Extract Audio from VOB to WEBA — Free Online Tool
Extract audio from VOB DVD files and convert it to WEBA format, transcoding the AC3 (Dolby Digital) surround audio into Opus-encoded WebM audio optimized for web streaming. Ideal for pulling soundtrack or dialogue audio from DVD rips into a lightweight, browser-compatible format.
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FFmpeg Command
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Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
VOB files store MPEG-2 video alongside AC3 (Dolby Digital) audio — the standard encoding used on DVD-Video discs. During this conversion, FFmpeg discards the MPEG-2 video stream entirely and transcodes the AC3 audio into Opus audio wrapped in a WebM container (.weba). Opus is a modern, royalty-free lossy codec that typically delivers better perceptual quality than AC3 at equivalent or lower bitrates. Because AC3 and Opus use completely different encoding schemes, the audio must be fully decoded and re-encoded — it cannot be stream-copied. If the VOB file contains multiple audio tracks (e.g., different languages or commentary tracks), only the default track is extracted unless you specify otherwise.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool. In the browser-based version of this tool, FFmpeg runs via WebAssembly (FFmpeg.wasm) entirely on your local machine — no data is sent to a server. |
-i input.vob
|
Specifies the input VOB file. FFmpeg will parse the MPEG-2 program stream structure of the VOB, identifying all contained streams including MPEG-2 video, AC3 audio tracks, and any subtitle streams. |
-vn
|
Disables video output, telling FFmpeg to ignore the MPEG-2 video stream from the VOB entirely. This is essential since WEBA is an audio-only container and cannot hold video data. |
-c:a libopus
|
Transcodes the audio using the Opus encoder. Since the source AC3 audio from the DVD cannot be stream-copied into a WebM container, it is fully decoded and re-encoded as Opus — a modern, royalty-free codec well-suited for web audio delivery. |
-b:a 128k
|
Sets the Opus audio output bitrate to 128 kilobits per second. Opus at 128k generally delivers transparent or near-transparent quality for most content, and is significantly more efficient than the AC3 source at equivalent bitrates. |
-vn
|
A second '-vn' flag applied at the output stage, reinforcing that no video stream should be written to the WEBA file. This guards against edge cases where FFmpeg might attempt to include video data in the output container. |
output.weba
|
The output filename with the .weba extension. FFmpeg recognizes this extension as an audio-only WebM container and configures the muxer accordingly, producing a file natively supported by web browsers for use in HTML5 audio elements or web applications. |
Common Use Cases
- Extract the Dolby Digital soundtrack from a DVD rip of a concert or live performance to share as web-compatible audio
- Pull dialogue or narration audio from a DVD training or educational video to embed as a WEBA audio element on a website
- Convert DVD commentary tracks from VOB to WEBA for archiving or web playback without needing a video player
- Extract the audio from a DVD film rip to create a lightweight preview clip for embedding in a browser-based media player
- Convert VOB audio to Opus/WEBA for use in a Progressive Web App or web game that requires WebM-compatible audio assets
- Strip the AC3 audio from a DVD VOB file and re-encode it in Opus for significantly reduced file size when video is not needed
Frequently Asked Questions
Yes, some quality loss occurs because this is a lossy-to-lossy transcode — the AC3 audio from the DVD is decoded to raw PCM and then re-encoded as Opus. However, Opus is widely considered more efficient than AC3, so at the default 128k bitrate you will often get comparable or better perceptual quality than the original AC3 stream, which on DVDs typically runs at 192k–448k. For critical listening, you can increase the output bitrate up to 320k to minimize the quality gap.
Opus fully supports multi-channel audio, so the AC3 5.1 surround mix from the VOB file can be preserved in the WEBA output. FFmpeg will decode the AC3 surround channels and re-encode them as multi-channel Opus. However, browser playback support for multi-channel Opus in WEBA containers varies, so if you need stereo-only output for web use, you can add '-ac 2' to the command to downmix to stereo.
Yes. FFmpeg selects the first (default) audio track automatically. To extract a specific track, add '-map 0:a:1' (for the second audio track) or '-map 0:a:2' (for the third) to the command before the output filename. You can identify available audio streams and their language tags by running 'ffmpeg -i input.vob' and inspecting the stream list.
Replace the '-b:a 128k' value with your desired bitrate. Supported values include 64k, 96k, 128k, 192k, 256k, and 320k. For example, use '-b:a 64k' to create a very small file for voice-only content, or '-b:a 256k' if you are extracting music audio and want to preserve more detail. Opus is highly efficient at low bitrates, so 96k is often sufficient for speech-heavy DVD content.
WEBA files with Opus audio have excellent support in Chrome, Firefox, and Edge, but Safari only added Opus support in more recent versions (Safari 16.4+) and some older iOS devices may not support it. If broad compatibility is your priority, consider converting to MP3 or AAC instead. For modern web apps and PWAs targeting Chromium-based browsers, WEBA/Opus is an excellent choice due to its small file size and high quality.
The '-vn' flag in the command appears once as an input-side option and once is actually a special output flag for WEBA that ensures no video stream is written to the output container. In practice, having it specified before the output reinforces that the video stream is dropped. The WEBA (.weba) format is an audio-only WebM container, so including '-vn' is essential to prevent FFmpeg from attempting to mux the MPEG-2 video stream into a container that cannot hold it.
Technical Notes
VOB files from DVD-Video discs commonly encode audio as AC3 (Dolby Digital) at bitrates between 192k and 448k, and may carry multiple audio streams for different languages or director commentaries. The WEBA container is a strict audio-only subset of WebM and supports only Opus (libopus) or Vorbis (libvorbis) audio — this means the AC3 audio must be fully transcoded, not stream-copied, which takes more processing time than a simple remux. The default codec chosen here is libopus, which offers superior compression efficiency over Vorbis, particularly at lower bitrates. Note that WEBA does not support subtitle streams, chapter markers, or multiple audio tracks, so any embedded DVD subtitles or secondary language tracks in the VOB will be silently discarded unless you run separate extractions. Metadata from the VOB file (such as track titles or language tags) may not be preserved in the WEBA output due to limited metadata support in the WebM specification compared to DVD's IFO-based metadata system.