/**
 * @param silencePointPercent (float) Percent into duration to set the point
 */
function silencePoints(silenceRanges, silencePointPercent) {
    let silencePoints = []
    for (let i = 0; i < silenceRanges.length; i++) {
        let range = silenceRanges[i];
        let point = range[0] + range[1] * silencePointPercent
        silencePoints.push(point)
    }
    return silencePoints
}

/**
 * Input: PCM data list
 * Output: List of [silence start offset (sec), duration (sec)]
 */
function silenceRanges(pcmData, sampleRate) {
    const silenceThreshold = .1

	let silenceStartIndex = -1
	let silenceRanges = []
	for (let i = 0; i <= pcmData.length; i++) {
		let pcmVal = (i < pcmData.length ? pcmData[i] : silenceThreshold)
		if (pcmVal < silenceThreshold) {
			if (silenceStartIndex === -1) {
				silenceStartIndex = i
			}
		} else { // pcmVal >= silenceThreshold
			if (silenceStartIndex !== -1) {
				silenceStartOffset = silenceStartIndex / sampleRate
				silenceDurationIndexCount = i - silenceStartIndex
				silenceDuration = silenceDurationIndexCount / sampleRate
				silenceRanges.push([silenceStartOffset, silenceDuration])
				silenceStartIndex = -1
			}
		}
	}
	return silenceRanges
}

const input = [
    0.1, 0.1, 0.1, 0.1, 0.1,
    0, 0, 0, 0, 0,
    0.1, 0.1, 0.1, 0.1, 0.1,
    0, 0, 0, 0, 0,
    0, 0, 0, 0, 0,
    0.1, 0.1, 0.1, 0.1, 0.1,
    0.1, 0.1, 0.1, 0.1, 0.1,
    0.1, 0.1, 0.1, 0.1, 0.1,
    0, 0, 0, 0, 0,
    0, 0, 0, 0, 0,
]

let ranges = silenceRanges(input, 1)
let points = silencePoints(ranges, .5)
console.log(`ranges:`, ranges)
console.log(`points:`, points)