Free online WEBM to DAT converter

A VCD player, legacy media application, or authoring workflow may require a video DAT file instead of a WEBM file. The conversion changes the modern WEBM stream into the MPEG-1 video format used inside Video CD files; changing the filename extension alone does not perform that conversion.

What the WEBM format is

WEBM is a multimedia container based on Matroska. It commonly contains VP8, VP9, or AV1 video with Vorbis or Opus audio and is widely used for browser playback, web downloads, screen recordings, and HTML5 video.

Browsers, web applications, OBS Studio, FFmpeg, and other recording or publishing tools can create WEBM files. WEBM is optimized for web delivery, but many older DVD/VCD players and video applications cannot decode its codecs.

What the DAT format is

In the Video category, DAT usually means the MPEG-1 program-stream file used by a Video CD (VCD). A VCD DAT normally contains MPEG-1 video at 352×288 pixels and 25 frames per second for PAL, or 352×240 pixels and approximately 29.97 frames per second for NTSC, with MPEG-1 Layer II audio at 44.1 kHz.

DAT is useful when creating or preserving a VCD because older standalone players recognize the VCD structure and its MPEG-1 stream. It is not a universal video container specification, so a program that asks for “DAT” may expect either a VCD-compatible MPEG stream or a DAT file extracted from a complete VCD image.

How to actually convert WEBM to DAT

FFmpeg is the most controllable desktop option. Install FFmpeg, place the source file in a working folder, and use a VCD target preset. For a PAL video, run:

ffmpeg -i input.webm -target pal-vcd -f mpeg output.dat

For an NTSC video, run:

ffmpeg -i input.webm -target ntsc-vcd -f mpeg output.dat

The presets select MPEG-1 video, VCD-compatible dimensions and frame rate, 44.1 kHz audio, and the typical VCD bitrate. Replace input.webm with the actual filename. The -f mpeg option forces an MPEG program stream even though .dat is not a reliably recognized extension.

If the receiving program only requires an MPEG-1 file with a DAT extension, these commands may be sufficient. For a playable VCD, create the disc structure instead of treating the output as an ordinary renamed video. Use a VCD authoring tool such as VCDImager to generate the disc image, then burn that image with disc-authoring software. A typical VCD authoring workflow starts with a compliant MPEG-1 file produced as:

ffmpeg -i input.webm -target pal-vcd output.mpg

The authoring software places the encoded stream in the appropriate VCD directory and generates the DAT file and control files required by VCD players. A standalone output.dat file may not work if the destination expects the complete VCD layout.

For a one-off conversion without installing software, the free converter on 101convert.com can process the file online. Upload the WEBM, choose DAT as the output, and download the result; the service may choose a generic MPEG-compatible DAT stream rather than a disc-ready VCD image.

Quality, compatibility, and limitations

WEBM cannot normally be stream-copied into DAT because VP8, VP9, or AV1 video must be decoded and re-encoded as MPEG-1. Re-encoding causes quality loss, and converting a high-resolution WEBM to VCD resolution removes detail permanently.

VCD video uses a low fixed bitrate, so fast motion may show block artifacts. Upscaling a small WEBM to the VCD frame size does not add detail. Choose PAL or NTSC to match the intended player; the wrong standard can produce playback failure or incorrect timing.

A VCD holds roughly 74 or 80 minutes of video using the standard disc modes. If the source is longer, split it into compliant tracks or use a different disc format. Some modern players accept an MPEG-1 DAT stream directly, while others require a correctly authored VCD image and directory structure.