audio/fn/insert.js

Audio loading, editing, and rendering for JavaScript

import { seg, planOffset } from '../plan.js'

function insertSegs(segs, at, len, ref) {
  let r = []
  for (let s of segs) {
    if (s[2] + s[1] <= at) r.push(s)
    else if (s[2] >= at) { let n = s.slice(); n[2] = s[2] + len; r.push(n) }
    else {
      let f = at - s[2], absR = Math.abs(s[3] || 1)
      r.push(seg(s[0], f, s[2], s[3], s[4]))
      r.push(seg(s[0] + f * absR, s[1] - f, at + len, s[3], s[4]))
    }
  }
  r.push(seg(0, len, at, undefined, ref ?? null))
  r.sort((a, b) => a[2] - b[2])
  return r
}

const insertPlan = (segs, ctx) => {
  let { total, sampleRate: sr, args } = ctx
  let source = args[0], off = planOffset(ctx.offset, total, total)
  // Normalize raw sources to audio instances for plan segment refs
  if (typeof source !== 'number' && !source?.pages) source = audio.from(source, { sampleRate: sr })
  let iLen = typeof source === 'number' ? Math.round(source * sr) : source.length
  if (ctx.length != null) iLen = Math.min(iLen, ctx.length)
  return insertSegs(segs, off, iLen, typeof source === 'number' ? null : source)
}

import audio from '../core.js'
audio.op('insert', { plan: insertPlan })