Convert Y4M to VOB — Free Online Tool
Convert Y4M (YUV4MPEG2) lossless uncompressed video into VOB format, encoding the raw video stream as MPEG-2 and audio as AC3 Dolby Digital — the native codec combination used on DVD-Video discs. Ideal for preparing professionally processed video for DVD authoring workflows.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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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
Y4M files store raw, uncompressed YUV frames with no video encoding — every pixel value is preserved exactly as-is, making it a true lossless intermediate. During this conversion, FFmpeg reads those uncompressed frames and encodes them using the MPEG-2 video codec, applying lossy DCT-based compression to produce a compact bitstream compatible with DVD players. Since Y4M typically carries no audio stream, any audio present is encoded to AC3 (Dolby Digital) at 192k bitrate, the standard audio format found on DVD-Video. The output is wrapped in the VOB container using the -f vob flag, which structures the multiplexed MPEG-2 video and AC3 audio into the format expected by DVD authoring tools and hardware players. Because the source is uncompressed, the MPEG-2 encoder has access to full-quality input with no prior generation loss, meaning the quality ceiling is as high as the MPEG-2 codec allows.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg tool, which handles all reading, encoding, and muxing operations in this conversion pipeline — here running inside the browser via WebAssembly (FFmpeg.wasm). |
-i input.y4m
|
Specifies the input file in Y4M (YUV4MPEG2) format, an uncompressed video container whose plain-text frame headers tell FFmpeg the resolution, frame rate, and chroma subsampling of the raw YUV data. |
-c:v mpeg2video
|
Encodes the uncompressed Y4M video frames using the MPEG-2 video codec, the standard video encoding used on DVD-Video discs and required for VOB compatibility with hardware DVD players. |
-c:a ac3
|
Encodes the audio stream as AC3 (Dolby Digital), the primary audio format specified by the DVD-Video standard and natively supported by virtually all DVD players and home theater receivers. |
-q:v 4
|
Sets the MPEG-2 video quality using the quantizer scale, where 1 is the highest quality and 31 is the lowest. A value of 4 offers a good balance of visual fidelity and file size appropriate for DVD-quality output from a pristine uncompressed Y4M source. |
-b:a 192k
|
Sets the AC3 audio bitrate to 192 kilobits per second, which is the standard DVD-Video bitrate for stereo Dolby Digital audio and provides clear, compatible audio output. |
-f vob
|
Explicitly forces FFmpeg to use the VOB muxer rather than defaulting to the generic MPEG Program Stream muxer, ensuring the output file is correctly structured for DVD playback hardware and authoring software. |
output.vob
|
The name of the output file in VOB format, containing the multiplexed MPEG-2 video and AC3 audio streams ready for use in a DVD authoring workflow or direct playback in a DVD-capable media player. |
Common Use Cases
- Preparing lossless Y4M footage exported from video processing pipelines (such as AviSynth or VapourSynth) for DVD authoring software like DVDAuthor or IFOEdit
- Converting uncompressed Y4M intermediate files from video restoration or upscaling projects into a DVD-compatible format for disc burning
- Archiving processed Y4M content from ffmpeg pipe-based workflows as DVD-Video VOB files that can be played on standalone DVD players
- Encoding Y4M test sequences or reference video into MPEG-2 VOB for compatibility testing with DVD playback hardware and software
- Packaging uncompressed Y4M film scans or digitized analog video into the DVD VOB format for distribution on physical media
- Converting Y4M output from motion compensation or frame interpolation tools into VOB files as input for a DVD disc image creation workflow
Frequently Asked Questions
Yes, this conversion is lossy — MPEG-2 uses DCT-based compression that discards visual information, unlike Y4M which stores every pixel uncompressed. However, because Y4M provides a pristine, generation-loss-free source, the MPEG-2 encoder receives the best possible input, minimizing compression artifacts compared to re-encoding an already-compressed source. At the default quality setting of -q:v 4, the output is visually quite good for DVD-resolution content, though fine detail and high-motion scenes may show typical MPEG-2 blocking at lower bitrates.
VOB files from this conversion contain valid MPEG-2 video and AC3 audio, which are the correct elementary streams for DVD-Video, but most DVD authoring tools (such as DVDAuthor, Nero, or ImgBurn) require the video to conform to specific DVD-Video constraints: resolutions of 720x480 (NTSC) or 720x576 (PAL), exact frame rates (23.976, 25, or 29.97 fps), and a video bitrate not exceeding 9.8 Mbps. If your Y4M source already meets these specifications, the VOB output should import cleanly. Otherwise, you may need to add scaling and frame rate flags to the FFmpeg command.
Y4M is a video-only format and typically carries no audio stream. FFmpeg will not fail, but it will produce a VOB with no audio track since there is nothing to encode to AC3. This is valid for many DVD authoring workflows where audio is added separately. If you need audio in the output, you can add a separate audio source using an additional -i flag in the FFmpeg command alongside -map directives.
The -q:v flag controls MPEG-2 video quality using a scale from 1 (highest quality, largest file) to 31 (lowest quality, smallest file), with the default set to 4. For DVD authoring where quality is critical, lowering this value toward 1 or 2 will produce better visual fidelity at the cost of larger file sizes and higher bitrates. For example, replacing -q:v 4 with -q:v 2 in the command gives noticeably sharper MPEG-2 output, especially beneficial when the source Y4M contains high-detail or high-motion content.
Yes. The default AC3 audio bitrate of 192k is suitable for stereo audio, but DVD-Video supports AC3 at higher bitrates for better fidelity or surround sound. You can change -b:a 192k to values like -b:a 384k or -b:a 448k for higher-quality stereo or 5.1 surround. AC3 is the recommended codec for DVD compatibility, but you can also substitute -c:a libmp3lame for MP3 audio, though this is less universally supported by DVD players than AC3.
FFmpeg normally detects the output container format from the file extension, but VOB shares its internal structure so closely with MPEG-PS (Program Stream) that without the explicit -f vob flag, FFmpeg might default to the generic MPEG-PS muxer instead. The -f vob flag tells FFmpeg to use the specific VOB muxer, which enforces the correct packet formatting and stream constraints expected by DVD playback equipment and authoring tools. Omitting this flag could produce a file with a .vob extension that some DVD software refuses to parse correctly.
Technical Notes
Y4M (YUV4MPEG2) stores raw planar YUV frames — most commonly in 4:2:0 chroma subsampling — with a plain-text header per frame describing resolution, frame rate, and colorspace. Because there is no inter-frame compression or quantization, Y4M files are extremely large relative to their duration (a single minute of 1080p Y4M can exceed 10GB), making it impractical for delivery but ideal as a lossless intermediate. MPEG-2 video, the codec used in VOB, was specifically designed for the DVD-Video specification and operates efficiently on YUV 4:2:0 input — exactly what Y4M provides — so no colorspace conversion is needed during encoding. The VOB container supports multiple audio tracks and subtitle streams natively, but subtitle data cannot be sourced from Y4M (which supports no subtitle format), so subtitle streams would need to be added from a separate source. Chapters are not supported in raw VOB files — chapter metadata is stored in the DVD's IFO files, which are separate from VOB and must be generated by a DVD authoring application. One important consideration: DVD-Video defines strict constraints on video resolution and frame rate; if the Y4M source does not conform to standard DVD resolutions (720x480 at 29.97 fps for NTSC, or 720x576 at 25 fps for PAL), the resulting VOB may play correctly in software players like VLC but fail to import into strict DVD authoring tools without additional transcoding steps.