Extract Audio from VOB to AAC — Free Online Tool
Extract the AC-3 (Dolby Digital) audio track from a VOB file and convert it to AAC format — ideal for pulling high-quality audio from DVD rips without re-encoding the video. AAC delivers excellent sound quality at compact file sizes, making it perfect for use on modern devices and streaming platforms that don't support AC-3.
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 DVD container files that typically carry MPEG-2 video alongside one or more AC-3 (Dolby Digital) audio tracks, and sometimes DTS or MPEG audio as well. This tool discards the video stream entirely and transcodes the default AC-3 audio track into AAC using FFmpeg's built-in AAC encoder. Because AC-3 and AAC are both lossy formats with different compression algorithms, this is a full decode-and-re-encode operation — the AC-3 audio is first decoded to uncompressed PCM, then re-encoded as AAC at the target bitrate (128k by default). The result is a standalone .aac audio file containing only the audio, with no video data.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool. In the browser, this runs via FFmpeg.wasm (WebAssembly), so no software installation is needed and no files leave your device. |
-i input.vob
|
Specifies the input VOB file — a DVD Video Object container carrying multiplexed MPEG-2 video, AC-3 audio, and possibly subtitle streams. |
-vn
|
Disables video output entirely, telling FFmpeg to ignore the MPEG-2 video stream in the VOB file. This ensures the output is audio-only and keeps the resulting AAC file small. |
-c:a aac
|
Selects FFmpeg's built-in AAC encoder to transcode the AC-3 audio from the VOB into AAC LC format — the most widely supported AAC profile across Apple devices, Android, and web browsers. |
-b:a 128k
|
Sets the target audio bitrate for the AAC output to 128 kilobits per second. This is a standard quality level suitable for most listening scenarios; increase to 192k or 256k if the source AC-3 track is music or high-fidelity content. |
output.aac
|
Defines the output filename and format. The .aac extension tells FFmpeg to write a raw AAC bitstream. Changing this to .m4a would instead wrap the same AAC audio in an MPEG-4 container, which offers better metadata support and broader device compatibility. |
Common Use Cases
- Extracting the audio commentary or dialogue from a DVD rip (VOB file) to listen to on a phone or tablet that doesn't support AC-3 playback
- Pulling a music concert's audio from a DVD-Video VOB file to create a portable AAC audio file for iTunes or Apple Music
- Converting the audio from a DVD-based language learning course into AAC files for use in a podcast app or mobile audio player
- Stripping the audio track from a DVD movie backup to create a compact AAC file for use as background music or ambient sound
- Extracting interview or lecture audio from a DVD-authored recording for upload to a platform like YouTube or a podcast host that prefers AAC
- Converting a DVD documentary's audio track to AAC for archival or transcription purposes without keeping the large MPEG-2 video data
Frequently Asked Questions
Yes, some generation loss is unavoidable. VOB files typically carry AC-3 (Dolby Digital) audio, which is already a lossy format. Converting to AAC requires decoding the AC-3 back to raw PCM audio and then re-encoding it using a different lossy algorithm. This double-compression can introduce subtle artifacts. At 128k AAC the result is perfectly acceptable for casual listening, but if maximum fidelity is your goal, consider using a higher bitrate like 192k or 256k to minimize the impact of re-encoding.
By default, FFmpeg selects the first audio stream it finds in the VOB file, which is typically the primary language track. DVD VOB files often contain multiple audio streams (e.g., different languages or a director's commentary). If you need a specific track, you can modify the FFmpeg command to add '-map 0:a:1' (for the second audio track) before the output filename. You can inspect all available streams first by running 'ffmpeg -i input.vob' in a terminal.
The .aac extension produces a raw AAC bitstream, while .m4a wraps the same AAC audio inside an MPEG-4 container with better metadata support. Both contain AAC-encoded audio, but .m4a is generally more compatible with Apple devices, iTunes, and most modern media players. If you plan to use the file in iTunes or on an iPhone, simply changing the output filename extension from .aac to .m4a in the FFmpeg command will produce a more compatible file.
The '-b:a 128k' flag controls the output AAC bitrate. You can replace '128k' with any supported value such as '96k' for a smaller file, '192k' for better quality, or '256k' and '320k' for near-transparent quality. For typical speech or mono content from a DVD extra, 96k is usually sufficient. For music or surround-downmixed content, 192k or higher is recommended to preserve audio fidelity after the AC-3-to-AAC transcode.
Yes — on Linux or macOS you can run a shell loop: 'for f in *.vob; do ffmpeg -i "$f" -vn -c:a aac -b:a 128k "${f%.vob}.aac"; done'. On Windows Command Prompt use: 'for %f in (*.vob) do ffmpeg -i "%f" -vn -c:a aac -b:a 128k "%~nf.aac"'. This processes every VOB file in the current directory and outputs a matching .aac file for each one, which is especially useful when dealing with a multi-episode DVD rip split across several VOB files.
VOB files are DVD container files and carry very limited metadata — they don't store ID3-style tags like artist, album, or title the way MP3 or M4A files do. As a result, the output AAC file will typically have no embedded metadata tags. If you want to add metadata to the resulting AAC file, you can do so with a tag editor like MusicBrainz Picard, iTunes, or by appending FFmpeg metadata flags such as '-metadata title="My Track"' to the command before the output filename.
Technical Notes
VOB files use the MPEG program stream container and almost universally carry AC-3 (Dolby Digital) audio, often at bitrates between 192k and 448k, and frequently in 5.1 surround format. When converting to AAC, FFmpeg's built-in AAC encoder performs a stereo downmix by default if the source is multichannel — meaning your 5.1 surround audio will be folded down to two channels in the output. If you need to preserve all channels, add '-ac 6' to the command; however, note that raw .aac files have limited multichannel support, and you may want to target .m4a instead. The default AAC encoder in FFmpeg produces compliant LC-AAC output that is compatible with iOS, Android, iTunes, and most web browsers. The alternative 'libfdk_aac' encoder (if available in your FFmpeg build) produces marginally higher quality output at the same bitrate, achieved by substituting '-c:a libfdk_aac' in the command. Because both AC-3 and AAC are lossy formats, running this conversion on a DVD rip rather than a lossless source means you are working with already-compressed audio — keep target bitrates at 128k or above to avoid audible degradation.