birdgen/src/parseVolumeFrames.js

import exec from './exec.js'
import addExtraVideos from './addExtraVideos.js'
import getArgument from './getArgument.js'

const chaos = Math.max(Math.min(getArgument('chaos')??50, 100), 0)

function calculateAbsSum(arr) {
    return arr.reduce((total, current) => {
        return total + Math.abs(current)
    }, 0)
}

async function getVolumeFrames(inputPath) {
    const { stdout } = await exec(`audiowaveform --input-file "${inputPath}" --output-format json --output-file -`, {
        maxBuffer: 5 * 1024 * 1024
    })
    let info = JSON.parse(stdout)
    const range = info.bits==8?255:65535
    let finalArray = []
    let amount = 2 // because the array is of sample pairs
    let length = info.length / ((info.sample_rate / 1000) / info.samples_per_pixel)
    let perMs = length / info.length
    for (let i = 0; i < info.data.length; i+=amount) {
      finalArray.push(calculateAbsSum(info.data.slice(i, i+amount))/range*100)
    }
    return {
        perMs,
        average: calculateAbsSum(finalArray)/finalArray.length,
        length: finalArray.length,
        data: finalArray
    }
}

export default async function parseVolumeFrames(inputPath) {
    let info = await getVolumeFrames(inputPath)
    
    const indexToMs = i => i*info.perMs

    let sections = []

    let current = null
    let lastLoud = 0
    console.log(`Chaoticness set to ${chaos}%`)
    let maxLastLoud = 2*(150-chaos)
    let filter = info.average*1.2

    let duration = 0

    for (let i = 0; i < info.data.length; i ++) {
        if (i%500==0) {
            process.stdout.clearLine();
            process.stdout.cursorTo(0);
            process.stdout.write(`Parsing audio... ${Math.ceil(i/info.data.length*100)}%`)
        }
        let frame = info.data[i]
        let ms = indexToMs(i)
        if (frame>filter) {
            lastLoud = ms
            if (current) continue
            current = {
                start: Math.floor(ms)
            }
        } else {
            if (!current||(ms-lastLoud)<maxLastLoud) continue
            if (lastLoud-current.start>maxLastLoud) {
                current.end = Math.ceil(lastLoud)
                duration += current.end - current.start
                sections.push(current)
            }
            current = null
        }
    }
    console.log('')
    if (current) {
        current.end = Math.ceil(indexToMs(info.data.length))
        sections.push(current)
    }
    console.log(`Created ${sections.length} clips`)
    sections = await addExtraVideos(sections)
    return {
        duration: duration/1000,
        sections
    }
}