Convert VOB to OGA — Free Online Tool
Extract and convert the AC3 audio from a DVD VOB file into an OGA container using the Vorbis codec. This tool strips the MPEG-2 video and remuxes only the audio stream, making it ideal for archiving DVD dialogue, music, or commentary tracks in an open, widely-supported format.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your VOB file here
or click to browse
Free — no uploads, no signups. Your files never leave your browser.
Settings
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 are MPEG-2 program streams that bundle together video, AC3 (Dolby Digital) audio, subtitles, and sometimes multiple audio tracks into a single container used by DVD-Video discs. During this conversion, FFmpeg discards the MPEG-2 video stream entirely and transcodes the AC3 audio into Vorbis, an open lossy audio codec, which is then written into an OGA container — an audio-only variant of the Ogg format. Because AC3 and Vorbis use different compression algorithms and bitrate structures, a full audio decode-and-reencode takes place rather than a simple stream copy. The result is a significantly smaller file containing only the audio, encoded with Vorbis's variable-quality system at quality level 4 by default (roughly equivalent to 128–160 kbps).
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool, the open-source multimedia processing engine that handles demuxing the DVD VOB program stream, decoding AC3 audio, and encoding the output Vorbis audio into an OGA container. |
-i input.vob
|
Specifies the input VOB file — a DVD Video Object containing multiplexed MPEG-2 video, AC3 audio, and potentially subtitle and navigation data. FFmpeg will demux all streams but only the audio will be passed forward in this command. |
-c:a libvorbis
|
Sets the audio encoder to libvorbis, which transcodes the decoded AC3 audio from the VOB into Vorbis format — an open, patent-free lossy codec that is the native audio codec for OGA containers. |
-q:a 4
|
Sets the Vorbis variable bitrate quality level to 4 on a 0–10 scale, targeting approximately 128–160 kbps output audio. This provides a good balance between file size and perceived audio quality for typical DVD dialogue and music content. |
output.oga
|
Defines the output filename and triggers FFmpeg to write an OGA container — an audio-only Ogg file. The MPEG-2 video stream from the VOB is automatically excluded because OGA has no video codec support. |
Common Use Cases
- Extracting the musical score or soundtrack from a DVD movie VOB file to listen to offline or archive separately as an audio file
- Pulling dialogue or commentary audio from a DVD special features VOB to create transcripts or accessibility resources
- Converting a DVD concert or live performance VOB to OGA so it can be played in open-source media players like VLC or Audacious without needing the full video file
- Archiving the audio portion of home-recorded DVD backups in a compact, open-format file that doesn't depend on proprietary codecs
- Extracting a specific language audio track from a multi-language DVD VOB for language learning or translation work
- Preparing DVD audio content for use in open-source video editing projects where Vorbis/OGA is the preferred audio format
Frequently Asked Questions
Yes, some quality loss occurs because this conversion is lossy-to-lossy: the AC3 audio in a VOB is first decoded to raw PCM, then re-encoded into Vorbis. DVD AC3 tracks are typically 192–448 kbps, while the default Vorbis quality level 4 targets roughly 128–160 kbps. For most listeners the difference is not perceptible in speech or standard music, but audiophiles working with high-bitrate DVD audio may want to raise the quality level to 7 or higher in the FFmpeg command.
No — OGA is a single-stream audio container and does not support multiple audio tracks. If your VOB contains multiple language or commentary tracks, FFmpeg will select the first audio stream by default. To extract a specific track, you would need to add a stream selector like '-map 0:a:1' to target the second audio stream, and run a separate conversion for each track you want to preserve.
Subtitles are dropped entirely during this conversion. VOB files store DVD subtitles as bitmap-based subtitle streams (DVD sub format), and OGA has no support for subtitle data of any kind. If preserving subtitles alongside audio is important, you would need to choose a different output format such as MKV that supports both audio and subtitle streams.
Adjust the '-q:a' value in the command to control Vorbis quality. The scale runs from 0 (lowest, ~64 kbps) to 10 (highest, ~500 kbps), with 4 being the default (roughly 128–160 kbps). For example, changing the command to 'ffmpeg -i input.vob -c:a libvorbis -q:a 7 output.oga' will produce noticeably higher fidelity audio at the cost of a larger file size, which is useful when the source DVD has a high-bitrate AC3 surround track.
Yes — OGA supports FLAC as an alternative codec, which would give you lossless audio extracted from the DVD. Replace '-c:a libvorbis -q:a 4' with '-c:a flac' in the command to encode losslessly. Keep in mind that FLAC files are significantly larger than Vorbis files, and that the original AC3 audio in the VOB is itself lossy, so the FLAC output will be a lossless copy of already-compressed audio rather than a true lossless master.
On Linux or macOS you can loop over all VOB files in a directory with: 'for f in *.vob; do ffmpeg -i "$f" -c:a libvorbis -q:a 4 "${f%.vob}.oga"; done'. On Windows Command Prompt use: 'for %f in (*.vob) do ffmpeg -i "%f" -c:a libvorbis -q:a 4 "%~nf.oga"'. Note that DVD rips often split content across multiple numbered VOB files (VTS_01_1.VOB, VTS_01_2.VOB, etc.), so you may want to concatenate them first using FFmpeg's concat demuxer to extract a continuous audio track.
Technical Notes
VOB files follow the MPEG-2 Program Stream specification and are tightly tied to the DVD-Video structure, which means they can contain private data packets, navigation packs, and interleaved subtitle bitmap streams alongside the main audio and video. FFmpeg handles VOB demuxing reliably using the '-f vob' flag internally, but in practice the format is often auto-detected. The AC3 audio in most DVD VOBs is 48 kHz stereo or 5.1 surround at 192–448 kbps; Vorbis at quality level 4 encodes at 44.1 or 48 kHz and is natively stereo, so 5.1 surround channels will be downmixed to stereo during transcoding — this is an important consideration when working with theatrical DVD releases. OGA does not support chapter markers from the DVD structure, and all DVD navigation metadata is discarded. ID3-style metadata tags are not carried over from VOB files, so the resulting OGA will have no embedded title, artist, or track information unless added manually. For very large DVD rip VOBs (over 1 GB), running the FFmpeg command locally on your desktop is recommended for reliability and speed.