Free online RMVB to DAT converter

Legacy VCD players and some video-authoring programs expect an MPEG-1 program stream with a .dat extension rather than an RMVB file. Converting it requires decoding RealVideo and usually re-encoding it to the lower-resolution MPEG-1 video used by Video CD.

What the RMVB format is

RMVB means RealMedia Variable Bitrate. It is a container developed by RealNetworks for RealVideo and RealAudio streams, using variable bitrate allocation to reduce file size while preserving more detail in complex scenes.

RMVB files were common in RealPlayer-based downloads, older video archives, and media shared on websites and forums. RealPlayer created and played them, while FFmpeg and several other modern media tools can decode many RMVB variants without the original RealNetworks software.

What the DAT format is

In the Video category, .dat normally means the MPEG-1 program-stream file used on Video CD discs. It contains MPEG-1 video and usually MPEG-1 Layer II audio; the extension identifies the disc-oriented file convention rather than a unique codec.

DAT is useful when a VCD player, older DVD/VCD authoring application, or hardware media device specifically expects this format. A typical VCD stream uses 352×240 pixels at 29.97 fps for NTSC or 352×288 pixels at 25 fps for PAL, with approximately 1,150 kbit/s MPEG-1 video and 224 kbit/s audio. Changing an RMVB filename to .dat does not create a valid MPEG-1 DAT file.

How to actually convert RMVB to DAT

FFmpeg is the most controllable desktop option. Install a current FFmpeg build, open a terminal in the folder containing input.rmvb, and run:

ffmpeg -i input.rmvb -c:v mpeg1video -b:v 1150k -c:a mp2 -b:a 224k -ar 44100 -f mpeg output.dat

This creates an MPEG-1 system stream and gives it the DAT extension. If the source has multiple audio or video streams, select the desired ones explicitly, for example:

ffmpeg -i input.rmvb -map 0:v:0 -map 0:a:0 -c:v mpeg1video -b:v 1150k -c:a mp2 -b:a 224k -ar 44100 -f mpeg output.dat

For a VCD-compatible result, use the appropriate television standard and frame size. NTSC:

ffmpeg -i input.rmvb -vf scale=352:240,fps=30000/1001 -c:v mpeg1video -b:v 1150k -minrate 1150k -maxrate 1150k -bufsize 327680 -c:a mp2 -b:a 224k -ar 44100 -ac 2 -f mpeg output.dat

PAL requires scale=352:288,fps=25 instead. Some authoring applications require a complete VCD disc image rather than a standalone DAT file; in that case, import the encoded file into the application's Video CD authoring or equivalent menu and let it create the disc structure.

For a no-installation option, you can convert the file for free on the 101convert.com website by selecting the video conversion function, uploading the RMVB file, choosing DAT as the output, and downloading the result. Uploading is unsuitable for confidential video or very large files.

Quality, compatibility, and limitations

The conversion is normally lossy twice: RMVB is decoded from its existing compression, then the video is re-encoded as lower-bitrate MPEG-1. Increasing the DAT bitrate cannot restore detail already lost in the RMVB source.

Choose NTSC or PAL to match the intended player. Incorrect frame rates can cause stutter, while unsupported dimensions or audio parameters can make a file fail VCD authoring even when it has a .dat extension.

FFmpeg supports many RealVideo codecs, but damaged files, proprietary encryption, unusual RealAudio streams, or unsupported old codecs may produce decoding errors. Test the output with a media player and, for physical discs, test a rewritable disc or the authoring application's compliance check before making copies.