How to Make a Taiko no Tatsujin–Style TJA Chart

This guide shows how to turn an audio file into a .tja you can play in a simulator. Knowing what each step does helps you know what to adjust when something goes wrong.

1. Prepare the audio

Common formats like MP3, WAV, OGG, FLAC and M4A all work, and you can upload videos such as MP4/MKV directly—the audio track is extracted automatically. Limits: MP3/OGG/M4A 60 MB, WAV/FLAC 300 MB, video 600 MB.

If the intro is too long or there is a long silence at the end, trim it first with the Free Online Audio Trimmer and add fades—it all runs in your browser, nothing is uploaded and no credits are used. The compose page has the same trimmer when you upload a single file.

Only upload music you have the right to use; see the Terms of Service.

2. BPM and OFFSET

BPM (beats per minute) and OFFSET (when the first measure starts) are detected automatically. BPM snaps to nearby whole numbers, so a 150 BPM song is not read as 149.987.

If you already know the song’s exact BPM, enter it under Advanced parameters—that is noticeably more accurate than auto-detection.

For songs whose tempo changes, tick “Detect tempo changes in the song (BPMCHANGE)”. It is experimental and off by default: after you pick a file, the site first estimates how likely a tempo change is and suggests whether to tick it. On a steady-tempo song it can wrongly detect changes.

Already have a TJA for the same song? Upload it as the “Reference TJA” and its BPM, OFFSET, tempo changes, GOGO sections, DEMOSTART, title and lyrics are kept—only the notes are regenerated.

3. Choose difficulty and stars

Taiko difficulties from easiest to hardest are Easy, Normal, Hard and Oni, plus Ura Oni. Stars run 1–10; leave the field blank for automatic. When generating several difficulties at once, the default stars are Easy 3, Normal 4, Hard 5, Oni 8 and Ura Oni 9.

The free plan generates one difficulty per job; paid plans can generate all four difficulties in one click (or five including Ura Oni).

The engine defaults to AUTO, which picks one based on the song’s rhythmic complexity; for songs with tempo changes or busy rhythms you can choose Onset instead.

4. Generate, download, test, fix

1. Press “Start charting”; most songs finish in tens of seconds to a minute. If a job fails because of a problem on our side, the credit is refunded automatically.
2. Download the zip. The .tja and the audio file are in the same folder.
3. Play-test it on the Play TJA Charts Online page: when logged in you can pick your own generated charts without re-uploading, and drag to mark GOGO sections there too.
4. If something is off, click “Edit” on the job in your history and fix the notes in the chart editor.

5. Play it in a simulator

Put the .tja and audio in the same folder; the WAVE field must match the audio file name exactly, extension included. For example:

MySong/
  MySong.tja    ← WAVE:MySong.ogg
  MySong.ogg

Then put the whole folder into your simulator’s song directory (Taikojiro, TJAPlayer3 and OpenTaiko each have their own location—check their docs) and reload the song list.

TaikoForge outputs UTF-8. If the title shows up garbled in your simulator, see the encoding section of the TJA format guide.

Don’t want to install anything? Use the Play TJA Charts Online page. On a phone you can view charts and watch auto-play; playing yourself needs a physical keyboard.

Known limitations

• Tempo-change detection is still experimental: in songs that gradually speed up or slow down, or change tempo often, the BPM may be off and need entering by hand or fixing in the editor.
• In triplets, swing rhythms or sections not in 4/4, notes may land on a neighboring grid position, so play-test and fix as needed.
• TaikoForge does not generate branching charts (#BRANCHSTART); each difficulty is a single chart.
• Chart quality varies from song to song; AI-generated charts are not guaranteed to be accurate or to suit every player. Output is TJA only — osu!taiko is not supported.