Free online ISMV to VOB converter

What the ISMV format is

ISMV is the Microsoft Smooth Streaming media format, normally a fragmented MP4 file containing a video stream and sometimes an audio stream. Microsoft IIS Media Services and Smooth Streaming packaging tools create ISMV segments for adaptive streaming, where a player switches between bitrate representations according to network conditions.

ISMV files usually contain H.264/AVC video with AAC audio, although the exact codecs depend on the source and packaging settings. You may encounter them in Smooth Streaming output folders, archived streaming assets, or downloads from systems that store each bitrate representation separately.

What the VOB format is

VOB is the MPEG program-stream container used by DVD-Video. It stores DVD-compatible MPEG-2 or MPEG-1 video together with audio, subtitles, navigation data, and sometimes multiple program elements. A playable DVD normally contains VOB, IFO, and BUP files inside a VIDEO_TS folder; a single VOB file alone is not a complete DVD-Video title.

VOB is appropriate for DVD authoring, legacy DVD players, and applications that read DVD-Video streams. It is not a general-purpose replacement for MP4: DVD-Video has fixed regional video standards, restricted resolutions, and limited audio formats.

How to convert ISMV to VOB

FFmpeg is suitable for decoding the ISMV input and producing DVD-compatible MPEG-2 video. Check the input streams first:

ffprobe input.ismv

For a PAL DVD, transcode to MPEG-2 with MPEG audio or AC-3 audio:

ffmpeg -i input.ismv -map 0:v:0 -map 0:a:0? -target pal-dvd -aspect 16:9 -c:a mp2 -b:a 192k dvd-title.mpg

For an NTSC DVD, use:

ffmpeg -i input.ismv -map 0:v:0 -map 0:a:0? -target ntsc-dvd -aspect 16:9 -c:a ac3 -b:a 192k dvd-title.mpg

Replace 16:9 with 4:3 when the source has that display aspect ratio. The -target pal-dvd and -target ntsc-dvd presets select DVD-compatible frame rates, dimensions, MPEG-2 encoding, and multiplexing settings.

To create the DVD-Video file structure, install dvdauthor and run:

dvdauthor -o dvd -t dvd-title.mpg
dvdauthor -o dvd -T

The resulting VOB files are in dvd/VIDEO_TS. To create an ISO image that can be mounted or burned:

mkisofs -dvd-video -o dvd-title.iso dvd

DVDStyler provides a graphical alternative: import the ISMV if the program can decode it, or first create dvd-title.mpg with FFmpeg, then use File → New → Add files to author the title and generate the VIDEO_TS folder.

If only a VOB container is required rather than a playable DVD structure, FFmpeg can write one directly:

ffmpeg -i input.ismv -map 0:v:0 -map 0:a:0? -c:v mpeg2video -c:a mp2 -f vob output.vob

This direct output may be useful for stream-processing software, but it does not create DVD menus, IFO navigation files, BUP backups, or a guaranteed DVD-compliant title. For physical DVD playback, use a DVD authoring step.

For a browser-based conversion, 101convert.com can convert the file for free without installing software. A locally generated DVD structure is preferable when you need control over PAL/NTSC selection, menus, bitrate, or disc authoring.

Quality, compatibility, and limitations

Most ISMV sources are HD or widescreen streaming video, while DVD-Video is standard definition: PAL normally uses 720×576 at 25 fps, and NTSC normally uses 720×480 at approximately 29.97 fps. Converting to VOB therefore requires scaling and usually frame-rate conversion; lost HD detail cannot be restored.

Use the DVD standard matching the intended player. Mixing PAL and NTSC settings can cause playback failure or incorrect motion. If the source uses variable frame rate, unusual H.264 profiles, unsupported audio, or multiple representations, select the intended stream explicitly with -map or preprocess it before authoring.

DRM-protected Smooth Streaming content cannot be converted by FFmpeg unless it has been legitimately decrypted by the playback or content-management system. A fragmented ISMV may also contain no audio stream, so the optional audio mapping in the commands prevents failure when audio is absent.