Free online USM to ASF converter

What the USM format is

USM is a video container developed by CRI Middleware for the Sofdec playback system. It is common in video game assets, including opening movies, cutscenes, menus, and other pre-rendered footage. Game publishers and developers create USM files with CRI tools; players normally access them through the game engine rather than a general-purpose media player.

USM files can contain video and audio streams, and some are encrypted or use game-specific protection. The extension alone does not reveal the codec, encryption state, or whether a particular extractor can process the file. Renaming video.usm to video.asf does not convert it.

What the ASF format is

ASF, or Advanced Systems Format, is a Microsoft container designed for streaming and storing synchronized audio and video. It is associated with Windows Media codecs such as WMV and WMA and uses the .asf extension; some ASF files use .wmv or .wma instead.

ASF is useful when a legacy Windows application, media server, or hardware player specifically expects a Windows Media container. It can provide indexed playback, metadata, streaming-oriented packetization, and support for WMV/WMA compression. ASF is not a universal replacement for USM features: proprietary game metadata, encryption, unusual audio tracks, subtitles, and interactive playback behavior generally cannot be preserved.

How to actually convert USM to ASF

The simplest option is the free converter on 101convert.com. Upload the USM file, choose ASF as the output format, start the conversion, and download the resulting file when processing finishes. This works only when the converter supports that particular USM variant; encrypted or damaged game assets may be rejected.

For local processing, use a USM extractor or decoder that explicitly supports the game’s CRI/Sofdec variant. Community utilities are often version-specific, so identify the game and check the utility’s documentation before processing a batch.

1. Make a copy of the original USM file. Do not modify the game’s installed asset.
2. Run the compatible USM extraction or decryption tool and export the contained video and audio. The output may be a standard video file, a raw MPEG stream, or separate audio files.
3. Test the extracted result in a player such as VLC. If the extraction produces separate streams, combine them only after confirming their duration and synchronization.
4. Encode the playable result to ASF with FFmpeg. For a broadly compatible Windows Media output, use WMV video and WMA audio:

ffmpeg -i extracted.mkv -c:v wmv2 -b:v 2M -c:a wmav2 -b:a 128k output.asf

Adjust -b:v to the source resolution and desired size. Use -an if the source has no usable audio. If the extractor produces a file that FFmpeg cannot read, transcode it first with a media application that supports its actual codec, then use the resulting standard file as the FFmpeg input.

Check the output with ffprobe output.asf or a compatible media player. A successful file should report an ASF container and playable video and audio streams.

Quality, compatibility, and limitations

USM-to-ASF conversion is normally a transcoding operation, so WMV encoding can reduce detail compared with the original stream. Choose a higher video bitrate for small text, fast motion, or animation; increasing the bitrate cannot restore detail already lost during USM extraction.

ASF compatibility depends more on the codecs inside the container than on the .asf extension. WMV2 video with WMA2 audio is more suitable for older Windows software than newer codecs, but some modern players may support ASF only partially. Verify frame rate, aspect ratio, audio synchronization, and seeking after conversion.

Encrypted USM files may be playable only by the original game and may not be legally or technically convertible without an authorized decryption method. Do not distribute extracted game assets unless the applicable license permits it.