Free online ISMV to TS converter

A TS file is commonly required by broadcast tools, MPEG-TS playback hardware, media servers, and editors that do not accept fragmented MP4. Converting an ISMV file can also make archived Smooth Streaming video easier to inspect and remux.

What the ISMV format is

ISMV is a fragmented MP4 container used by Microsoft IIS Smooth Streaming. Smooth Streaming packages usually contain video fragments with the .ismv extension, audio fragments with .isma, and a manifest such as .ismc.

The video may use H.264/AVC, VC-1, or another codec supported by the original streaming workflow. ISMV files are created by Smooth Streaming encoders, publishing systems, and recording or packaging software; they are often encountered after extracting content from an IIS Smooth Streaming archive. A single fragment may not represent a complete program, and DRM-protected files cannot be converted normally without authorized decryption.

What the TS format is

TS, or MPEG transport stream, stores packetized audio and video for broadcast transmission, IPTV, set-top boxes, cameras, and many media servers. It is less dependent on a conventional file index than MP4, so players can begin decoding at packet boundaries and recover more easily from transmission errors.

TS is a useful target when the receiving application requires MPEG-TS or when H.264 video must be carried in an Annex B transport stream. It can contain multiple programs and streams, but some applications expect a specific codec, program layout, or constant packet size.

How to convert ISMV to TS

FFmpeg is the most practical desktop method because it can read fragmented MP4 and write an MPEG transport stream without changing the media when the codecs are compatible.

1. Install FFmpeg and place the source file in a working folder.
2. Open a terminal in that folder.
3. Run this stream-copy command:

ffmpeg -i input.ismv -map 0 -c copy output.ts

-map 0 preserves all detected streams, while -c copy remuxes them without re-encoding. Replace input.ismv and output.ts with the actual filenames.

For an H.264 source, explicitly converting MP4-style H.264 length prefixes to the Annex B format expected by many TS devices can help:

ffmpeg -i input.ismv -map 0 -c copy -bsf:v h264_mp4toannexb output.ts

If the source contains unsupported codecs, timestamp problems, or damaged fragments, re-encode instead:

ffmpeg -i input.ismv -map 0:v:0 -map 0:a? -c:v libx264 -preset medium -crf 18 -c:a aac -b:a 192k -f mpegts output.ts

This second command changes the media and therefore takes longer and may reduce quality. If an ISMV package includes several sequential video fragments, concatenate them with FFmpeg's concat demuxer rather than treating each fragment as a complete movie. Create files.txt containing lines such as file 'fragment001.ismv', then run:

ffmpeg -f concat -safe 0 -i files.txt -c copy output.ts

Use the files in playback order and verify that their codecs, stream layouts, and time bases match. If you prefer not to install software, the conversion can be performed for free on the 101convert.com website; upload only files you are permitted to process and download the resulting TS file after conversion.

Quality and compatibility limits

Stream copying does not alter the encoded audio or video, but TS may be larger than the original ISMV because the containers use different packet overhead and indexing. Converting the container does not improve resolution, bitrate, or codec quality.

Check the result with ffprobe output.ts. A device may still reject the file if it requires MPEG-2 video, a particular audio codec, 188-byte packets, a fixed program identifier, or constant bitrate. Re-encode or adjust the muxer settings only when the target specification requires it.