server/lib/transcoding/default-transcoding-profiles.ts

   1
   2 import { logger } from '@server/helpers/logger'
   3 import { getAverageBitrate, getMinLimitBitrate } from '@shared/core-utils'
   4 import { buildStreamSuffix, FFmpegCommandWrapper, ffprobePromise, getAudioStream, getMaxAudioBitrate } from '@shared/ffmpeg'
   5 import { AvailableEncoders, EncoderOptionsBuilder, EncoderOptionsBuilderParams, VideoResolution } from '@shared/models'
   6 import { canDoQuickAudioTranscode } from './transcoding-quick-transcode'
   7
   8 /**
   9  *
  10  * Available encoders and profiles for the transcoding jobs
  11  * These functions are used by ffmpeg-utils that will get the encoders and options depending on the chosen profile
  12  *
  13  * Resources:
  14  *  * https://slhck.info/video/2017/03/01/rate-control.html
  15  *  * https://trac.ffmpeg.org/wiki/Limiting%20the%20output%20bitrate
  16  */
  17
  18 // ---------------------------------------------------------------------------
  19 // Default builders
  20 // ---------------------------------------------------------------------------
  21
  22 const defaultX264VODOptionsBuilder: EncoderOptionsBuilder = (options: EncoderOptionsBuilderParams) => {
  23   const { fps, inputRatio, inputBitrate, resolution } = options
  24
  25   // TODO: remove in 4.2, fps is not optional anymore
  26   if (!fps) return { outputOptions: [ ] }
  27
  28   const targetBitrate = getTargetBitrate({ inputBitrate, ratio: inputRatio, fps, resolution })
  29
  30   return {
  31     outputOptions: [
  32       ...getCommonOutputOptions(targetBitrate),
  33
  34       `-r ${fps}`
  35     ]
  36   }
  37 }
  38
  39 const defaultX264LiveOptionsBuilder: EncoderOptionsBuilder = (options: EncoderOptionsBuilderParams) => {
  40   const { streamNum, fps, inputBitrate, inputRatio, resolution } = options
  41
  42   const targetBitrate = getTargetBitrate({ inputBitrate, ratio: inputRatio, fps, resolution })
  43
  44   return {
  45     outputOptions: [
  46       ...getCommonOutputOptions(targetBitrate, streamNum),
  47
  48       `${buildStreamSuffix('-r:v', streamNum)} ${fps}`,
  49       `${buildStreamSuffix('-b:v', streamNum)} ${targetBitrate}`
  50     ]
  51   }
  52 }
  53
  54 const defaultAACOptionsBuilder: EncoderOptionsBuilder = async ({ input, streamNum, canCopyAudio }) => {
  55   const probe = await ffprobePromise(input)
  56
  57   if (canCopyAudio && await canDoQuickAudioTranscode(input, probe)) {
  58     logger.debug('Copy audio stream %s by AAC encoder.', input)
  59     return { copy: true, outputOptions: [ ] }
  60   }
  61
  62   const parsedAudio = await getAudioStream(input, probe)
  63
  64   // We try to reduce the ceiling bitrate by making rough matches of bitrates
  65   // Of course this is far from perfect, but it might save some space in the end
  66
  67   const audioCodecName = parsedAudio.audioStream['codec_name']
  68
  69   const bitrate = getMaxAudioBitrate(audioCodecName, parsedAudio.bitrate)
  70
  71   logger.debug('Calculating audio bitrate of %s by AAC encoder.', input, { bitrate: parsedAudio.bitrate, audioCodecName })
  72
  73   // Force stereo as it causes some issues with HLS playback in Chrome
  74   const base = [ '-channel_layout', 'stereo' ]
  75
  76   if (bitrate !== -1) {
  77     return { outputOptions: base.concat([ buildStreamSuffix('-b:a', streamNum), bitrate + 'k' ]) }
  78   }
  79
  80   return { outputOptions: base }
  81 }
  82
  83 const defaultLibFDKAACVODOptionsBuilder: EncoderOptionsBuilder = ({ streamNum }) => {
  84   return { outputOptions: [ buildStreamSuffix('-q:a', streamNum), '5' ] }
  85 }
  86
  87 // ---------------------------------------------------------------------------
  88 // Profile manager to get and change default profiles
  89 // ---------------------------------------------------------------------------
  90
  91 class VideoTranscodingProfilesManager {
  92   private static instance: VideoTranscodingProfilesManager
  93
  94   // 1 === less priority
  95   private readonly encodersPriorities = {
  96     vod: this.buildDefaultEncodersPriorities(),
  97     live: this.buildDefaultEncodersPriorities()
  98   }
  99
 100   private readonly availableEncoders = {
 101     vod: {
 102       libx264: {
 103         default: defaultX264VODOptionsBuilder
 104       },
 105       aac: {
 106         default: defaultAACOptionsBuilder
 107       },
 108       libfdk_aac: {
 109         default: defaultLibFDKAACVODOptionsBuilder
 110       }
 111     },
 112     live: {
 113       libx264: {
 114         default: defaultX264LiveOptionsBuilder
 115       },
 116       aac: {
 117         default: defaultAACOptionsBuilder
 118       }
 119     }
 120   }
 121
 122   private availableProfiles = {
 123     vod: [] as string[],
 124     live: [] as string[]
 125   }
 126
 127   private constructor () {
 128     this.buildAvailableProfiles()
 129   }
 130
 131   getAvailableEncoders (): AvailableEncoders {
 132     return {
 133       available: this.availableEncoders,
 134       encodersToTry: {
 135         vod: {
 136           video: this.getEncodersByPriority('vod', 'video'),
 137           audio: this.getEncodersByPriority('vod', 'audio')
 138         },
 139         live: {
 140           video: this.getEncodersByPriority('live', 'video'),
 141           audio: this.getEncodersByPriority('live', 'audio')
 142         }
 143       }
 144     }
 145   }
 146
 147   getAvailableProfiles (type: 'vod' | 'live') {
 148     return this.availableProfiles[type]
 149   }
 150
 151   addProfile (options: {
 152     type: 'vod' | 'live'
 153     encoder: string
 154     profile: string
 155     builder: EncoderOptionsBuilder
 156   }) {
 157     const { type, encoder, profile, builder } = options
 158
 159     const encoders = this.availableEncoders[type]
 160
 161     if (!encoders[encoder]) encoders[encoder] = {}
 162     encoders[encoder][profile] = builder
 163
 164     this.buildAvailableProfiles()
 165   }
 166
 167   removeProfile (options: {
 168     type: 'vod' | 'live'
 169     encoder: string
 170     profile: string
 171   }) {
 172     const { type, encoder, profile } = options
 173
 174     delete this.availableEncoders[type][encoder][profile]
 175     this.buildAvailableProfiles()
 176   }
 177
 178   addEncoderPriority (type: 'vod' | 'live', streamType: 'audio' | 'video', encoder: string, priority: number) {
 179     this.encodersPriorities[type][streamType].push({ name: encoder, priority })
 180
 181     FFmpegCommandWrapper.resetSupportedEncoders()
 182   }
 183
 184   removeEncoderPriority (type: 'vod' | 'live', streamType: 'audio' | 'video', encoder: string, priority: number) {
 185     this.encodersPriorities[type][streamType] = this.encodersPriorities[type][streamType]
 186                                                     .filter(o => o.name !== encoder && o.priority !== priority)
 187
 188     FFmpegCommandWrapper.resetSupportedEncoders()
 189   }
 190
 191   private getEncodersByPriority (type: 'vod' | 'live', streamType: 'audio' | 'video') {
 192     return this.encodersPriorities[type][streamType]
 193       .sort((e1, e2) => {
 194         if (e1.priority > e2.priority) return -1
 195         else if (e1.priority === e2.priority) return 0
 196
 197         return 1
 198       })
 199       .map(e => e.name)
 200   }
 201
 202   private buildAvailableProfiles () {
 203     for (const type of [ 'vod', 'live' ]) {
 204       const result = new Set()
 205
 206       const encoders = this.availableEncoders[type]
 207
 208       for (const encoderName of Object.keys(encoders)) {
 209         for (const profile of Object.keys(encoders[encoderName])) {
 210           result.add(profile)
 211         }
 212       }
 213
 214       this.availableProfiles[type] = Array.from(result)
 215     }
 216
 217     logger.debug('Available transcoding profiles built.', { availableProfiles: this.availableProfiles })
 218   }
 219
 220   private buildDefaultEncodersPriorities () {
 221     return {
 222       video: [
 223         { name: 'libx264', priority: 100 }
 224       ],
 225
 226       // Try the first one, if not available try the second one etc
 227       audio: [
 228         // we favor VBR, if a good AAC encoder is available
 229         { name: 'libfdk_aac', priority: 200 },
 230         { name: 'aac', priority: 100 }
 231       ]
 232     }
 233   }
 234
 235   static get Instance () {
 236     return this.instance || (this.instance = new this())
 237   }
 238 }
 239
 240 // ---------------------------------------------------------------------------
 241
 242 export {
 243   VideoTranscodingProfilesManager
 244 }
 245
 246 // ---------------------------------------------------------------------------
 247
 248 function getTargetBitrate (options: {
 249   inputBitrate: number
 250   resolution: VideoResolution
 251   ratio: number
 252   fps: number
 253 }) {
 254   const { inputBitrate, resolution, ratio, fps } = options
 255
 256   const capped = capBitrate(inputBitrate, getAverageBitrate({ resolution, fps, ratio }))
 257   const limit = getMinLimitBitrate({ resolution, fps, ratio })
 258
 259   return Math.max(limit, capped)
 260 }
 261
 262 function capBitrate (inputBitrate: number, targetBitrate: number) {
 263   if (!inputBitrate) return targetBitrate
 264
 265   // Add 30% margin to input bitrate
 266   const inputBitrateWithMargin = inputBitrate + (inputBitrate * 0.3)
 267
 268   return Math.min(targetBitrate, inputBitrateWithMargin)
 269 }
 270
 271 function getCommonOutputOptions (targetBitrate: number, streamNum?: number) {
 272   return [
 273     `-preset veryfast`,
 274     `${buildStreamSuffix('-maxrate:v', streamNum)} ${targetBitrate}`,
 275     `${buildStreamSuffix('-bufsize:v', streamNum)} ${targetBitrate * 2}`,
 276
 277     // NOTE: b-strategy 1 - heuristic algorithm, 16 is optimal B-frames for it
 278     `-b_strategy 1`,
 279     // NOTE: Why 16: https://github.com/Chocobozzz/PeerTube/pull/774. b-strategy 2 -> B-frames<16
 280     `-bf 16`
 281   ]
 282 }