Spec reference

লয় — tempo tiers

A row may carry lay: "drut" | "madhya" | "vilambit", which holds until another row changes it. meta.bpm is the দ্রুত (fast) tempo; the other two play at a fraction of it — 0.75 and 0.5 by default. Override per document with meta.laySpeeds, or per call with the player's / exporter's laySpeeds option. A document with no lay anywhere plays exactly as it did before the field existed.

{ "meta": { "bpm": 120, "laySpeeds": { "vilambit": 0.4 } },
  "parts": [ { "rows": [
    { "lay": "vilambit", "notes": [ … ] },   // this row on, at 0.4 × 120
    { "notes": [ … ] },                      // still বিলম্বিত
    { "lay": "drut", "notes": [ … ] }        // back to 120
  ] } ] }

The player changes the tabla with it: tabla-js plays each stretch from single bols at its own tempo, so the drum never drifts against the melody.

তালফেরতা — changing taal

A row may also carry taal (same shape as meta.taal) and an optional printed taalName. It holds until another row changes it; meta.taal is the opening taal. taal: null switches to মুক্তছন্দ (the accompaniment rests). It is independent of lay: a row may change either, both or neither.

{ "meta": { "taal": { "id": "dadra", "numBeats": 6, "bhaags": [3, 3] } },
  "parts": [ { "rows": [
    { "notes": [ … ] },                                              // দাদরা
    { "taal": { "id": "shashthi", "numBeats": 6, "bhaags": [2, 4] },
      "taalName": "ষষ্ঠী", "lay": "drut", "notes": [ … ] },         // ষষ্ঠী, দ্রুত
    { "taal": { "id": "kehrwa", "numBeats": 8, "bhaags": [4, 4] },
      "notes": [ … ] }                                               // কাহারবা, still দ্রুত
  ] } ] }

The viewer prints the change as a centred line between systems, as স্বরবিতান does; the player swaps the theka (or click, drum pattern) on that row, and the staff view changes its time signature there.

Tabla

All optional, all player-only. taal.variation picks a tabla-js variation by name (any case); omitted, the taal plays its default. A taal may also carry its own tabla — a theka of one cell per matra, with fillerLight, fillerBusy, tihai + tihaiArrival and bols — in tabla-js's swaralipi-taal shape; every section must be whole cycles. A custom taal is any id not in the catalogue, with its own cycle; without a theka it plays a catalogue taal of the same vibhags and khaali, else a plain theka on its vibhags. Its bhaags, sam and khaali count from where its lines open: a sam on another vibhag means each line opens before sam. Its theka is written from sam. meta.fillers is auto (default), light, busy or off; meta.tihai: true closes the song with a tihai on its last সম.

{ "meta": { "taal": { "id": "kehrwa", "numBeats": 8, "variation": "Kaharwa 2" },
            "fillers": "light", "tihai": true } }

{ "meta": { "taal": { "id": "mine", "numBeats": 4, "bhaags": [2, 2],
            "theka": ["dha ge", "na", "ta ke", "na"], "tihaiArrival": "dha" } } }

Compressed rows

Every row shares one set of columns, so a row with extra notes widens every line. "compress": true on that row squeezes it into the line's width instead. Its notes then no longer sit under the columns above. Display only; a row that already fits is unchanged. "flush": true aligns a row left, leaving the opening bar's column clear; display only.

Example

{ "svara": ["madhyam", "m"], "lyric": "অ" }      // pitch + lyric
{ "svara": ["madhyam", "p"], "komal": true }     // flat
{ "sustain": true, "lyric": "৹" }                // আ-কার hold
{ "bar": "single" }                              // দাঁড়ি

Worked examples: akarone, octaves, microtones, matra, brackets. Full schema: src/spec/schema.ts.