Extract Audio from VOB to OGA — Free Online Tool
Extract audio from VOB DVD files and convert it to OGA format using the Vorbis codec — stripping the MPEG-2 video and AC3 audio tracks and re-encoding the audio as an open, efficient Ogg Vorbis stream. Ideal for archiving DVD audio content in a royalty-free, broadly supported format.
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FFmpeg Command
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Estimated output:
Conversion Complete!
DownloadHow It Works
VOB files are DVD-Video containers that multiplex MPEG-2 video, AC3 (Dolby Digital) audio, subtitle streams, and sometimes multiple audio tracks into a single file. During this conversion, FFmpeg discards the video stream entirely using the -vn flag, then decodes the AC3 audio and re-encodes it as Vorbis audio wrapped in an Ogg container (.oga). Because AC3 and Vorbis use completely different codecs — AC3 being a fixed-bitrate Dolby Digital format and Vorbis being a variable-quality open codec — the audio must be fully decoded and re-encoded rather than simply copied. The output is an audio-only OGA file containing a single Vorbis stream at the quality level you specify.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool, which handles all demuxing, decoding, encoding, and muxing for this VOB-to-OGA conversion entirely within your browser via WebAssembly. |
-i input.vob
|
Specifies the input VOB file. FFmpeg reads and demultiplexes the VOB container, identifying the multiplexed MPEG-2 video stream, AC3 audio stream, and any subtitle or additional audio tracks present in the DVD Video Object. |
-vn
|
Disables video output entirely, instructing FFmpeg to ignore the MPEG-2 video stream from the VOB. Without this flag, FFmpeg would attempt to encode or include video in the output, which OGA — being an audio-only container — cannot hold. |
-c:a libvorbis
|
Selects the libvorbis encoder to re-encode the audio. Since the VOB's AC3 audio and Vorbis use entirely different codecs, the AC3 must be decoded and re-encoded as Vorbis — a stream copy is not possible here. |
-q:a 4
|
Sets the Vorbis variable bitrate quality level to 4 on a scale of 0–10, targeting approximately 128 kbps. This is a balanced default suitable for most DVD audio content including dialogue and music; increase to 6–8 for concert or high-fidelity music DVDs. |
output.oga
|
Defines the output file using the .oga extension, which signals an audio-only Ogg container. FFmpeg wraps the encoded Vorbis stream into this container, producing a self-contained audio file with no video or subtitle data. |
Common Use Cases
- Ripping the audio commentary track from a DVD movie VOB file to listen to on a device that doesn't support AC3 or DVD playback
- Extracting a concert or music DVD's audio into an open-format Vorbis file for archival or playback in Ogg-compatible media players
- Converting DVD-sourced language learning audio (e.g., from educational DVDs) into portable OGA files for use in open-source language apps
- Pulling the soundtrack from a home-recorded DVD (e.g., a school play or family event) into a lightweight audio file for sharing without the large video
- Archiving audio from aging DVD discs into a modern, royalty-free Vorbis format before the physical media degrades
- Extracting dialogue or narration from a training or documentary DVD to use as a standalone audio resource
Frequently Asked Questions
Yes, some generation loss occurs because both AC3 and Vorbis are lossy codecs, and this conversion requires a full decode-and-re-encode cycle rather than a stream copy. The AC3 audio in your VOB is first decoded to raw PCM, then re-encoded as Vorbis. At the default quality setting (-q:a 4), the output Vorbis audio is generally transparent to most listeners, but it is a second-generation lossy encode. If your VOB source has a lossless audio track, the loss is minimal at higher quality settings.
By default, FFmpeg selects the first audio stream it finds in the VOB file. VOB files from commercial DVDs often contain multiple AC3 audio tracks for different languages. If you need a specific track, you can modify the command to add -map 0:a:1 (for the second audio track) or -map 0:a:2 (for the third), replacing the index number with the track you want. The OGA format only supports a single audio track per file, so you can only extract one at a time.
Both .ogg and .oga use the Ogg container format, but .oga is the formally designated extension for audio-only Ogg files, as standardized by the Xiph.Org Foundation. Using .oga signals clearly that the file contains only audio (in this case, Vorbis) with no video stream, which helps media players and tools handle the file correctly. The .ogg extension is more commonly used in practice, but .oga is technically more precise for audio-only content.
The -q:a 4 flag controls Vorbis quality using a variable bitrate scale from 0 (lowest quality, smallest file) to 10 (highest quality, largest file). Quality 4 targets roughly 128 kbps and is a solid default for most content. For higher-fidelity music or concert DVD audio, try -q:a 6 or -q:a 8, which targets around 192–256 kbps. For voice-only content like commentary or narration, -q:a 2 or -q:a 3 is often sufficient and produces significantly smaller files.
Yes. On Linux or macOS, you can use a shell loop: for f in *.vob; do ffmpeg -i "$f" -vn -c:a libvorbis -q:a 4 "${f%.vob}.oga"; done. On Windows Command Prompt, use: for %f in (*.vob) do ffmpeg -i "%f" -vn -c:a libvorbis -q:a 4 "%~nf.oga". This is especially useful for DVD rips that are split across multiple numbered VOB files (VTS_01_1.vob, VTS_01_2.vob, etc.).
Subtitles are not preserved — OGA does not support subtitle streams, and the conversion strips all non-audio data. Chapter metadata from the VOB is also not carried over by default in this command. OGA/Ogg does support chapter markers through a comment header mechanism, but FFmpeg does not automatically map VOB chapter data into Ogg chapters during this extraction. Basic metadata tags like title and artist may be passed through if present in the VOB source.
Technical Notes
VOB files store audio as AC3 (Dolby Digital) at fixed bitrates typically ranging from 192 kbps to 448 kbps for stereo and 5.1 surround content. When converting to OGA/Vorbis, FFmpeg fully decodes the AC3 stream to PCM and then re-encodes with the libvorbis encoder. Importantly, if the source VOB contains 5.1 surround AC3 audio, libvorbis will encode the full multichannel audio into the Vorbis stream — Vorbis supports up to 255 channels. However, Vorbis channel mapping for 5.1 uses a different channel order than AC3, which FFmpeg handles automatically. The OGA container supports chapters but not subtitle streams, so any DVD subtitle or menu data in the VOB is silently discarded. The -f vob input flag is sometimes needed when FFmpeg struggles to detect the VOB format automatically, particularly with truncated or partially demuxed files. File sizes will generally be smaller than the audio portion of the original VOB due to Vorbis's more modern and efficient compression compared to AC3 at equivalent perceived quality levels.