What AI mastering is
Mastering is the last step before a song goes out. It balances the tone, evens out the dynamics, sets the stereo image and brings the song to a loudness that streaming services accept. AI mastering is the name people give to doing that automatically. You drop in a finished mix, the software measures it, decides what to change and gives you a new file.
It takes seconds and costs little or nothing. What you get depends on the mix and on how the software decides what to do. This page explains the second part for OBRA.
What OBRA does to your song
OBRA Audio Mastering runs in your browser, so nothing is uploaded. It goes through six stages, and every move is written down with its number and its reason.
| Stage | What it does to your song |
|---|---|
| Listen | Measures tone in sixth-octave bands, dynamics band by band, stereo, phase and true peaks. |
| Tone | Compares your tone with how professional masters of its style sound, then evens it out with up to 8 EQ bands. Cuts come first. |
| Multiband | Four bands of gentle compression keep the lows, mids and highs steady from the first verse to the last chorus. |
| Glue and punch | A bus compressor glues the mix, a transient shaper brings the hits forward and tape or console saturation adds warmth. |
| Stereo | Opens the image above 140 Hz and keeps the bass in mono, so it still hits on phones and club systems. |
| Loudness | A clipper and a true-peak limiter reach the target level, measured in integrated LUFS (ITU-R BS.1770-4) on the file you download. |
You get three masters at the same loudness: Natural, OBRA and Loud. Switch between them while the song plays, and against your original at equal level, so that louder does not fool your ear. If you disagree with a move, change it in the Studio.
Is it really AI?
"AI mastering" is what most people type, so we use those words here. What OBRA does is automatic mastering. The engine measures your mix and decides each stage with rules and limits built from studying finished masters. No neural network decides your master.
We do use a neural network in one other place: splitting a song into stems (vocals, drums, bass and the rest) with Meta's Demucs model, which runs in your browser on a computer with WebGPU. Album and Vocal + beat use it to level the vocals, drums and bass across an album, or to rebalance a beat under your voice. The stem-based PRO master uses it too.
Automatic mastering is fast and consistent. It measures your mix, but it does not know what you meant by it.
AI mastering or a mastering engineer?
| Automatic mastering | A mastering engineer | |
|---|---|---|
| Time | Seconds | Hours to days |
| Cost | Free, or a few dollars a song | A fee per song or per project |
| Judgement | Measures your mix and applies rules | Listens with context and can talk to you |
| A mix with a problem | Cannot fix a bad balance | Can tell you what to fix and send the mix back |
For a demo, or a release you need today, automatic mastering can be all you need. For a record that matters a lot to you, a person adds judgement a program does not have. If you want both, OBRA ULTRA is mixing and mastering by an OBRA engineer: $19 / €19 / £19 per round, back within 72 hours (limited spots each week).
What is free and what costs money
| Plan | Price | What you get |
|---|---|---|
| Free | Free | 2 songs a day. All three masters, the Studio and every meter. WAV or FLAC up to 24-bit / 48 kHz. No account. |
| One song | $3 / €3 / £3 | Unlimited downloads of that song for 30 days. 88.2 / 96 kHz and 32-bit float. Reference master included. No account, no subscription. |
| OBRA PRO | $10 / €10 / £10 a month | Unlimited mastering and every tool. Vocal + beat mixes and albums. Your artist profile on OBRA. |
Listening is always free and complete. Vocal + beat ($5 / €5 / £5) and Album ($9 / €9 / £9) download per job, or come with OBRA PRO.
How to get a better result
- Export a WAV at 24-bit, not an MP3. A lossy file has already lost detail that mastering cannot bring back.
- Take the limiter off your master bus and leave peaks around −6 to −3 dBFS. The master does the final limiting.
- Fix the mix first. Mastering lifts a balanced mix. It cannot rescue a buried vocal or a kick that fights the bass.
- Compare at equal loudness. Louder always sounds better at first, so judge the master against your original at the same level.
- Choose the version for where the song goes. Natural stays close to the −14 LUFS that Spotify, YouTube and Tidal play at. OBRA and Loud are denser, for genres that want it.
- Check the result on headphones, on a phone and in a car before you release.
- If you have a song you want yours to sound like, use Reference mastering. It moves your master towards that track's tone, punch, width and loudness.
- Mixing vs mastering: what each step does and which problems belong to which
- LUFS for Spotify, Apple Music and YouTube: the loudness each platform plays at
- Reference mastering: master towards a song you love
Other online mastering services
We keep a dated page for each service, including where it is the better choice.
- LANDR alternative: a per-track price against two free songs a day
- eMastered alternative: preview free, pay to download
- BandLab Mastering alternative: free with an account and preset styles
- Free alternatives to LANDR and BandLab: the whole field in one guide
Frequently asked questions
What is AI mastering?
AI mastering is automatic mastering: software measures a finished mix, decides how to adjust the EQ, compression, stereo and loudness, and returns a mastered file in seconds. The name is used loosely. How much of it is machine learning depends on the service.
Is OBRA's mastering really AI?
It is automatic mastering that works like an engineer: it measures your mix, compares it with how professional masters of its style sound and decides the EQ, compression, stereo and limiting for your song. No neural network decides the master. A neural network is used only to split songs into stems, in the modes that work on stems: Album, Vocal + beat and the stem-based PRO master.
Is there free AI mastering with no sign-up?
Yes. OBRA gives two songs a day free, with no account, no card and no watermark: all three masters, the Studio and every meter, as a WAV or FLAC up to 24-bit / 48 kHz. Each extra song is a one-off $3 / €3 / £3, or unlimited with OBRA PRO ($10 / €10 / £10 a month). Listening is always free.
Is my song uploaded to a server?
No. The whole mastering engine runs in your browser, so your file never leaves your device and nothing is stored on our side.
Can AI mastering replace a mastering engineer?
For a demo or a release you need today, it can be enough. It does not replace judgement: an engineer can tell you the mix needs work, ask what you want and decide on taste. If a record matters a lot to you, consider a person, or OBRA ULTRA.
What loudness should I master to for Spotify and Apple Music?
Spotify, YouTube and Tidal play music at about −14 LUFS and turn louder masters down. Apple Music plays at about −16 LUFS. OBRA's Natural master stays close to that and keeps your dynamics. OBRA and Loud are denser.
Can I release a track mastered this way?
Yes. You keep every right you hold in your music. OBRA claims nothing and adds nothing to the file.