Convert VOB to OGG — Free Online Tool
Convert VOB files from DVD discs into OGG audio files, extracting the AC3 (Dolby Digital) or other audio streams and re-encoding them to Vorbis format using Xiph.Org's open, royalty-free codec. This is ideal for archiving DVD audio content — dialogue, music, or commentary tracks — in a compact, open-standard 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 are DVD container files that bundle together MPEG-2 video, AC3 (Dolby Digital) audio, subtitle streams, and sometimes multiple audio tracks into a single multiplexed file. During this conversion, the tool discards the MPEG-2 video stream entirely since OGG is an audio-only container in this context, and re-encodes the AC3 audio track into Vorbis using the libvorbis encoder. AC3 and Vorbis are both lossy codecs but use entirely different compression algorithms, so this is a transcode (not a copy), meaning the audio is decoded from AC3 and re-encoded as Vorbis. The default quality setting of -q:a 4 targets a variable bitrate of roughly 128–160 kbps, which is generally transparent for most listening.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool, which handles the demultiplexing of the VOB container, decoding of the AC3 audio stream, and re-encoding to Vorbis for the OGG output. |
-i input.vob
|
Specifies the input VOB file — the DVD Video Object container holding multiplexed MPEG-2 video, AC3 audio, and potentially subtitle streams. FFmpeg reads and demuxes this file to access the individual streams. |
-c:a libvorbis
|
Sets the audio codec to libvorbis, Xiph.Org's open-source Vorbis encoder. This tells FFmpeg to decode the AC3 audio from the VOB and re-encode it as Vorbis, the standard audio codec for OGG containers. |
-q:a 4
|
Sets the Vorbis encoder to variable bitrate quality level 4, which targets approximately 128–160 kbps. This is the recommended default for general-purpose audio — offering a good balance between file size and perceptual transparency when transcoding from AC3. |
output.ogg
|
Defines the output filename and tells FFmpeg to write the result into an OGG container. Since OGG has no video support in this context, only the re-encoded Vorbis audio stream is written to this file. |
Common Use Cases
- Rip the audio commentary track from a DVD film and save it as an OGG file for listening on a media player that doesn't support VOB or AC3
- Archive a DVD music concert's audio in an open, royalty-free format without depending on proprietary AC3 licensing
- Extract dialogue or narration from a DVD-based educational course into OGG files for use in an open-source e-learning platform
- Convert DVD audio books (stored as VOB files) into OGG so they can be played in open-source software like VLC or Audacity on any platform
- Prepare audio from a DVD game cutscene or soundtrack for use in an open-source game project that requires royalty-free audio formats
- Strip the audio from a VOB file ripped from a home movie DVD to create a standalone OGG recording for archival or sharing
Frequently Asked Questions
Yes, there will be some generation loss because both AC3 and Vorbis are lossy codecs, and this conversion requires fully decoding the AC3 stream and re-encoding it as Vorbis. The audio is never passed through losslessly. However, at the default -q:a 4 setting (roughly 128–160 kbps variable bitrate), Vorbis is considered perceptually transparent for most content, meaning the difference from the original AC3 track is unlikely to be audible under normal listening conditions.
No. OGG is an audio container in this context — it does not support MPEG-2 video streams, so the video content from the VOB file is dropped entirely during conversion. Only the audio track is extracted and re-encoded into Vorbis. If you need to keep the video, you should convert to a format like MKV or MP4 instead.
By default, FFmpeg selects only the best (usually first) audio stream from the VOB file and encodes that single track into OGG. Additional audio tracks — such as a director's commentary or a dubbed language track — and subtitle streams are all discarded, since this command does not specify a stream mapping. OGG does technically support multiple audio streams, but the default command targets a single output track. To extract a specific audio track, you would need to add a flag like -map 0:a:1 to the command.
Adjust the -q:a value, which controls Vorbis variable bitrate quality. The scale runs from 0 (lowest, around 64 kbps) to 10 (highest, around 500 kbps), with 4 being the default (roughly 128–160 kbps). For example, use -q:a 6 for higher quality at approximately 192 kbps, or -q:a 2 for a smaller file at around 96 kbps. Unlike AC3, which uses fixed bitrate settings, Vorbis quality mode adapts the bitrate dynamically based on audio complexity.
Yes, on Linux or macOS you can wrap the command in a shell loop: for f in *.vob; do ffmpeg -i "$f" -c:a libvorbis -q:a 4 "${f%.vob}.ogg"; done. On Windows Command Prompt, use: for %f in (*.vob) do ffmpeg -i "%f" -c:a libvorbis -q:a 4 "%~nf.ogg". This is especially useful for DVD rips split across multiple VOB files (VTS_01_1.vob, VTS_01_2.vob, etc.), though you may want to concatenate them first for a seamless audio output.
This is unlikely if converting at default settings, since Vorbis at -q:a 4 typically produces smaller files than AC3 at its common DVD bitrates of 192–448 kbps. However, if your VOB source contains a high-bitrate AC3 stream (e.g., 448 kbps 5.1 surround), the decoded PCM audio is re-encoded to Vorbis at around 128–160 kbps by default, which should result in a significantly smaller file. If you find the output is larger than expected, check whether your input VOB contains a low-bitrate AC3 track that is being upscaled by the Vorbis encoder — in that case, lower the -q:a value.
Technical Notes
VOB files use the MPEG Program Stream container with AC3 (Dolby Digital) as the standard DVD audio codec, often carrying 5.1 surround sound at bitrates between 192 kbps and 448 kbps. Converting to OGG Vorbis means discarding all multi-channel spatial information unless the Vorbis encoder handles the downmix — by default, FFmpeg will downmix 5.1 AC3 to stereo Vorbis, which may lose surround positioning. If preserving the channel layout is important, you can add -ac 6 to attempt a 5.1 Vorbis encode, though player support for multi-channel Vorbis is less universal. Metadata such as track titles or language tags embedded in VOB streams may not carry over reliably, as VOB metadata structures differ significantly from OGG's Vorbis Comment tagging system. OGG does support chapter markers (unlike VOB's DVD navigation structure), but chapters are not automatically generated from this conversion. There is no video quality parameter involved since video is entirely absent from the output; all conversion effort is focused on the audio transcode from AC3 to Vorbis.