Free online RMVB to XVID converter

Some older players, televisions, and editing applications support Xvid in an AVI container but cannot open RealMedia Variable Bitrate files. Converting an RMVB file to Xvid creates a more widely supported MPEG-4 video while preserving a conventional AVI workflow.

What the RMVB format is

RMVB means RealMedia Variable Bitrate. It is a RealNetworks video container that stores video encoded at changing bitrates, allocating more data to complex scenes and less to simple ones. The format was common in internet-distributed video, especially older archives and releases, because it could produce relatively small files at dial-up and low-bandwidth resolutions.

RMVB files normally use the .rmvb extension and are associated with RealPlayer and RealProducer. You may also encounter them in older personal archives, downloaded television episodes, or software that was built around RealMedia playback. Modern applications support RMVB inconsistently because the format and some of its codecs are now uncommon.

What the Xvid format is

Xvid is an implementation of the MPEG-4 Part 2 Advanced Simple Profile video codec. It is not normally a complete container format: an “Xvid file” generally means an AVI file containing Xvid video, usually with MP3 audio. Use an output filename such as converted.avi, not converted.xvid.

Xvid remains useful for older DVD players, televisions, set-top boxes, media players, and editing software that specifically expect MPEG-4 ASP in AVI. It has broad legacy compatibility and modest hardware requirements, but H.264 and newer codecs usually provide better quality at the same bitrate. Xvid encoding cannot preserve the original RMVB compression without another lossy generation.

How to actually convert RMVB to Xvid

Using FFmpeg

FFmpeg is the most controllable desktop method. Use a build that can decode RealMedia files and includes the Xvid encoder, usually named libxvid. Check for the encoder with ffmpeg -encoders | grep libxvid on macOS or Linux. On Windows, use ffmpeg -encoders | findstr xvid.

1. Place the source file in an accessible folder and note its exact name, such as source.rmvb.
2. Run this command from that folder:
   ffmpeg -i source.rmvb -c:v libxvid -q:v 4 -c:a libmp3lame -b:a 128k -pix_fmt yuv420p converted.avi
3. Open converted.avi in the target player and check that both video and audio work.

The -q:v 4 setting uses quality-based Xvid encoding; lower values generally produce higher quality and larger files. Values around 3–5 are a practical starting range. If the target device requires a particular frame size, add, for example, -vf scale=720:-2. The -2 keeps the height even, which many MPEG-4 encoders require.

If FFmpeg reports that libxvid is unavailable, install an FFmpeg build compiled with Xvid support or use a desktop video converter that exposes an Xvid or MPEG-4 ASP codec option. Select AVI as the container, Xvid as the video codec, and MP3 or PCM-compatible audio as required by the receiving device.

Using the built-in online converter

You can convert the file on 101convert.com for free without installing software. Upload the RMVB file, choose Xvid or AVI with Xvid video when the output options are shown, start the conversion, and save the resulting AVI file. Check the service's file-size and retention limits before uploading private or copyrighted material.

Quality and compatibility limits

Conversion decodes the RMVB stream and encodes it again as Xvid, so it cannot restore detail already lost in the source. Avoid unnecessary resizing, and use a lower -q:v value or a higher bitrate if blocking and ringing are visible.

Some hardware accepts Xvid only with specific constraints: AVI container, MPEG-4 ASP profile, 4:3 or standard-definition dimensions, packed B-frames disabled, and MP3 audio at a supported sample rate. If playback fails, try a simpler command with -c:a libmp3lame -ar 44100 -ac 2 -b:a 128k and a standard size such as 640×480 or 720×576.

Variable frame rate and damaged timestamps in older RMVB files can cause audio/video drift. If that occurs, add -vsync cfr and specify a frame rate appropriate to the source, such as -r 25 or -r 29.97; changing the frame rate can duplicate or drop frames, so use it only when inspection confirms the source timing is unsuitable.