Convert VOB to Y4M — Free Online Tool
Convert VOB files from DVD-Video discs into Y4M (YUV4MPEG2) uncompressed video, decoding the MPEG-2 video stream into raw YUV frame data suitable for lossless video processing pipelines. Y4M is the standard intermediate format used by tools like x264, x265, VapourSynth, and AviSynth when precision matters most.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your VOB file here
or click to browse
Free — no uploads, no signups. Your files never leave your browser.
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 MPEG-2 video (and often AC-3 audio) in a DVD-specific MPEG Program Stream container. During this conversion, FFmpeg fully decodes the MPEG-2 video stream — decompressing every GOP, I-frame, P-frame, and B-frame — into raw uncompressed YUV pixel data. Each frame is then written sequentially into the Y4M container with a minimal per-frame header that records resolution, framerate, and colorspace (typically YUV 4:2:0, matching the DVD source). Audio is not carried over, since Y4M supports only raw video. The result is a frame-accurate, lossless representation of the video content that any tool capable of reading Y4M or rawvideo can consume without further decoding overhead.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary — the engine that will handle reading the VOB container, demuxing the MPEG-2 program stream, decoding the MPEG-2 video, and writing the raw YUV output. |
-i input.vob
|
Specifies the input VOB file. FFmpeg automatically detects the MPEG-2 Program Stream container and identifies the MPEG-2 video stream (and any AC-3 audio or subtitle streams) within it. |
-c:v rawvideo
|
Instructs FFmpeg to encode the output video stream as rawvideo — meaning no compression is applied. Each decoded YUV frame from the MPEG-2 source is written directly into the Y4M output as uncompressed pixel data. |
output.y4m
|
The output filename with the .y4m extension, which causes FFmpeg to automatically select the yuv4mpegpipe muxer. This writes the standard YUV4MPEG2 container format, including the stream header (resolution, framerate, colorspace) and per-frame markers that tools like x264, x265, and VapourSynth expect. |
Common Use Cases
- Feeding DVD-sourced footage into a lossless encoder like x264 or x265 via stdin pipe, bypassing any intermediate lossy transcode
- Importing DVD video into frame-by-frame processing tools like VapourSynth or AviSynth that require uncompressed Y4M input
- Performing reference-quality deinterlacing of interlaced MPEG-2 DVD content using tools that expect raw YUV input (e.g., QTGMC via VapourSynth)
- Creating a pristine uncompressed baseline for visual quality comparisons when evaluating different DVD-to-H.264 or DVD-to-H.265 encode settings
- Extracting specific scenes from a VOB file as uncompressed Y4M for use as source material in video restoration or upscaling workflows
- Archiving the decoded video content of a DVD in a format that can be re-encoded later without accumulating additional generational lossy compression artifacts
Frequently Asked Questions
VOB files use MPEG-2 compression, which achieves high compression ratios by storing only differences between frames (using I, P, and B frames). Y4M is completely uncompressed — every pixel of every frame is stored as raw YUV data. A typical DVD VOB encoded at 6–8 Mbps will expand to roughly 100–200x its original size in Y4M, since standard definition 720x480 or 720x576 video at 25–30fps produces around 200–300 MB per minute of uncompressed YUV 4:2:0 data.
The decoding process itself is mathematically lossless in terms of representing what the MPEG-2 codec encoded. FFmpeg's MPEG-2 decoder will faithfully reconstruct every frame to the exact pixel values the encoder specified. However, any quality limitations already present in the MPEG-2 source — such as compression artifacts, macroblocking, or chroma subsampling at 4:2:0 — are preserved as-is in the Y4M output. Y4M does not add any new quality loss.
Neither audio nor subtitles are included in the Y4M output. Y4M is a video-only format that carries no audio streams, subtitle streams, or metadata beyond basic frame geometry and timing. If you need the AC-3 audio from the VOB, you would need to extract it in a separate FFmpeg command using '-vn -c:a copy' or by transcoding it to another audio format. Subtitle streams (DVD bitmap subtitles) are similarly discarded.
FFmpeg will decode and output the interlaced frames as-is into the Y4M file, preserving the interlaced field structure rather than deinterlacing automatically. The Y4M header will carry the interlacing flag from the source stream (typically 'It' for top-field-first or 'Ib' for bottom-field-first). If you require progressive output, you should add a deinterlace filter to the command, such as '-vf yadif', before piping or writing to Y4M.
You can add '-ss' for a start time and '-t' for duration (or '-to' for an end time) to the command. For example: 'ffmpeg -ss 00:01:30 -i input.vob -t 00:02:00 -c:v rawvideo output.y4m' will extract a 2-minute segment starting at 1 minute 30 seconds. Placing '-ss' before '-i' uses fast seeking, which is generally fine for MPEG-2 sources since FFmpeg will still land accurately on the nearest keyframe.
Yes — this is one of Y4M's primary design purposes. Replace the output filename with a pipe and pass Y4M to stdout: 'ffmpeg -i input.vob -c:v rawvideo -f yuv4mpegpipe - | x264 --demuxer y4m -o output.mp4 -'. The '-f yuv4mpegpipe' flag tells FFmpeg to write the Y4M container format to the pipe, and x264 or x265 can read it directly with '--demuxer y4m'. This avoids writing a multi-gigabyte intermediate file to disk entirely.
Technical Notes
VOB files from DVD-Video discs typically contain MPEG-2 video encoded at resolutions of 720x480 (NTSC) or 720x576 (PAL) with a 4:2:0 chroma subsampling scheme, and the Y4M output will faithfully inherit these characteristics. The rawvideo codec in FFmpeg writes uncompressed YUV 4:2:0 by default when the source is 4:2:0, so no colorspace conversion occurs. One important consideration is that VOB files from a DVD may span multiple VOB files (VTS_01_1.VOB, VTS_01_2.VOB, etc.) split at 1GB boundaries — to process a full title correctly, you should concatenate them first using FFmpeg's concat demuxer or by using the parent VIDEO_TS folder as input. Y4M does not support chapters, multiple audio tracks, or any DVD-specific metadata, so all of this is silently dropped. Because Y4M files can be extremely large (easily several gigabytes for even short clips), the 1GB browser processing limit means this tool is most practical for short DVD segments; the displayed FFmpeg command is especially valuable here for running the full conversion locally on a desktop machine.