shared/core-utils/videos/bitrate.ts

   1 import { VideoResolution } from '@shared/models'
   2
   3 type BitPerPixel = { [ id in VideoResolution ]: number }
   4
   5 // https://bitmovin.com/video-bitrate-streaming-hls-dash/
   6
   7 const minLimitBitPerPixel: BitPerPixel = {
   8   [VideoResolution.H_NOVIDEO]: 0,
   9   [VideoResolution.H_144P]: 0.02,
  10   [VideoResolution.H_240P]: 0.02,
  11   [VideoResolution.H_360P]: 0.02,
  12   [VideoResolution.H_480P]: 0.02,
  13   [VideoResolution.H_720P]: 0.02,
  14   [VideoResolution.H_1080P]: 0.02,
  15   [VideoResolution.H_1440P]: 0.02,
  16   [VideoResolution.H_4K]: 0.02
  17 }
  18
  19 const averageBitPerPixel: BitPerPixel = {
  20   [VideoResolution.H_NOVIDEO]: 0,
  21   [VideoResolution.H_144P]: 0.19,
  22   [VideoResolution.H_240P]: 0.17,
  23   [VideoResolution.H_360P]: 0.15,
  24   [VideoResolution.H_480P]: 0.12,
  25   [VideoResolution.H_720P]: 0.11,
  26   [VideoResolution.H_1080P]: 0.10,
  27   [VideoResolution.H_1440P]: 0.09,
  28   [VideoResolution.H_4K]: 0.08
  29 }
  30
  31 const maxBitPerPixel: BitPerPixel = {
  32   [VideoResolution.H_NOVIDEO]: 0,
  33   [VideoResolution.H_144P]: 0.32,
  34   [VideoResolution.H_240P]: 0.29,
  35   [VideoResolution.H_360P]: 0.26,
  36   [VideoResolution.H_480P]: 0.22,
  37   [VideoResolution.H_720P]: 0.19,
  38   [VideoResolution.H_1080P]: 0.17,
  39   [VideoResolution.H_1440P]: 0.16,
  40   [VideoResolution.H_4K]: 0.14
  41 }
  42
  43 function getAverageTheoreticalBitrate (options: {
  44   resolution: VideoResolution
  45   ratio: number
  46   fps: number
  47 }) {
  48   const targetBitrate = calculateBitrate({ ...options, bitPerPixel: averageBitPerPixel })
  49   if (!targetBitrate) return 192 * 1000
  50
  51   return targetBitrate
  52 }
  53
  54 function getMaxTheoreticalBitrate (options: {
  55   resolution: VideoResolution
  56   ratio: number
  57   fps: number
  58 }) {
  59   const targetBitrate = calculateBitrate({ ...options, bitPerPixel: maxBitPerPixel })
  60   if (!targetBitrate) return 256 * 1000
  61
  62   return targetBitrate
  63 }
  64
  65 function getMinTheoreticalBitrate (options: {
  66   resolution: VideoResolution
  67   ratio: number
  68   fps: number
  69 }) {
  70   const minLimitBitrate = calculateBitrate({ ...options, bitPerPixel: minLimitBitPerPixel })
  71   if (!minLimitBitrate) return 10 * 1000
  72
  73   return minLimitBitrate
  74 }
  75
  76 // ---------------------------------------------------------------------------
  77
  78 export {
  79   getAverageTheoreticalBitrate,
  80   getMaxTheoreticalBitrate,
  81   getMinTheoreticalBitrate
  82 }
  83
  84 // ---------------------------------------------------------------------------
  85
  86 function calculateBitrate (options: {
  87   bitPerPixel: BitPerPixel
  88   resolution: VideoResolution
  89   ratio: number
  90   fps: number
  91 }) {
  92   const { bitPerPixel, resolution, ratio, fps } = options
  93
  94   const resolutionsOrder = [
  95     VideoResolution.H_4K,
  96     VideoResolution.H_1440P,
  97     VideoResolution.H_1080P,
  98     VideoResolution.H_720P,
  99     VideoResolution.H_480P,
 100     VideoResolution.H_360P,
 101     VideoResolution.H_240P,
 102     VideoResolution.H_144P,
 103     VideoResolution.H_NOVIDEO
 104   ]
 105
 106   for (const toTestResolution of resolutionsOrder) {
 107     if (toTestResolution <= resolution) {
 108       return Math.floor(resolution * resolution * ratio * fps * bitPerPixel[toTestResolution])
 109     }
 110   }
 111
 112   throw new Error('Unknown resolution ' + resolution)
 113 }