MyMediaTools

Convert WebM to VOB — Free Online Tool

Convert WebM files to VOB format, transcoding VP9 video to MPEG-2 and Opus audio to AC3 — the codec pair required by the DVD-Video specification. This is the go-to tool for taking modern web video and preparing it for DVD authoring workflows.

FFmpeg Command

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Estimated output:

Conversion Complete!

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How It Works

WebM and VOB are fundamentally different containers built for opposite ends of the video ecosystem. WebM uses VP9 video compression and Opus audio, neither of which is compatible with the DVD-Video specification. During conversion, the VP9 video stream is fully re-encoded to MPEG-2 — the mandatory codec for DVD-Video — which is a computationally intensive process that also reduces compression efficiency, meaning VOB files will typically be significantly larger than their WebM source. The Opus audio track is simultaneously re-encoded to AC3 (Dolby Digital), the standard audio codec used on DVDs. The output is wrapped in the VOB container with the -f vob flag, which structures the multiplexed streams in a way compatible with DVD authoring tools like DVDStyling or ImgBurn. Any alpha channel transparency present in the WebM is discarded, as MPEG-2 has no transparency support. Subtitle streams can be carried over if present, but chapter metadata is not preserved since VOB does not support chapter markers at the container level.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg program. When run in this browser tool, the equivalent FFmpeg.wasm WebAssembly build is used, which processes your file entirely locally without any server upload.
-i input.webm Specifies the input WebM file. FFmpeg reads the VP9 video stream and Opus (or Vorbis) audio stream from this container in preparation for transcoding to DVD-compatible codecs.
-c:v mpeg2video Instructs FFmpeg to re-encode the VP9 video stream to MPEG-2, the video codec mandated by the DVD-Video specification and the only video format VOB players universally expect.
-c:a ac3 Instructs FFmpeg to re-encode the Opus audio stream to AC3 (Dolby Digital), the primary audio codec used on DVD-Video discs and supported by virtually all standalone DVD players.
-q:v 4 Sets the MPEG-2 video quality using a fixed quantizer scale, where 1 is the highest quality and 31 is the lowest. A value of 4 targets near-high quality suitable for DVD authoring while keeping file sizes manageable.
-b:a 192k Sets the AC3 audio bitrate to 192 kilobits per second, a standard DVD audio bitrate that provides good stereo fidelity. DVD-Video commonly uses 192k for stereo and up to 448k for surround sound tracks.
-f vob Explicitly forces the VOB muxer, ensuring the MPEG-2 video and AC3 audio are multiplexed in the correct structure for the DVD-Video container format rather than relying on the output filename extension alone.
output.vob The name of the resulting VOB file containing the transcoded MPEG-2 video and AC3 audio, ready to be imported into DVD authoring software as part of a VIDEO_TS disc structure.

Common Use Cases

  • Preparing web-sourced or screen-recorded WebM video for inclusion in a DVD authoring project using tools like DVDStyler or ImgBurn
  • Archiving online video content to physical DVD media for playback on standalone DVD players that cannot read VP9 or WebM
  • Converting a WebM-based presentation or tutorial recording into a VOB file for use in a legacy DVD-based training kit
  • Taking a WebM video exported from a browser-based editor and converting it to the MPEG-2/AC3 format required by professional DVD mastering software
  • Repurposing HTML5 web video content for distribution on DVD at events or conferences where internet access cannot be guaranteed
  • Converting WebM recordings from video conferencing tools into a format compatible with older video editing suites that support MPEG-2 but not VP9

Frequently Asked Questions

VP9, the codec used in WebM, is a modern compression algorithm designed to deliver high quality at low bitrates — it is significantly more efficient than MPEG-2. When converting to VOB, the video must be re-encoded to MPEG-2, which achieves far less compression for equivalent visual quality. A WebM that is 200MB could easily become 600MB or more as a VOB. This size increase is an unavoidable consequence of the codec difference, not a flaw in the conversion process.
Not typically. A raw VOB file contains the correct MPEG-2 video and AC3 audio streams, but a standard DVD player expects a full DVD-Video disc structure — including IFO and BUP index files alongside the VOB files in a VIDEO_TS folder. You will need DVD authoring software such as DVDStyler, ImgBurn, or Adobe Encore to import the VOB and build a proper disc structure before burning or creating an ISO image.
Yes, this conversion is lossy at every stage. The VP9 video is decoded and re-encoded to MPEG-2, which introduces generation loss — artifacts can appear, particularly in scenes with fine detail or fast motion, because MPEG-2 is less efficient than VP9. Similarly, the Opus audio is decoded and re-encoded to AC3. Using a lower -q:v value (closer to 1) in the FFmpeg command will maximize MPEG-2 quality, while higher values (toward 31) will reduce quality and file size.
The alpha channel is permanently discarded. WebM with VP9 supports transparency, but MPEG-2 — the video codec used in VOB — has no concept of an alpha channel. Any transparent regions in your WebM source will be composited against a black background in the output VOB. If you need to preserve transparency for compositing work, VOB is not the appropriate target format.
Adjust the -q:v value to control MPEG-2 video quality. The scale runs from 1 (highest quality, largest file) to 31 (lowest quality, smallest file), with the default set to 4. For DVD authoring where visual quality is a priority, values between 1 and 6 are recommended. For example, replace '-q:v 4' with '-q:v 2' for near-maximum quality. You can also increase audio quality by changing '-b:a 192k' to a higher bitrate such as '-b:a 384k' for more faithful AC3 audio.
Yes. On Linux or macOS, you can use a shell loop: 'for f in *.webm; do ffmpeg -i "$f" -c:v mpeg2video -c:a ac3 -q:v 4 -b:a 192k -f vob "${f%.webm}.vob"; done'. On Windows Command Prompt, use: 'for %f in (*.webm) do ffmpeg -i "%f" -c:v mpeg2video -c:a ac3 -q:v 4 -b:a 192k -f vob "%~nf.vob"'. The browser-based tool on this page processes one file at a time, so the FFmpeg command is especially valuable for batch workflows involving many files.

Technical Notes

The VOB format is rigidly defined by the DVD-Video specification, which mandates MPEG-2 video at specific resolutions (typically 720x480 for NTSC or 720x576 for PAL) and AC3, MPEG-1 Layer 2, or LPCM audio. This converter uses MPEG-2 and AC3 as defaults, which is the most widely compatible combination. If your WebM source is at a non-standard DVD resolution, the MPEG-2 encoder will encode at the source resolution, which may cause compatibility issues with strict DVD players — consider adding explicit resolution flags like '-s 720x480' for NTSC targets when running the command locally. The -f vob flag explicitly tells FFmpeg to use the VOB muxer rather than guessing from the file extension, which is important for correct stream multiplexing. VOB does not support chapter metadata, so any chapter markers in the WebM source are silently dropped. Multiple audio tracks from a WebM source can be carried forward into the VOB, as the format does support multiple audio streams, but you must specify stream mapping explicitly using -map flags in the FFmpeg command if you want to preserve more than the default audio track. WebM's HDR metadata (if present with VP9 HDR content) will not be preserved, as MPEG-2 has no HDR signaling capability.

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