Convert VOB to 3G2 — Free Online Tool
Convert VOB files from DVD-Video discs into 3G2 format for CDMA mobile devices, transcoding MPEG-2 video to H.264 and AC3 audio to AAC. This tool runs entirely in your browser — no upload required — making it ideal for quickly extracting and repackaging DVD content into a compact mobile-compatible format.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your VOB file here
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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 contain MPEG-2 video (the standard codec for DVD-Video) and typically AC3 (Dolby Digital) audio, both of which must be fully re-encoded for 3G2 output — this is a true transcode, not a remux. The MPEG-2 video stream is decoded and re-encoded to H.264 using libx264, which delivers far better compression efficiency at the cost of processing time. The AC3 audio is decoded and re-encoded to AAC, the standard audio codec for 3G2 containers. Because VOB files can contain multiple audio tracks, subtitle streams, and DVD menu data, only the primary video and audio stream are mapped to the output — 3G2 does not support subtitles, multiple audio tracks, or chapter markers. The -movflags +faststart flag reorganizes the MP4-style 3G2 container metadata to the front of the file, enabling progressive playback on mobile devices before the full file is downloaded.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary — in this browser-based tool, that is FFmpeg.wasm running as a WebAssembly module entirely within your browser, with no server involved. |
-i input.vob
|
Specifies the input VOB file. FFmpeg will use the VOB demuxer to parse the MPEG program stream, identifying the MPEG-2 video track, AC3 audio track(s), and any subtitle or DVD navigation streams present on the disc. |
-c:v libx264
|
Re-encodes the MPEG-2 video stream from the VOB using the libx264 H.264 encoder. This is a full transcode — the MPEG-2 frames are fully decoded and re-compressed, which is necessary because 3G2 does not support MPEG-2 video. |
-c:a aac
|
Re-encodes the AC3 (Dolby Digital) audio from the VOB to AAC using FFmpeg's native AAC encoder. AAC is the standard audio codec for 3G2 and is far more efficient than AC3 at low mobile bitrates. |
-crf 23
|
Sets the Constant Rate Factor for libx264 to 23, which is the default quality level. For DVD-sourced content where some MPEG-2 compression artifacts already exist, reducing this to 18-20 will better preserve the source quality in the H.264 output. |
-b:a 128k
|
Sets the AAC audio output bitrate to 128 kilobits per second. This is sufficient for mono or stereo dialogue and music from a DVD source when targeting mobile delivery, though the original AC3 track may have been encoded at 192k or higher. |
-movflags +faststart
|
Moves the MP4/3G2 container's metadata (moov atom) to the beginning of the file after encoding completes. This allows CDMA mobile players and streaming clients to begin playback before the entire file has been received. |
output.3g2
|
Defines the output filename and tells FFmpeg to use the 3G2 container format. FFmpeg infers the container from the .3g2 extension, packaging the H.264 video and AAC audio into the 3GPP2-compliant file structure. |
Common Use Cases
- Ripping a DVD movie or TV episode and converting it to a file playable on an older CDMA smartphone or feature phone that only supports 3G2 playback
- Archiving a DVD home video collection in a compact H.264-based format while reducing file size dramatically compared to the original MPEG-2 VOB files
- Preparing a DVD training or instructional video for distribution to mobile field workers whose devices use legacy CDMA network media players
- Extracting a specific VOB chapter from a DVD (such as a music video or short film segment) and converting it to 3G2 for sharing over CDMA MMS messaging
- Converting DVD video content captured from a camcorder disc (miniDVD) into a mobile-friendly 3G2 format for review on a phone without transferring large raw MPEG-2 files
- Testing how DVD-sourced MPEG-2 content degrades through an H.264 transcode at various CRF values before committing to a large batch conversion workflow
Frequently Asked Questions
Yes — this conversion involves two layers of lossy transcoding. The original MPEG-2 video in the VOB is decoded and re-encoded to H.264, and the AC3 audio is decoded and re-encoded to AAC. Each generation of lossy compression introduces some quality degradation. At the default settings (CRF 23, 128k AAC), the output will look noticeably softer than the DVD source, but will be far more compressed. For higher fidelity, lower the CRF value toward 18 and increase the audio bitrate to 192k.
The 3G2 container format does not support multiple audio tracks — it is designed for low-bandwidth mobile delivery and only carries a single video and single audio stream. VOB files commonly contain several audio tracks (e.g., different languages or a commentary track) and subtitle streams, all of which are dropped during this conversion. By default, FFmpeg selects the first detected audio stream from the VOB file. If you need a specific language track, you can use -map 0:a:1 (or the relevant index) in the FFmpeg command to select it manually.
Subtitles are silently dropped. VOB files store DVD subtitles as bitmap-based subtitle streams (DVD SUB format), and the 3G2 container has no support for subtitle tracks of any kind. If preserving subtitles is important, you would need to hard-burn them into the video stream using a libass or overlay filter before encoding — which requires a modified FFmpeg command and is not handled by this tool's default conversion.
The video quality is controlled by the -crf flag, which stands for Constant Rate Factor. The default value of 23 is a middle-ground setting for H.264. Lower values produce higher quality and larger files — CRF 18 is generally considered visually near-lossless for most DVD content, while CRF 28 will produce a smaller but noticeably softer file. For DVD-sourced MPEG-2 content that already has some compression artifacts, a CRF between 18 and 22 is recommended to avoid compounding quality loss.
Yes — the displayed FFmpeg command can be adapted for batch processing in a terminal. On Linux or macOS, you can run: for f in *.vob; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k -movflags +faststart "${f%.vob}.3g2"; done. On Windows Command Prompt, use a for loop: for %f in (*.vob) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 128k -movflags +faststart "%~nf.3g2". Note that the browser-based tool processes files one at a time and has a 1GB limit, making local FFmpeg the better choice for bulk DVD ripping workflows.
Because both the video and audio streams must be fully re-encoded rather than copied, this conversion is computationally intensive. Decoding MPEG-2 and re-encoding to H.264 via libx264 is one of the more CPU-demanding operations in FFmpeg, especially for DVD-resolution (720x480 or 720x576) content. When using this browser-based tool with FFmpeg.wasm, the processing happens entirely on your device's CPU without GPU acceleration, which makes it slower than native FFmpeg. For large VOB files or batch jobs, running the FFmpeg command locally on your desktop will be significantly faster.
Technical Notes
VOB files are a wrapper around a program stream of MPEG-2 video, AC3 audio, and DVD-specific navigation data (NAV packets). When processed by FFmpeg, the -f vob demuxer is used to correctly parse the container, including handling the interleaved structure of MPEG program streams. The libx264 encoder used for the output is not natively included in all FFmpeg builds, but is present in FFmpeg.wasm and standard distribution builds. The 3G2 format is structurally very similar to MP4 (both derive from the ISO Base Media File Format), which is why the -movflags +faststart flag — normally associated with MP4 web streaming — applies here as well. One important limitation is that VOB files from commercial DVDs are often encrypted with CSS (Content Scrambling System), which FFmpeg cannot decrypt on its own; you must use a decrypted source VOB. Additionally, DVD titles are frequently split across multiple VOB files (e.g., VTS_01_1.VOB, VTS_01_2.VOB), and concatenating them before conversion using FFmpeg's concat demuxer will yield a single continuous output rather than multiple fragmented 3G2 files. The resulting 3G2 files will be considerably smaller than the source VOB due to H.264's superior compression efficiency over MPEG-2, typically achieving a 3x to 5x reduction in file size at comparable visual quality.