Convert VOB to MP3 - extract audio
VOB files hold the video content on every DVD Video disc. Audio is almost always AC-3 (Dolby Digital), sometimes MP2, occasionally DTS - all covered in Audio codecs explained. Wave decodes the primary audio track, downmixes multi-channel to stereo, and encodes MP3 at 192 kbps.
What actually changes
A VOB file is the DVD Video specification's container: an MPEG-2 Program Stream carrying MPEG-2 video, one or more audio tracks, subpictures for subtitles, and navigation data. On a DVD disc these files live in `VIDEO_TS/VTS_*.VOB`, split into segments of up to 1 GB each. Wave reads the file, discards the video and subpicture streams entirely, and decodes only the primary audio track.
Audio in a VOB is almost always AC-3 (also known as Dolby Digital), because DVD-Video 1.0 in 1996 mandated AC-3 stereo or 5.1 as the primary audio format for NTSC-region discs. Some European PAL DVDs used MP2 as the primary audio (permitted by the DVD spec as an alternative); a smaller share of releases carried DTS as an additional track. Wave's wasm engine decodes all three codecs and re-encodes to MP3 at 192 kbps through libmp3lame.
The DVD-Video specification, ratified in 1996 and used essentially unchanged for the next two decades, is why nearly every VOB you can play today has AC-3 audio. AC-3 was chosen over MP2 for NTSC discs because Dolby Digital 5.1 was already the theatrical audio standard, and mandating it made every DVD player capable of driving a surround-sound system. MP2 stayed common on European PAL DVDs because European broadcasting had built its infrastructure around MP2 audio (MPEG-1 Layer II is the audio codec of every DVB broadcast). Both codecs are lossy, so the MP3 extract is a re-encode of a re-encode - but at 192 kbps the audible difference on consumer gear is nil.
The downmix behaviour matters when the source is AC-3 5.1. AC-3 streams carry downmix metadata (Lt/Rt and Lo/Ro coefficients) telling the decoder how to fold surround channels into stereo without losing dialogue intelligibility. Wave respects these coefficients through the ffmpeg AC-3 decoder, so the resulting stereo MP3 keeps the dialogue centred and the effects roughly where they were in the original mix. If you want to preserve the surround layout, MP3 isn't the right target - use a lossless multi-channel format instead.
Three steps.
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01
Step 1
Drop a .vob file onto the card.
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Step 2
Pick MP3 as the output format.
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Step 3
Convert. Save the MP3.
Answers, specifically.
My DVD has several VOB files. Which one should I convert?
The largest one, usually. On a DVD, the main title (feature film or main content) is split across VOBs named `VTS_01_1.VOB`, `VTS_01_2.VOB`, and so on. The first is often the smallest (menu / intro chapter); the middle ones are the largest and hold the bulk of the content. Concatenate them first with a desktop tool if you need continuous audio.
Will 5.1 AC-3 sound audible as stereo MP3?
Yes. AC-3's downmix metadata is respected, so dialogue stays centred and effects preserve their approximate stereo positions. The surround-only content (rear-channel ambience) folds into the stereo field.
DTS audio support?
Yes. Wave's wasm engine includes a DTS decoder. DTS is less common on DVDs than AC-3 - it was optional in the DVD-Video spec, mainly used for high-fidelity music DVDs and some deluxe film releases - but where it is present, Wave decodes and re-encodes cleanly.
MP2-only PAL DVDs?
Yes. European DVDs with MP2 as the primary audio are common; the decoder is included, and MP2 stereo folds directly into MP3 stereo.
Multi-angle DVD titles - which angle's audio does Wave get?
Only one audio track is bound to each angle in the DVD spec. Wave takes the default audio stream, which corresponds to the primary angle.
CSS-encrypted DVDs?
Wave can't decrypt CSS (the DVD-Video Content Scramble System). If your VOB files were extracted from a CSS-encrypted disc with a tool like libdvdcss or MakeMKV, they land as plaintext MPEG-2 Program Streams and Wave handles them normally. If they're still CSS-encrypted, decryption has to happen first.
Does Wave read the IFO chapter navigation?
No. IFO files carry the navigation metadata (chapter points, angle selection, subtitle timing). Wave reads the VOB's audio and video streams directly, without following the IFO navigation. If you need chapter breaks in the output, a desktop tool like HandBrake reads IFO files and can produce chaptered MP3 or M4B output.
The audio has a slight sync offset - why?
DVD Program Streams sometimes carry PTS (Presentation Timestamp) offsets that assume the video and audio start at slightly different times. Wave preserves the audio's original timing, which usually matches the source disc exactly. If your VOB was extracted from a damaged disc or over an unreliable IDE cable, individual frames might have been dropped - the resulting sync drift is baked into the source and can't be fixed post-hoc.