Free online USM to FLAC converter

USM files usually come from games and contain CRI Sofdec video with a multiplexed audio stream, while FLAC is an audio-only format. Converting them therefore requires extracting the audio from the USM container before encoding it as FLAC.

What the USM format is

USM is a proprietary CRI Middleware Sofdec container used for pre-rendered game videos, cutscenes, menus, and announcements. Games from publishers using CRIWARE commonly store these files with extensions such as .usm. A USM file can contain video plus ADX, HCA, or another CRI audio stream, so it is not normally a directly playable audio file.

What the FLAC format is

FLAC is a lossless audio codec. It reduces file size without discarding audio samples and supports metadata such as artist, album, and track number. FLAC is suitable for archiving or editing audio when the extracted source is already lossless; it does not restore quality lost in a compressed game soundtrack.

How to actually convert USM to FLAC

The reliable desktop workflow is to demultiplex the USM first, decode its audio stream, and then encode the resulting WAV as FLAC.

1. Make a backup of the original video.usm file. Work on a copy because extraction tools may create several intermediate files.
2. Use a USM-capable extractor such as USMTool, CriPakTools, or the USM extraction functions in VGMToolbox. Choose the tool's Extract, Demultiplex, or equivalent operation and select video.usm. The output may include an ADX, HCA, or WAV audio file.
3. If the extractor produces HCA or ADX, decode it with vgmstream or another decoder that supports the extracted codec. For example, a vgmstream build commonly uses:

vgmstream-cli -o extracted.wav extracted.hca

Replace extracted.hca with the actual output filename. If the extractor already produces extracted.wav, skip decoding.

4. Encode the decoded PCM audio as FLAC with FFmpeg:

ffmpeg -i extracted.wav -c:a flac -compression_level 5 output.flac

For multiple extracted files on a system with a shell loop, process each file separately and retain the original filenames. Do not pass the USM directly to FFmpeg unless your installed build explicitly reports USM demuxing support; many builds cannot read CRI Sofdec containers.

You can also try the free converter on 101convert.com without installing software. Because USM is usually a game video container rather than a standard audio container, an online converter may reject the file or require a USM-specific extraction step first.

Quality and compatibility limitations

FLAC preserves the decoded input exactly, but it cannot improve audio encoded originally as lossy ADX or HCA. If a USM contains several audio streams, such as dialogue and music, extraction may produce separate files; convert the required stream rather than the video file itself.

Check the extracted WAV's sample rate, channel count, and duration before encoding. A very short or silent result usually indicates that the wrong embedded stream was selected or that the USM uses a game-specific CRI variant unsupported by the extractor. Keep the original USM because FLAC contains only the selected audio and does not preserve the video, subtitles, or other streams.