server/lib/video-transcoding-profiles.ts

   1 import { logger } from '@server/helpers/logger'
   2 import { AvailableEncoders, EncoderOptionsBuilder, getTargetBitrate, VideoResolution } from '../../shared/models/videos'
   3 import { buildStreamSuffix, resetSupportedEncoders } from '../helpers/ffmpeg-utils'
   4 import {
   5   canDoQuickAudioTranscode,
   6   ffprobePromise,
   7   getAudioStream,
   8   getMaxAudioBitrate,
   9   getVideoFileBitrate,
  10   getVideoStreamFromFile
  11 } from '../helpers/ffprobe-utils'
  12 import { VIDEO_TRANSCODING_FPS } from '../initializers/constants'
  13
  14 /**
  15  *
  16  * Available encoders and profiles for the transcoding jobs
  17  * These functions are used by ffmpeg-utils that will get the encoders and options depending on the chosen profile
  18  *
  19  */
  20
  21 // Resources:
  22 //  * https://slhck.info/video/2017/03/01/rate-control.html
  23 //  * https://trac.ffmpeg.org/wiki/Limiting%20the%20output%20bitrate
  24
  25 const defaultX264VODOptionsBuilder: EncoderOptionsBuilder = async ({ input, resolution, fps }) => {
  26   const targetBitrate = await buildTargetBitrate({ input, resolution, fps })
  27   if (!targetBitrate) return { outputOptions: [ ] }
  28
  29   return {
  30     outputOptions: [
  31       `-r ${fps}`,
  32       `-maxrate ${targetBitrate}`,
  33       `-bufsize ${targetBitrate * 2}`
  34     ]
  35   }
  36 }
  37
  38 const defaultX264LiveOptionsBuilder: EncoderOptionsBuilder = async ({ resolution, fps, streamNum }) => {
  39   const targetBitrate = getTargetBitrate(resolution, fps, VIDEO_TRANSCODING_FPS)
  40
  41   return {
  42     outputOptions: [
  43       `${buildStreamSuffix('-r:v', streamNum)} ${fps}`,
  44       `${buildStreamSuffix('-b:v', streamNum)} ${targetBitrate}`,
  45       `-maxrate ${targetBitrate}`,
  46       `-bufsize ${targetBitrate * 2}`
  47     ]
  48   }
  49 }
  50
  51 const defaultAACOptionsBuilder: EncoderOptionsBuilder = async ({ input, streamNum }) => {
  52   const probe = await ffprobePromise(input)
  53
  54   if (await canDoQuickAudioTranscode(input, probe)) {
  55     logger.debug('Copy audio stream %s by AAC encoder.', input)
  56     return { copy: true, outputOptions: [] }
  57   }
  58
  59   const parsedAudio = await getAudioStream(input, probe)
  60
  61   // We try to reduce the ceiling bitrate by making rough matches of bitrates
  62   // Of course this is far from perfect, but it might save some space in the end
  63
  64   const audioCodecName = parsedAudio.audioStream['codec_name']
  65
  66   const bitrate = getMaxAudioBitrate(audioCodecName, parsedAudio.bitrate)
  67
  68   logger.debug('Calculating audio bitrate of %s by AAC encoder.', input, { bitrate: parsedAudio.bitrate, audioCodecName })
  69
  70   if (bitrate !== undefined && bitrate !== -1) {
  71     return { outputOptions: [ buildStreamSuffix('-b:a', streamNum), bitrate + 'k' ] }
  72   }
  73
  74   return { outputOptions: [ ] }
  75 }
  76
  77 const defaultLibFDKAACVODOptionsBuilder: EncoderOptionsBuilder = ({ streamNum }) => {
  78   return { outputOptions: [ buildStreamSuffix('-q:a', streamNum), '5' ] }
  79 }
  80
  81 // Used to get and update available encoders
  82 class VideoTranscodingProfilesManager {
  83   private static instance: VideoTranscodingProfilesManager
  84
  85   // 1 === less priority
  86   private readonly encodersPriorities = {
  87     vod: this.buildDefaultEncodersPriorities(),
  88     live: this.buildDefaultEncodersPriorities()
  89   }
  90
  91   private readonly availableEncoders = {
  92     vod: {
  93       libx264: {
  94         default: defaultX264VODOptionsBuilder
  95       },
  96       aac: {
  97         default: defaultAACOptionsBuilder
  98       },
  99       libfdk_aac: {
 100         default: defaultLibFDKAACVODOptionsBuilder
 101       }
 102     },
 103     live: {
 104       libx264: {
 105         default: defaultX264LiveOptionsBuilder
 106       },
 107       aac: {
 108         default: defaultAACOptionsBuilder
 109       }
 110     }
 111   }
 112
 113   private availableProfiles = {
 114     vod: [] as string[],
 115     live: [] as string[]
 116   }
 117
 118   private constructor () {
 119     this.buildAvailableProfiles()
 120   }
 121
 122   getAvailableEncoders (): AvailableEncoders {
 123     return {
 124       available: this.availableEncoders,
 125       encodersToTry: {
 126         vod: {
 127           video: this.getEncodersByPriority('vod', 'video'),
 128           audio: this.getEncodersByPriority('vod', 'audio')
 129         },
 130         live: {
 131           video: this.getEncodersByPriority('live', 'video'),
 132           audio: this.getEncodersByPriority('live', 'audio')
 133         }
 134       }
 135     }
 136   }
 137
 138   getAvailableProfiles (type: 'vod' | 'live') {
 139     return this.availableProfiles[type]
 140   }
 141
 142   addProfile (options: {
 143     type: 'vod' | 'live'
 144     encoder: string
 145     profile: string
 146     builder: EncoderOptionsBuilder
 147   }) {
 148     const { type, encoder, profile, builder } = options
 149
 150     const encoders = this.availableEncoders[type]
 151
 152     if (!encoders[encoder]) encoders[encoder] = {}
 153     encoders[encoder][profile] = builder
 154
 155     this.buildAvailableProfiles()
 156   }
 157
 158   removeProfile (options: {
 159     type: 'vod' | 'live'
 160     encoder: string
 161     profile: string
 162   }) {
 163     const { type, encoder, profile } = options
 164
 165     delete this.availableEncoders[type][encoder][profile]
 166     this.buildAvailableProfiles()
 167   }
 168
 169   addEncoderPriority (type: 'vod' | 'live', streamType: 'audio' | 'video', encoder: string, priority: number) {
 170     this.encodersPriorities[type][streamType].push({ name: encoder, priority })
 171
 172     resetSupportedEncoders()
 173   }
 174
 175   removeEncoderPriority (type: 'vod' | 'live', streamType: 'audio' | 'video', encoder: string, priority: number) {
 176     this.encodersPriorities[type][streamType] = this.encodersPriorities[type][streamType]
 177                                                     .filter(o => o.name !== encoder && o.priority !== priority)
 178
 179     resetSupportedEncoders()
 180   }
 181
 182   private getEncodersByPriority (type: 'vod' | 'live', streamType: 'audio' | 'video') {
 183     return this.encodersPriorities[type][streamType]
 184       .sort((e1, e2) => {
 185         if (e1.priority > e2.priority) return -1
 186         else if (e1.priority === e2.priority) return 0
 187
 188         return 1
 189       })
 190       .map(e => e.name)
 191   }
 192
 193   private buildAvailableProfiles () {
 194     for (const type of [ 'vod', 'live' ]) {
 195       const result = new Set()
 196
 197       const encoders = this.availableEncoders[type]
 198
 199       for (const encoderName of Object.keys(encoders)) {
 200         for (const profile of Object.keys(encoders[encoderName])) {
 201           result.add(profile)
 202         }
 203       }
 204
 205       this.availableProfiles[type] = Array.from(result)
 206     }
 207
 208     logger.debug('Available transcoding profiles built.', { availableProfiles: this.availableProfiles })
 209   }
 210
 211   private buildDefaultEncodersPriorities () {
 212     return {
 213       video: [
 214         { name: 'libx264', priority: 100 }
 215       ],
 216
 217       // Try the first one, if not available try the second one etc
 218       audio: [
 219         // we favor VBR, if a good AAC encoder is available
 220         { name: 'libfdk_aac', priority: 200 },
 221         { name: 'aac', priority: 100 }
 222       ]
 223     }
 224   }
 225
 226   static get Instance () {
 227     return this.instance || (this.instance = new this())
 228   }
 229 }
 230
 231 // ---------------------------------------------------------------------------
 232
 233 export {
 234   VideoTranscodingProfilesManager
 235 }
 236
 237 // ---------------------------------------------------------------------------
 238 async function buildTargetBitrate (options: {
 239   input: string
 240   resolution: VideoResolution
 241   fps: number
 242 }) {
 243   const { input, resolution, fps } = options
 244   const probe = await ffprobePromise(input)
 245
 246   const videoStream = await getVideoStreamFromFile(input, probe)
 247   if (!videoStream) return undefined
 248
 249   const targetBitrate = getTargetBitrate(resolution, fps, VIDEO_TRANSCODING_FPS)
 250
 251   // Don't transcode to an higher bitrate than the original file
 252   const fileBitrate = await getVideoFileBitrate(input, probe)
 253   return Math.min(targetBitrate, fileBitrate)
 254 }