVX for a DivX-style archive. Set a quality preset (Highest, Very High, High, Medium, Low, Very Low, Lowest), target an exact file size in MB, target a percentage of the source, or fine-tune with CRF (18 = visually lossless, 23 = default, 28 = smaller).
3. Pick an Audio Codec and Resize / Trim (Optional): Audio defaults to AAC; MKV will also carry AC-3, E-AC-3, DTS, FLAC, Opus, Vorbis, MP3, MP2, PCM (plus speech codecs and lossless options) — RealAudio Cook from the source RMVB is decoded once and re-encoded into the chosen track. Most legacy RMVB releases ran at 240p, 360p, 480p, or 640x480 for early-broadband bandwidth, so a resolution preset (240p / 360p / 480p / 720p / 1080p), a custom width × height, or a percentage scale all work; leave at original to preserve the source frame. Trim a section using start time and duration in HH:MM:SS.sss format if only part of the RMVB belongs in the MKV.
4. Convert and Download: Click Convert. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours — no sign-up, no watermark, never shared.

Why Convert RMVB to MKV?

RMVB (RealMedia Variable Bitrate) is RealNetworks' variable-bitrate streaming container that became the dominant fan-sub and TV-rip distribution format on Chinese, Taiwanese, Korean, and Southeast-Asian download sites from roughly 2003 to 2010. Inside a typical .rmvb file you'll find RealVideo RV30 / RV40 video and RealAudio Cook audio. RealPlayer's last consumer release shipped in the mid-2010s and the format is no longer supported on modern phones, smart TVs, browsers, or NLE software. MKV (Matroska) is the open-source container of choice for re-housing that content — it carries any codec, any number of audio and subtitle tracks, chapters, and metadata, and plays in VLC, mpv, Kodi, Plex, Jellyfin, and most modern media servers. Converting RMVB to MKV is the standard archival path for legacy RealMedia collections:

• Asian-archive modernisation — Personal archives of Chinese, Korean, Japanese, and Taiwanese TV episodes, dramas, and films that were distributed as .rmvb from 2003-2010 are largely unplayable on iPhone, Android, or smart TVs today. Re-containerised into MKV with H.264 or H.265, the same library plays on Plex, Jellyfin, Kodi, and every modern client.
• Multiple audio and subtitle tracks — Many RMVB releases shipped with hard-burned subtitles. Converting to MKV lets you re-encode the video at modern quality and then add separate .srt or .ass subtitle tracks with MKVToolNix or a video editor, plus optional dual-language audio tracks — none of which RMVB supports natively.
• Plex / Jellyfin / Kodi media servers — Plex and Jellyfin do not transcode RMVB on most clients (RealVideo decoders aren't bundled in their hardware-acceleration stacks), so an .rmvb in a Plex library typically refuses to play on Apple TV, Roku, or Fire TV. MKV with H.264 or H.265 direct-plays on every Plex client.
• Editing in DaVinci Resolve, Premiere, Final Cut — None of the major NLEs import .rmvb. Re-encoding to MKV with H.264 + AAC produces a file that drops straight onto a timeline in DaVinci Resolve, Premiere Pro, Final Cut Pro, Kdenlive, or Shotcut.
• Hardware playback on modern devices — iPhone, Android, Roku, Apple TV, Fire TV, and every smart TV decode H.264 / H.265 in hardware but have no decoder for RealVideo at all. MKV with H.264 plays everywhere; H.265 plays on Apple devices since iOS 11 (2017), Android 9+, and 2017+ smart TVs.
• Long-term archival — RealVideo and RealAudio decoders are only maintained today inside FFmpeg / libavcodec. Re-encoding to a modern codec inside MKV — itself an open container with active development — gives the content a dramatically longer survival window than leaving it as .rmvb.

For other legacy-RealMedia targets, see RMVB to MP4 (smaller, more universal container), RMVB to AVI, or the reverse MKV to RMVB.

RMVB vs MKV — Format Comparison

Codec Quick Guide for MKV Output

Frequently Asked Questions

Will the MKV file be smaller than the original RMVB?

It depends on the codec choice. RMVB used variable-bitrate RV30 / RV40 at low bitrates (200-700 kbps was typical for 480p TV-rip releases), so a fresh H.264 encode at the source resolution is often a similar size or slightly larger. Choosing H.265 at default CRF usually produces an MKV around 10-30% smaller than the source RMVB; AV1 trims that further. Re-encoding cannot recover detail the RMVB lost during its original variable-bitrate compression — it just re-houses it in a modern, playable container.

Should I pick H.264 or H.265 for the output?

H.264 is the safe default. It direct-plays on every Plex / Jellyfin / Kodi client, decodes in hardware on every device, and works on retro hardware down to first-generation iPads. H.265 / HEVC produces files roughly 40% smaller at the same visual quality and is the right pick when the target devices are Apple devices from 2017 onward, Android 9+, or smart TVs from 2017+. For a one-time archival re-encode of an old RMVB collection, H.264 with the default CRF and the source resolution kept is almost always the right pick.

Will subtitles transfer from the RMVB?

Many RMVB releases — especially Chinese and Korean fan-subs from the 2000s — have hard-burned subtitles painted directly into the video frame. Those will appear in the MKV output exactly as they did in the source because the converter re-encodes the video pixels. Soft subtitle tracks were rare in .rmvb. After converting to MKV, you can add separate .srt or .ass subtitle tracks (and additional audio tracks) using MKVToolNix without re-encoding the video — that's one of MKV's biggest advantages over MP4.

What audio codec ends up in the MKV file?

Default is AAC for the broadest player compatibility; MKV will also carry AC-3 / E-AC-3 / DTS (good when feeding a Plex library to a home-theatre receiver), FLAC (lossless), Opus (most efficient), Vorbis, MP3, MP2, or PCM. The RealAudio Cook track inside the source RMVB is decoded once and re-encoded into the chosen format — RealAudio cannot be carried in MKV directly. RA Cook was already a low-bitrate codec (32-64 kbps was typical), so the re-encoded AAC track will sound the same as the source rather than worse.

Can VLC, Plex, Kodi, and Jellyfin play the resulting MKV?

Yes — all four play MKV with H.264 or H.265 video out of the box, and Plex / Jellyfin direct-play to Apple TV, Roku, Fire TV, and modern smart TVs without server-side transcoding. That's the whole point of the conversion: an .rmvb in a Plex library typically refuses to play on most clients because RealVideo isn't part of any hardware-decoding stack, while H.264 inside MKV plays everywhere.

Can I batch convert a whole folder of RMVB files?

Yes — drop in as many .rmvb files as needed and they convert in parallel withon our servers. Files download individually or as a single ZIP. This is the typical workflow when modernising an entire Asian-archive collection (whole TV series, multi-disc film sets) into a Plex / Jellyfin library.

Is there a file size limit?

Conversion runs on our servers, so the practical limit is upload size and connection speed rather than a fixed cap. Most legacy RMVB files are modest in size (a 45-minute TV-rip episode at 480p was typically 175-400 MB), so memory is rarely a constraint. Competitors like FreeConvert cap free conversions at 1 GB; xconvert has no fixed cap, no sign-up, no watermark, and no quantity limit on batch jobs.

Will the conversion be lossless?

No — RealVideo and RealAudio in the source .rmvb cannot be copied into MKV directly because Matroska doesn't carry those streams as native tracks the way it carries H.264 or AAC. The video is decoded from RV30 / RV40 and re-encoded into the chosen MKV codec. Use Constant Quality (CRF 18) or the Highest quality preset for a visually-lossless re-encode that keeps every detail the source RMVB had.

What's the difference between RMVB and RM?

.rm files use a fixed (constant) bitrate; .rmvb files use a variable bitrate — the "VB" in the extension — giving more bits to complex scenes and fewer to static ones. RMVB became the preferred RealMedia variant for downloaded video because it produced smaller files at comparable visual quality. For constant-bitrate RealMedia source, use the RM to MP4 converter instead.