VOB to MP4 Converter — Convert DVD Videos Online Free

This video converter transforms DVD VOB (Video Object) files into modern MP4 format using FFmpeg WebAssembly running entirely within the browser. VOB is the container format used on DVD-Video discs, typically wrapping MPEG-2 video, AC-3 (Dolby Digital) or DTS audio, DVD subtitles (bitmap-based), and IFO-referenced navigation data. VOB files follow the MPEG program stream specification and are designed exclusively for DVD player hardware.

The converter loads FFmpeg's WebAssembly core (~31 MB) from a CDN, writes the uploaded VOB file to the virtual filesystem, then executes H.264 re-encoding using the libx264 encoder with the 'fast' preset and CRF 23 — a rate-control mode that targets consistent visual quality (lower CRF = higher quality, 23 is the default "visually lossless" setting). Audio is re-encoded to AAC at 192 kbps for broad compatibility. The -movflags +faststart flag repositions the MP4's moov atom to the beginning of the file, enabling progressive web playback without requiring a full download.

H.264 encoding achieves significantly better compression than the original DVD's MPEG-2 codec — typical VOB files compress 50–70% smaller at equivalent visual quality. FFmpeg's progress callback drives the real-time percentage bar. The resulting MP4 plays natively on every modern device: smartphones, tablets, browsers, smart TVs, and media players. All processing happens locally in the browser — DVD content never leaves the user's device.