Array buffer allocation failed while trying to decode large files

[sorokinvj]

First of all, thanks for lib, it saved a lot efforts.

I have an AWS Lambda function that extracts peaks from audio files. Whenever I upload file to S3 this Lambda triggered and returns an array of numbers, which after I send to waveplasyer.js in my UI to draw waveform.

Everything works great for small files, but I stuck with large ones – duration about 1 hour, size like 200 Mb, Lambda either exceeds timeout, or get an error:

{
  "errorType": "RangeError",
  "errorMessage": "Array buffer allocation failed",
  "trace": [
    "RangeError: Array buffer allocation failed",
    "    at new ArrayBuffer (<anonymous>)",
    "    at new Float32Array (<anonymous>)",
    "    at Asset.<anonymous> (/var/task/node_modules/av/src/asset.js:118:15)",
    "    at Asset.cb (/var/task/node_modules/av/src/core/events.js:51:19)",
    "    at Asset.EventEmitter.emit (/var/task/node_modules/av/src/core/events.js:64:12)",
    "    at Class.<anonymous> (/var/task/node_modules/av/src/asset.js:202:24)",
    "    at Class.EventEmitter.emit (/var/task/node_modules/av/src/core/events.js:64:12)",
    "    at Class.Decoder.decode (/var/task/node_modules/av/src/decoder.js:90:14)",
    "    at M4ADemuxer.<anonymous> (/var/task/node_modules/av/src/decoder.js:54:26)",
    "    at M4ADemuxer.EventEmitter.emit (/var/task/node_modules/av/src/core/events.js:64:12)"
  ]
}

Could you guys help me with that please? I run out of ideas where to look and what to try to solve it.

This is my code:

// helper function to filter data
const filterData = audioBuffer => {
  const rawData = audioBuffer.getChannelData(0) // We only need to work with one channel of data
  const samples = 50 // Number of samples we want to have in our final data set
  const blockSize = Math.floor(rawData.length / samples) // the number of samples in each subdivision
  const filteredData = []
  for (let i = 0; i < samples; i++) {
    let blockStart = blockSize * i // the location of the first sample in the block
    let sum = 0
    for (let j = 0; j < blockSize; j++) {
      sum = sum + Math.abs(rawData[blockStart + j]) // find the sum of all the samples in the block
    }
    filteredData.push(sum / blockSize) // divide the sum by the block size to get the average
  }
  return filteredData
}

// helper for normalizing values
const normalizeData = filteredData => {
  const multiplier = Math.pow(Math.max(...filteredData), -1)
  return filteredData.map(n => n * multiplier)
}

// main function
async function getPeaks(fileBuffer) {
  console.log('>>>> starting decode...')
  const AudioContext = require('web-audio-api').AudioContext
  const context = new AudioContext()
  const peaksPromise = new Promise((resolve, reject) => {
    try {
      context.decodeAudioData(fileBuffer, audioBuffer => {
        const peaks = normalizeData(filterData(audioBuffer))
        console.log('>>>> finished decoding...', peaks)
        resolve(peaks)
      })
    } catch (error) {
      console.log('error on decoding', error)
      reject(error)
    }
  })
  return peaksPromise
}

module.exports = getPeaks

[anandarpit]

+1