∞ DDR

Infinite DDR

Type a song or paste a YouTube link. We pull the audio, find the beat, and write a Dance Dance Revolution style chart from Beginner to Challenge. Arrow keys, D F J K, or tap on a phone.

How it works

  1. 1Search a song or paste a YouTube link. The first time anyone plays a song its audio is fetched and cached, so it starts instantly for everyone after that; you can also upload an audio file.
  2. 2The beat analysis runs once per song on a server: spectral-flux onset detection, tempo by autocorrelation, a downbeat guess, and a 16th-note feature grid.
  3. 3A stepping model turns that into five charts, from quarter-note Beginner to 16th-note Challenge with jumps, freezes and crossovers, using DDR foot ratings.
  4. 4You play in the browser with keys or by tapping the panels on a phone, judged with DDR timing windows, scored out of 1,000,000, and posted to the song's world board.

Questions

▸Can I play Dance Dance Revolution in a browser with any song?

Yes. Infinite DDR (ddrinfinity.com) takes any YouTube song by name or link, pulls the audio, detects the beat and generates a DDR-style step chart at five difficulties, playable in the browser on a computer or phone. No download, no account.

▸How are the step charts made?

An onset detector finds drum and vocal hits, a tempo tracker locks the beat grid, and a two-foot stepping model places arrows on the song's groove: quarter notes at Beginner, 8ths at Difficult, 16th bursts, crossovers and jumps at Expert and Challenge. Charts are generated, not hand-stepped, and the same for every player so scores compare. A second generator trained on open StepMania simfile packs (Fraxtil, Club Fantastic) can be toggled.

▸What difficulties and foot ratings are there?

Beginner, Basic, Difficult, Expert and Challenge, rated in feet like the arcade (roughly 2 to 14) from notes per second, jumps and freezes.

▸How is scoring done?

DDR timing windows: Marvelous within 22.5 ms, Perfect 45 ms, Great 90 ms, Good 135 ms, Boo 180 ms, otherwise Miss. Jumps are judged as one row. Freeze arrows give O.K. or N.G. The money score is out of 1,000,000 and grades run AAA, AA+, AA, AA-, A+, A, A-, B, C, D, with E on a fail.

▸What are the controls?

Arrow keys or D F J K on a keyboard. On phones the four panels are a tappable DDR cross (or one row), with multi-touch for jumps. A sync calibration tool measures your audio latency. USB dance pad support is planned.

▸Does it work on iPhone and Android?

Yes, in the browser, and it can be added to the home screen as an app that launches full screen.

▸Is there a leaderboard?

Each song has a world board per difficulty, there is a global board of top plays, and the home page shows what people around the world are playing. Any song someone has played starts instantly for everyone.

▸How is it different from StepMania or ITGmania?

StepMania plays hand-stepped simfiles you install. Infinite DDR charts any song on the fly with no files, so it is a jukebox you can dance to rather than a simulator; its charts are not yet the quality of a good hand-stepped pack.

▸Does it cost anything?

No. It is free, with no ads and no account.