Convert VOB to M4A — Free Online Tool
Convert VOB files from DVD discs into M4A audio, extracting the AC3 or MPEG audio track and re-encoding it as AAC inside an MPEG-4 container. Ideal for ripping DVD soundtrack albums, concert films, or audio commentary tracks into a format compatible with iTunes, iPhones, and modern media players.
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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-Video container files that multiplex MPEG-2 video, AC3 (Dolby Digital) audio, subtitle streams, and sometimes multiple audio tracks into a single file. This conversion strips away the video, subtitle, and menu data entirely and re-encodes the primary audio track — typically AC3 at 192–448 kbps — into AAC audio inside an M4A container. Because AC3 and AAC are different codecs, a full audio transcode is required; the audio is decoded from AC3 and re-encoded to AAC at 128 kbps by default. The M4A output is an audio-only MPEG-4 file with no video stream, making it significantly smaller than the source VOB and directly playable in iTunes, Apple Music, and any AAC-compatible player.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary. This is the same underlying engine running in your browser via WebAssembly — the command shown is identical to what you would run on your local machine with FFmpeg installed. |
-i input.vob
|
Specifies the input VOB file. FFmpeg automatically detects the MPEG Program Stream container and identifies the multiplexed MPEG-2 video, AC3 audio, and subtitle streams contained within the DVD-Video file. |
-c:a aac
|
Transcodes the audio stream to AAC (Advanced Audio Coding) using FFmpeg's built-in AAC encoder. This is required because AC3 (the native DVD audio codec in the VOB) is not compatible with the M4A container, which expects AAC or other MPEG-4 audio codecs. |
-b:a 128k
|
Sets the AAC audio bitrate to 128 kilobits per second. This is a reasonable default for voice and general audio content; for music extracted from concert or film DVDs, consider increasing this to 192k or 256k to better preserve dynamic range and high-frequency content lost in the AC3-to-AAC transcode. |
-vn
|
Disables video output entirely, discarding the MPEG-2 video stream from the VOB. This flag is essential because M4A is a audio-only container and cannot hold a video stream; omitting it would cause the conversion to fail or produce an invalid file. |
output.m4a
|
The output filename with the .m4a extension, which tells FFmpeg to wrap the encoded AAC audio in an MPEG-4 audio container. The resulting file is directly compatible with Apple iTunes, Apple Music, iPhones, and any player that supports AAC-LC audio. |
Common Use Cases
- Rip the audio from a DVD concert film or live performance disc to create an M4A music album playable in Apple Music or on an iPhone
- Extract a DVD film's original score or soundtrack for personal archiving in an iTunes library
- Convert a DVD audiobook or lecture series stored as VOB files into M4A episodes for listening on a commute
- Pull the audio commentary track from a DVD special edition VOB file for standalone listening
- Extract audio from a DVD-based karaoke disc to create M4A backing tracks for practice sessions
- Archive a DVD-based language learning course by converting the VOB audio into individual M4A lesson files
Frequently Asked Questions
Yes, there is a generational quality loss because this is a lossy-to-lossy transcode. The AC3 audio in the VOB is fully decoded to uncompressed PCM and then re-encoded as AAC. At the default 128 kbps AAC output, most listeners find the result transparent for speech and adequate for music, but audiophiles may prefer bumping the bitrate to 192k or 256k using the -b:a flag. For critical listening purposes, the source AC3 audio at 192–448 kbps is technically higher fidelity, so only go lower if file size is a priority.
AC3 from a DVD is often 5.1 surround (six channels), while the default AAC encoding in this command will downmix the channels based on FFmpeg's defaults — typically to stereo if your playback device or the encoder requests it. If you want to preserve 5.1 surround in the M4A, add -ac 6 to the command before the output filename. Note that M4A with multichannel AAC has limited player support compared to stereo.
Adjust the -b:a flag to change the AAC bitrate. For example, replace -b:a 128k with -b:a 192k or -b:a 256k for higher quality output. 128k is a reasonable default for speech, but for music extracted from concert or soundtrack DVDs, 192k or 256k will preserve more high-frequency detail. The M4A format supports bitrates from 64k up to 320k for AAC.
Yes. VOB files from DVDs commonly contain multiple audio streams (e.g., English AC3, French AC3, director's commentary). To select a specific stream, add -map 0:a:1 before the output filename to pick the second audio track (zero-indexed), or use -map 0:a:2 for the third, and so on. You can first run ffprobe input.vob to list all available audio streams and identify the one you want.
FFmpeg doesn't natively batch process files in one command, but you can use a shell loop. On Linux or macOS, run: for f in *.vob; do ffmpeg -i "$f" -c:a aac -b:a 128k -vn "${f%.vob}.m4a"; done. On Windows Command Prompt, use: for %f in (*.vob) do ffmpeg -i "%f" -c:a aac -b:a 128k -vn "%~nf.m4a". This is especially useful when ripping individual chapters from a DVD that stores each title as a separate VOB file.
No. VOB files do not embed chapter metadata in a way FFmpeg can automatically map to M4A chapters during this conversion, and DVD menu/navigation data is not transferred. Basic metadata tags (like title) are also unlikely to carry over from VOB source files. If you want chapter markers in the M4A, you would need to add them manually after conversion using a tool like mp4chaps or by editing the file in iTunes or a tag editor.
Technical Notes
VOB files use the MPEG Program Stream container and are tightly coupled to the DVD-Video specification. The audio in a VOB is almost universally AC3 (Dolby Digital) at 48 kHz sample rate, though some discs carry DTS, LPCM, or MPEG audio. FFmpeg reads VOB files using the -f vob demuxer hint internally, which helps disambiguate them from generic MPEG Program Stream files. The -vn flag is critical here — without it, FFmpeg would attempt to process the MPEG-2 video stream and fail or create invalid output since M4A has no video track support. The AAC encoder used is FFmpeg's native aac encoder, which produces compliant MPEG-4 AAC-LC audio — the most broadly compatible AAC profile for iTunes, iOS, Android, and web browsers. One known limitation: if a VOB file is part of a multi-file DVD title (e.g., VTS_01_1.VOB, VTS_01_2.VOB), each file will be converted independently, potentially splitting audio mid-track. For seamless concatenation, consider using FFmpeg's concat demuxer to join the VOBs first. Also note that encrypted commercial DVDs cannot be processed directly and require decryption before conversion.