Free online ULT to AAC converter

1. Source format: ULT

ULT is a tracker music module format associated with UltraTracker, a DOS-era music sequencer used by hobbyist composers and demoscene creators. Instead of storing a finished audio recording, an ULT file contains pattern data, instrument definitions, and sample references that a compatible player uses to synthesize the song. ULT files are typically used for retro game music, demo scene tracks, and archived tracker compositions.

2. Target format: AAC

AAC (Advanced Audio Coding) is a modern compressed audio format designed to deliver good sound quality at relatively low file sizes. It is widely supported by phones, media players, streaming platforms, and editing software. Compared with tracker modules, AAC is a finished audio format: it stores the rendered sound, not the musical instructions. That makes it convenient for playback on almost any device and for sharing as a standard audio file.

3. How to perform the conversion

Because ULT is a module format, the conversion must first render the tracker song to audio, then encode that audio to AAC. The most reliable workflow is to use a tracker player or converter that can open ULT files and export WAV or another uncompressed audio format, then convert that output to AAC.

Step 1: Open the ULT file in software that supports tracker modules, such as OpenMPT, XMPlay with the appropriate plugin, or another tracker-capable player/converter.

Step 2: Render or export the song to WAV or another lossless audio format. In OpenMPT, this is typically done through File → Export → Wave or a similar render option, depending on the version.

Step 3: Convert the rendered audio to AAC using an audio encoder such as FFmpeg. For example, if you exported song.wav, you can create an AAC file with:

ffmpeg -i song.wav -c:a aac -b:a 192k song.aac

Step 4: If your player or editor prefers AAC inside an M4A container, you can instead output song.m4a with the same AAC audio stream:

ffmpeg -i song.wav -c:a aac -b:a 192k song.m4a

Step 5: Listen to the result and, if needed, adjust the bitrate. Common choices are 128k, 192k, or 256k, depending on the desired balance between quality and file size.

If you want a simple browser-based workflow, you can convert the file on 101convert.com for free without installing any software.

4. Notes on quality, compatibility, or limitations

ULT to AAC is not a direct format-to-format conversion in the same way as changing one audio codec to another. ULT must be played back and rendered first, so the final AAC file depends on the player’s interpretation of the module, including effects, mixing, and sample handling.

Because AAC is lossy, some detail from the rendered audio will be discarded during encoding. To preserve the best quality, export the ULT file to a lossless intermediate such as WAV before encoding. Also note that tracker modules may sound slightly different across players if they do not implement the format identically, so using a well-tested tracker renderer is important for consistent results.

Finally, ULT files are often short and loop-based, so if you are converting for archival purposes, keep the original ULT file as well as the AAC version. The AAC file is ideal for playback and sharing, while the ULT preserves the editable tracker composition.