get-blob-duration/src/getBlobDuration.js

Convenience method to patch Chromium bug when getting duration of HTML5 video or audio Blob.

/**
 * @param {Blob|String} blob
 *
 * @returns {Promise<Number>} Blob duration in seconds.
 */
export default async function getBlobDuration(blob) {
  const tempVideoEl = document.createElement('video')

  const durationP = new Promise((resolve, reject) => {
    tempVideoEl.addEventListener('loadedmetadata', () => {
      // Chrome bug: https://bugs.chromium.org/p/chromium/issues/detail?id=642012
      if(tempVideoEl.duration === Infinity) {
        tempVideoEl.currentTime = Number.MAX_SAFE_INTEGER
        tempVideoEl.ontimeupdate = () => {
          tempVideoEl.ontimeupdate = null
          resolve(tempVideoEl.duration)
          tempVideoEl.currentTime = 0
        }
      }
      // Normal behavior
      else
        resolve(tempVideoEl.duration)
    })
    tempVideoEl.onerror = (event) => reject(event.target.error)
  })

  tempVideoEl.src = typeof blob === 'string' || blob instanceof String
    ? blob
    : window.URL.createObjectURL(blob)

  return durationP
}