Convert VOB to ALAC — Free Online Tool
Convert VOB files from DVD discs to ALAC (Apple Lossless Audio Codec), extracting the AC3/Dolby Digital audio track and re-encoding it to a bit-perfect lossless format stored in an MPEG-4 container. Ideal for archiving DVD audio content — such as concert films, audio commentaries, or music DVDs — to an iTunes- and Apple Music-compatible lossless format.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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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 contain multiplexed streams: MPEG-2 video, AC3 (Dolby Digital) audio, and often subtitles. This conversion discards the video and subtitle streams entirely, extracting only the audio. The AC3 audio track — which is a lossy, compressed format — is then decoded to PCM and re-encoded using Apple's ALAC codec. ALAC is lossless in the sense that it compresses the decoded PCM without any further quality loss, so the output preserves every sample of the decoded audio exactly. However, since the original AC3 source is lossy, the final ALAC file reflects the quality ceiling of that AC3 encode rather than studio-master fidelity. The output is wrapped in an .m4a (MPEG-4 Audio) container, which is fully compatible with iTunes, Apple Music, and iOS devices.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg multimedia processing tool, which handles the decoding of the VOB container and all stream processing for this conversion. |
-i input.vob
|
Specifies the input VOB file. FFmpeg parses the MPEG Program Stream container to identify all available streams — typically an MPEG-2 video stream, one or more AC3 audio streams, and possibly DVD subtitle streams. |
-c:a alac
|
Instructs FFmpeg to encode the audio stream using Apple's Lossless Audio Codec (ALAC). This decodes the source AC3 audio to PCM and then compresses it losslessly, producing output that is bit-for-bit identical to the decoded AC3 audio without introducing any new compression artifacts. |
-c:a alac
|
A repeated instance of the same audio codec flag — redundant in this command but harmless, as FFmpeg applies the last value. The effective result is identical: ALAC encoding is applied to the audio output. |
output.m4a
|
Defines the output filename with the .m4a extension, which signals an MPEG-4 Audio container — the standard and expected wrapper for ALAC files in the Apple ecosystem. FFmpeg automatically omits the video stream because the .m4a container does not support MPEG-2 video, resulting in an audio-only output file. |
Common Use Cases
- Ripping the audio from a music DVD or concert Blu-ray backup in VOB format to create a lossless ALAC library in iTunes or Apple Music
- Preserving the full AC3 audio from a DVD commentary track or audio book DVD in a lossless intermediate format for editing in GarageBand or Logic Pro
- Archiving the audio from home movie DVDs (burned from camcorder footage) to ALAC so no additional generation loss is introduced when re-editing later
- Converting a DVD audio track for playback on an Apple device like iPhone or Apple TV via a local media library, where ALAC receives native hardware decoding support
- Extracting lecture or educational DVD audio into ALAC for archival purposes before transcoding further to smaller formats like AAC for distribution
- Preparing DVD-sourced audio for import into Final Cut Pro or Logic Pro projects that benefit from the lossless ALAC format over lossy AC3
Frequently Asked Questions
No — ALAC is lossless relative to its input, but that input is the decoded AC3 audio from the VOB, which is itself a lossy format. The conversion decodes AC3 to raw PCM and then compresses that PCM losslessly with ALAC, so the ALAC file will sound identical to the AC3 source without any further degradation. Think of ALAC here as a quality-preserving container for whatever the AC3 track contained, not an upgrade beyond it.
ALAC-encoded audio is standardly stored inside an MPEG-4 container, which uses the .m4a file extension — this is the native and expected format for ALAC files across the Apple ecosystem. ALAC does not have its own standalone container format the way FLAC does. The .m4a extension signals to iTunes, Apple Music, iOS, and macOS that the file contains Apple Lossless audio, ensuring proper recognition and native playback.
By default, FFmpeg selects the first audio stream it finds in the VOB file, which is typically the primary language track. If you need to extract a specific audio track — for example, the French dub or an isolated music-and-effects track — you can modify the command by adding a stream specifier such as -map 0:a:1 to select the second audio stream. This tool extracts only one audio track at a time into the single-track ALAC output.
The -c:a alac flag instructs FFmpeg to encode the audio stream using the Apple Lossless Audio Codec. In this specific command it appears twice, which is redundant but harmless — FFmpeg applies the last specified value, so the result is identical to using it once. The effective instruction is: take the audio decoded from the VOB's AC3 stream and re-encode it as ALAC, discarding all video data since the output container (.m4a) does not support video.
On macOS or Linux, you can run a shell loop in your terminal: for f in *.vob; do ffmpeg -i "$f" -c:a alac "${f%.vob}.m4a"; done. On Windows Command Prompt, use: for %f in (*.vob) do ffmpeg -i "%f" -c:a alac "%~nf.m4a". This processes each VOB file in the current directory and outputs a corresponding .m4a file with ALAC audio. This is especially useful for ripping a multi-VOB DVD where each VOB represents a chapter or title.
The ALAC audio file will be dramatically smaller than the original VOB because the video stream — which typically accounts for 70–90% of a VOB's file size — is completely discarded. The audio portion of a typical DVD AC3 track runs at 192–448 kbps; after lossless re-encoding to ALAC, the .m4a file size will be roughly proportional to the audio duration and bitrate of the source AC3 stream. A 60-minute VOB that is several gigabytes may yield an ALAC file of only 200–500 MB.
Technical Notes
VOB files use the MPEG Program Stream container and typically carry AC3 (Dolby Digital) audio at bitrates between 192 kbps and 448 kbps, encoded at 48 kHz sample rate with up to 5.1 surround channels. ALAC supports multi-channel audio, so stereo and 5.1 AC3 tracks are both handled correctly — the channel layout is preserved during the PCM-to-ALAC encoding step. Metadata from VOB files is sparse (DVD IFO structures carry titles and chapter info, not embedded ID3-style tags), so the resulting .m4a file will likely have minimal metadata; you should tag it manually in iTunes or a tool like MusicBrainz Picard after conversion. ALAC does not support subtitle streams, and the .m4a container does not support the video codecs found in VOB files (MPEG-2), so this conversion is strictly audio-only. If your VOB contains DTS audio instead of AC3, FFmpeg will still handle the decode correctly, but you should verify the primary audio stream type beforehand using ffprobe. Files processed in the browser via FFmpeg.wasm are limited to 1 GB; larger multi-VOB DVD rips should use the displayed FFmpeg command locally.