Load an audio file and pick a target format from the list, which only shows what your browser supports. Press Convert, wait for the progress bar, then download the converted file.
WAV is written directly by this tool from the decoded samples, so it never depends on a codec. Compressed formats rely on the browser's MediaRecorder, and each browser ships a different set, so the tool asks your browser at runtime which ones it can actually produce.
No mainstream browser exposes an MP3 encoder, and adding one would mean loading a large third-party library. ToolsRift deliberately ships no external libraries, so WAV and the browser's own Opus-based formats are offered instead.
MediaRecorder encodes a live stream, so the audio has to be played through it in real time. A three minute song therefore takes about three minutes to encode, and the progress bar shows exactly where it has reached.