Convert VOB to 3GP — Free Online Tool
Convert DVD VOB files to 3GP format, re-encoding the MPEG-2 video to H.264 and the AC-3 audio to AAC — making DVD content playable on older 3G mobile phones and low-bandwidth mobile devices. This tool runs entirely in your browser with no file uploads required.
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 store DVD video as MPEG-2 streams with AC-3 (Dolby Digital) audio, typically at resolutions like 720x480 (NTSC) or 720x576 (PAL) with high bitrates suited for disc playback. Converting to 3GP requires a full re-encode of both streams: the MPEG-2 video is transcoded to H.264 using libx264, which achieves far better compression at lower bitrates suitable for mobile delivery. The AC-3 audio track is transcoded to AAC at 64k, a significant reduction from the 192–448k bitrates common in DVD audio. The scale filter ensures the output dimensions are divisible by 2, which H.264 encoding requires. Because VOB files can contain multiple audio tracks and subtitle streams, only the first (default) audio track is carried over, and subtitles are dropped since 3GP does not support them.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool, which handles the full re-encoding pipeline needed to convert a DVD VOB's MPEG-2/AC-3 streams into the H.264/AAC streams required by the 3GP container. |
-i input.vob
|
Specifies the source VOB file as input. FFmpeg automatically detects the MPEG program stream structure, identifies the MPEG-2 video track and AC-3 audio track(s), and makes them available for re-encoding. |
-c:v libx264
|
Transcodes the MPEG-2 video from the VOB into H.264 using the libx264 encoder — the codec required for video in 3GP files and one that achieves far superior compression than MPEG-2 at mobile-appropriate bitrates. |
-c:a aac
|
Transcodes the AC-3 Dolby Digital audio from the DVD VOB into AAC, which is the standard audio codec supported by 3GP and by 3G mobile devices. AC-3 is not supported in the 3GP container, making this re-encode mandatory. |
-crf 23
|
Sets the Constant Rate Factor for the H.264 encoder to 23, a medium-quality setting that balances file size and visual fidelity. Since the source MPEG-2 video may be 4–8 Mbps, this CRF will result in significant bitrate reduction suitable for mobile playback. |
-b:a 64k
|
Sets the AAC audio output bitrate to 64 kilobits per second, a standard low-bandwidth target for 3GP audio that replaces the much higher 192–448kbps AC-3 bitrate typically used in DVD VOB files. |
-vf scale=trunc(iw/2)*2:trunc(ih/2)*2
|
Applies a video filter that rounds the output width and height down to the nearest even numbers. This is required because H.264 encoding in a 3GP container demands even dimensions, and DVD VOB resolutions can sometimes produce odd pixel counts after scaling or aspect ratio correction. |
output.3gp
|
Defines the output file with the .3gp extension, which tells FFmpeg to use the 3GP container format — a mobile-optimized MPEG-4 variant originally standardized for 3G phone video delivery. |
Common Use Cases
- Archiving a personal DVD rip as a compact 3GP file to store dozens of movies on an older mobile phone with limited storage
- Sharing a short DVD-sourced video clip with someone whose only playback device is a basic 3G handset without MP4 support
- Converting a DVD training video or instructional disc into a mobile-friendly format for field workers using legacy corporate phones
- Reducing the file size of a VOB segment from a home DVD recording for MMS sharing over a mobile network with strict size limits
- Preparing DVD-sourced video content for streaming on low-bandwidth or 3G-only cellular connections where H.264 in 3GP offers the best compatibility
- Converting a VOB menu or bonus clip from a DVD into a small 3GP preview file for a mobile portfolio or demo reel
Frequently Asked Questions
No — AC-3 (Dolby Digital) audio from the VOB, which may be 5.1 surround at 192–448kbps, is transcoded to stereo AAC at 64kbps in the 3GP output. The 3GP format does not support AC-3, and its target devices (3G mobile phones) are designed for mono or stereo playback anyway. The audio will be down-mixed to two channels and compressed significantly, which is expected for mobile delivery.
The original MPEG-2 video on a DVD is typically encoded at 4–8 Mbps, while the H.264 output in 3GP uses a CRF of 23, which targets a much lower bitrate suited for mobile screens. Additionally, 3GP files are optimized for small displays, so the re-encoded H.264 video may be noticeably softer when viewed on a large screen. For best results on small mobile screens, the quality difference is much less apparent.
Only the default (first) audio track from the VOB is included in the 3GP output, because 3GP does not support multiple audio tracks. If you need a specific language track other than the default, you would need to modify the FFmpeg command to add '-map 0:a:1' (or another index) to select the desired audio stream before converting.
No. VOB files can contain DVD subtitle streams (VOBsub format), but 3GP does not support subtitle streams at all. Subtitles are silently dropped during the conversion. If you need subtitles on the output, you would need to burn them into the video using FFmpeg's subtitle filter before the 3GP conversion, which requires an additional step.
The CRF (Constant Rate Factor) value controls video quality: lower numbers mean better quality and larger files, higher numbers mean smaller files with more compression. The default is '-crf 23'. To reduce file size for very limited mobile storage, try '-crf 28' or '-crf 30'. To improve visual quality at the cost of file size, try '-crf 18'. For 3GP files destined for very small screens, values of 26–30 are typically indistinguishable from lower CRF values.
Yes. On Linux or macOS, you can run: 'for f in *.vob; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 64k -vf scale=trunc(iw/2)*2:trunc(ih/2)*2 "${f%.vob}.3gp"; done'. On Windows Command Prompt, use: 'for %f in (*.vob) do ffmpeg -i "%f" -c:v libx264 -c:a aac -crf 23 -b:a 64k -vf scale=trunc(iw/2)*2:trunc(ih/2)*2 "%~nf.3gp"'. This is particularly useful for converting all VOB chapters from a DVD rip in one pass.
Technical Notes
VOB files are structurally DVD-Video containers using MPEG program stream multiplexing, and they often contain encrypted or copy-protected streams when sourced directly from a commercial disc — FFmpeg can only process unprotected or already-ripped VOB files. The MPEG-2 video inside a VOB is interlaced in most DVD productions (especially for broadcast-sourced content), and this interlacing is passed through to the H.264 encoder unless you add a deinterlace filter like '-vf yadif,scale=trunc(iw/2)*2:trunc(ih/2)*2'. The scale filter used in this command (trunc(iw/2)*2:trunc(ih/2)*2) is essential because H.264 in a 3GP container requires width and height to be even numbers, and some DVD resolutions (particularly after aspect ratio adjustments) can produce odd dimensions that would otherwise cause an encoding error. The output 3GP file uses the .3gp container, which is a restricted subset of MPEG-4 Part 12, and is not the same as .mp4 despite sharing some codec compatibility. File sizes will typically shrink dramatically — a 1GB VOB chapter might become 50–150MB in 3GP — but at the cost of both video and audio quality due to the heavy bitrate reduction required for mobile compatibility.