MusicGen weights are CC-BY-NC: commercial video music on Sume

MusicGen's code is MIT-licensed but its model weights are CC-BY-NC 4.0, so the weights are not licensed for commercial use. For a brand video or an ad, that is the first thing to settle, and it is the reason many teams use a hosted music route instead. Sume's Music Router runs Lyria 3.5 and returns an audio file for a fixed per-generation price.

The license facts come from Meta's AudioCraft repository, read on 2026-10-02. This is a licensing question, not legal advice; read the license text and talk to a lawyer for anything high stakes.

What does the AudioCraft repository say about licenses?

The repository describes MusicGen as a state-of-the-art controllable text-to-music model with textual and melodic conditioning. It states the code is under the MIT license and the model weights are under CC-BY-NC 4.0. The page I read refers to a separate MUSICGEN.md file for maximum duration, sample rate and conditioning parameters, and that file was not part of what I fetched, so this post makes no claims about them.

CC-BY-NC means attribution is required and commercial use is not permitted. A paid client video, a monetized channel or an ad all raise the question. Publishing a hobby project with credit is a different case from a campaign.

What does a hosted route change?

A hosted route replaces a weights license with a service agreement and a per-job price. On Sume, POST /v1/music-router/generate takes a prompt and optionally an image, and returns a Sume-hosted audio artifact. The catalog price is $0.125 per generation for every Music Router model.

That does not make every use automatically safe. You still need to read the terms that apply to your account, and you may need to label AI-generated music on some platforms.

How do you generate a bed for a video?

Describe tempo, key, instruments and an arc, and say instrumental. Sume has no duration parameter, so put the length in the prompt.

curl -X POST https://api.sume.com/v1/music-router/generate \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: score-001" \
  -d '{
    "model": "sume/music-auto",
    "prompt": "[0:00-0:15] Intro: warm lo-fi hip hop, 84 BPM, C minor, dusty Rhodes. [0:15-0:45] Groove: brushed boom-bap drums, muted trumpet answer. A 45-second track. Instrumental, no vocals."
  }'

Then fetch the finished audio:

curl https://api.sume.com/v1/jobs/$JOB_ID/status \
  -H "Authorization: Bearer $SUME_API_KEY"

curl https://api.sume.com/v1/jobs/$JOB_ID/result \
  -H "Authorization: Bearer $SUME_API_KEY"

What should a commercial checklist include?

Run the same checks whatever engine you use.

• Read the license for the weights or the terms of service, not the code license.
• Keep the prompt, the model id, the job id and the date with every track.
• Check each platform's rules for AI-generated audio and for labels.
• Do not prompt for a named artist's voice or copyrighted lyrics.
• Listen to the whole track. Keep the take you approve rather than assuming a re-run will match it.

Where does MusicGen still make sense?

For research, personal projects and prototypes with attribution, an open model with melody conditioning is a good way to learn what a prompt does. Keep the output out of paid work unless you have a license that allows it. When a track is for a client, generate it on a service whose terms you can read and file.

If you already have MusicGen audio in a project, find out where it is used. Anything that was published commercially deserves a review now, not at the next client audit. Replacing a bed is cheap: one new generation costs $0.125 on the Music Router, and a Timeline soundtrack swap is a one-field change in the render request.