Free online VOB to ASF converter

What the VOB format is

VOB, or Video Object, is the MPEG program-stream container used on DVD-Video discs. A VOB can contain MPEG-2 video, AC-3 or MPEG audio, subtitles, navigation data, and multiple program streams. DVD authoring software, DVD recorders, and disc-copying tools create VOB files; they are commonly found in the VIDEO_TS folder with names such as VTS_01_1.VOB.

A feature-length DVD title is often split across several VOB files. Select the files belonging to the same title rather than converting menu or extras files. A VOB copied from a protected commercial DVD may still contain CSS encryption; ordinary conversion software does not remove that protection.

What the ASF format is

ASF, or Advanced Systems Format, is a Microsoft container designed for synchronized audio and video, streaming, and Windows Media files. It commonly stores WMV video and WMA audio and can carry metadata, timestamps, and streaming information.

ASF is useful when a legacy Windows application, media server, or device specifically requires an .asf file. It generally produces smaller files than DVD MPEG-2 at comparable viewing quality, but it is less suitable than modern MP4 for current phones, browsers, and editing applications.

How to actually convert VOB to ASF

Using FFmpeg

FFmpeg is a desktop command-line converter that can decode DVD MPEG-2 and encode ASF-compatible Windows Media codecs. Open a terminal in the folder containing the source file and run:

ffmpeg -i "input.vob" -c:v wmv2 -b:v 2500k -c:a wmav2 -b:a 128k "output.asf"

Replace the filenames and adjust -b:v to control video size and quality. A bitrate of 1500–2500 kbps is usually adequate for standard-definition DVD video; use a higher value when preserving more detail matters.

DVD video is frequently interlaced. For playback on progressive displays, add FFmpeg's deinterlacing filter:

ffmpeg -i "input.vob" -vf yadif -c:v wmv2 -b:v 2500k -c:a wmav2 -b:a 128k "output.asf"

For a file from a multi-part DVD title, process the complete title sequence with a DVD-aware ripper first, or create a lossless intermediate file, then pass that file to FFmpeg. Converting only VTS_01_1.VOB may omit later parts of the program.

Using the online converter

You can convert the file for free on the 101convert.com website without installing software: open the converter, select the VOB file, choose ASF as the output format, start the conversion, and download the resulting file. Uploading a file requires transferring its contents to the service, so use desktop FFmpeg for sensitive footage or very large DVD titles.

Quality and compatibility limitations

This conversion normally re-encodes MPEG-2 video and DVD audio into WMV2 and WMA, so it is not lossless. Increasing the output bitrate can reduce additional loss but cannot restore detail already absent from the source. Do not use -c copy unless the source streams are confirmed compatible with the ASF muxer and target player; DVD AC-3 audio and MPEG-2 video often have poorer compatibility than WMV/WMA.

ASF output does not preserve DVD menus, interactive navigation, disc structure, or reliably preserve subtitles and chapter behavior. Keep the original VOB files when those features or archival quality are required. Test the resulting ASF in the exact player or device that requires it, because support for ASF and individual WMV/WMA codecs varies among modern applications.