server/helpers/ffmpeg-utils.ts

   1 import * as ffmpeg from 'fluent-ffmpeg'
   2 import { join } from 'path'
   3 import { VideoResolution } from '../../shared/models/videos'
   4 import { CONFIG, VIDEO_TRANSCODING_FPS } from '../initializers'
   5 import { unlinkPromise } from './core-utils'
   6 import { processImage } from './image-utils'
   7 import { logger } from './logger'
   8 import { checkFFmpegEncoders } from '../initializers/checker'
   9
  10 async function getVideoFileResolution (path: string) {
  11   const videoStream = await getVideoFileStream(path)
  12
  13   return {
  14     videoFileResolution: Math.min(videoStream.height, videoStream.width),
  15     isPortraitMode: videoStream.height > videoStream.width
  16   }
  17 }
  18
  19 async function getVideoFileFPS (path: string) {
  20   const videoStream = await getVideoFileStream(path)
  21
  22   for (const key of [ 'r_frame_rate' , 'avg_frame_rate' ]) {
  23     const valuesText: string = videoStream[key]
  24     if (!valuesText) continue
  25
  26     const [ frames, seconds ] = valuesText.split('/')
  27     if (!frames || !seconds) continue
  28
  29     const result = parseInt(frames, 10) / parseInt(seconds, 10)
  30     if (result > 0) return Math.round(result)
  31   }
  32
  33   return 0
  34 }
  35
  36 function getDurationFromVideoFile (path: string) {
  37   return new Promise<number>((res, rej) => {
  38     ffmpeg.ffprobe(path, (err, metadata) => {
  39       if (err) return rej(err)
  40
  41       return res(Math.floor(metadata.format.duration))
  42     })
  43   })
  44 }
  45
  46 async function generateImageFromVideoFile (fromPath: string, folder: string, imageName: string, size: { width: number, height: number }) {
  47   const pendingImageName = 'pending-' + imageName
  48
  49   const options = {
  50     filename: pendingImageName,
  51     count: 1,
  52     folder
  53   }
  54
  55   const pendingImagePath = join(folder, pendingImageName)
  56
  57   try {
  58     await new Promise<string>((res, rej) => {
  59       ffmpeg(fromPath)
  60         .on('error', rej)
  61         .on('end', () => res(imageName))
  62         .thumbnail(options)
  63     })
  64
  65     const destination = join(folder, imageName)
  66     await processImage({ path: pendingImagePath }, destination, size)
  67   } catch (err) {
  68     logger.error('Cannot generate image from video %s.', fromPath, { err })
  69
  70     try {
  71       await unlinkPromise(pendingImagePath)
  72     } catch (err) {
  73       logger.debug('Cannot remove pending image path after generation error.', { err })
  74     }
  75   }
  76 }
  77
  78 type TranscodeOptions = {
  79   inputPath: string
  80   outputPath: string
  81   resolution?: VideoResolution
  82   isPortraitMode?: boolean
  83 }
  84
  85 function transcode (options: TranscodeOptions) {
  86   return new Promise<void>(async (res, rej) => {
  87     let command = ffmpeg(options.inputPath)
  88                     .output(options.outputPath)
  89                     .outputOption('-threads ' + CONFIG.TRANSCODING.THREADS)
  90                     .renice(5) // we don't want to make the system unrepsonsive
  91                      .preset(standard)
  92
  93     let fps = await getVideoFileFPS(options.inputPath)
  94     if (options.resolution !== undefined) {
  95       // '?x720' or '720x?' for example
  96       const size = options.isPortraitMode === true ? `${options.resolution}x?` : `?x${options.resolution}`
  97       command = command.size(size)
  98
  99       // On small/medium resolutions, limit FPS
 100       if (
 101         options.resolution < VIDEO_TRANSCODING_FPS.KEEP_ORIGIN_FPS_RESOLUTION_MIN &&
 102         fps > VIDEO_TRANSCODING_FPS.AVERAGE
 103       ) {
 104         fps = VIDEO_TRANSCODING_FPS.AVERAGE
 105       }
 106     }
 107
 108     if (fps) {
 109       // Hard FPS limits
 110       if (fps > VIDEO_TRANSCODING_FPS.MAX) fps = VIDEO_TRANSCODING_FPS.MAX
 111       else if (fps < VIDEO_TRANSCODING_FPS.MIN) fps = VIDEO_TRANSCODING_FPS.MIN
 112
 113       command = command.withFPS(fps)
 114     }
 115
 116     command
 117       .on('error', (err, stdout, stderr) => {
 118         logger.error('Error in transcoding job.', { stdout, stderr })
 119         return rej(err)
 120       })
 121       .on('end', res)
 122       .run()
 123   })
 124 }
 125
 126 // ---------------------------------------------------------------------------
 127
 128 export {
 129   getVideoFileResolution,
 130   getDurationFromVideoFile,
 131   generateImageFromVideoFile,
 132   transcode,
 133   getVideoFileFPS
 134 }
 135
 136 // ---------------------------------------------------------------------------
 137
 138 function getVideoFileStream (path: string) {
 139   return new Promise<any>((res, rej) => {
 140     ffmpeg.ffprobe(path, (err, metadata) => {
 141       if (err) return rej(err)
 142
 143       const videoStream = metadata.streams.find(s => s.codec_type === 'video')
 144       if (!videoStream) throw new Error('Cannot find video stream of ' + path)
 145
 146       return res(videoStream)
 147     })
 148   })
 149 }
 150
 151 /**
 152  * A slightly customised version of the 'veryfast' x264 preset
 153  *
 154  * The veryfast preset is right in the sweet spot of performance
 155  * and quality. Superfast and ultrafast will give you better
 156  * performance, but then quality is noticeably worse.
 157  */
 158 function veryfast (_ffmpeg) {
 159   _ffmpeg
 160     .preset(standard)
 161     .outputOption('-preset:v veryfast')
 162     .outputOption(['--aq-mode=2', '--aq-strength=1.3'])
 163   /*
 164   MAIN reference: https://slhck.info/video/2017/03/01/rate-control.html
 165   Our target situation is closer to a livestream than a stream,
 166   since we want to reduce as much a possible the encoding burden,
 167   altough not to the point of a livestream where there is a hard
 168   constraint on the frames per second to be encoded.
 169
 170   why '--aq-mode=2 --aq-strength=1.3' instead of '-profile:v main'?
 171     Make up for most of the loss of grain and macroblocking
 172     with less computing power.
 173   */
 174 }
 175
 176 /**
 177  * A preset optimised for a stillimage audio video
 178  */
 179 function audio (_ffmpeg) {
 180   _ffmpeg
 181     .preset(veryfast)
 182     .outputOption('-tune stillimage')
 183 }
 184
 185 /**
 186  * A toolbox to play with audio
 187  */
 188 namespace audio {
 189   export const get = (_ffmpeg, pos: number | string = 0) => {
 190     // without position, ffprobe considers the last input only
 191     // we make it consider the first input only
 192     // if you pass a file path to pos, then ffprobe acts on that file directly
 193     return new Promise<any>((res, rej) => {
 194       _ffmpeg
 195         .ffprobe(pos, (err,data) => {
 196           if (err) return rej(err)
 197
 198           if ('streams' in data) {
 199             return res(data['streams'].find(stream => stream['codec_type'] === 'audio'))
 200           } else {
 201             rej()
 202           }
 203         })
 204     })
 205   }
 206
 207   export namespace bitrate {
 208     export const baseKbitrate = 384
 209
 210     const toBits = (kbits: number): number => { return kbits * 8000 }
 211
 212     export const aac = (bitrate: number): number => {
 213       switch (true) {
 214       case bitrate > toBits(384):
 215         return baseKbitrate
 216       default:
 217         return -1 // we interpret it as a signal to copy the audio stream as is
 218       }
 219     }
 220
 221     export const mp3 = (bitrate: number): number => {
 222       switch (true) {
 223       case bitrate <= toBits(192):
 224         return 128
 225       case bitrate <= toBits(384):
 226         return 256
 227       default:
 228         return baseKbitrate
 229       }
 230     }
 231   }
 232 }
 233
 234 /**
 235  * Standard profile, with variable bitrate audio and faststart.
 236  *
 237  * As for the audio, quality '5' is the highest and ensures 96-112kbps/channel
 238  * See https://trac.ffmpeg.org/wiki/Encode/AAC#fdk_vbr
 239  */
 240 async function standard (_ffmpeg) {
 241   let _bitrate = audio.bitrate.baseKbitrate
 242   let localFfmpeg = _ffmpeg
 243     .format('mp4')
 244     .videoCodec('libx264')
 245     .outputOption('-level 3.1') // 3.1 is the minimal ressource allocation for our highest supported resolution
 246     .outputOption('-b_strategy 1') // NOTE: b-strategy 1 - heuristic algorythm, 16 is optimal B-frames for it
 247     .outputOption('-bf 16') // NOTE: Why 16: https://github.com/Chocobozzz/PeerTube/pull/774. b-strategy 2 -> B-frames<16
 248     .outputOption('-map_metadata -1') // strip all metadata
 249     .outputOption('-movflags faststart')
 250   let _audio = audio.get(localFfmpeg)
 251                     .then(res => res)
 252                     .catch(_ => undefined)
 253
 254   if (!_audio) return localFfmpeg.noAudio()
 255
 256   // we try to reduce the ceiling bitrate by making rough correspondances of bitrates
 257   // of course this is far from perfect, but it might save some space in the end
 258   if (audio.bitrate[_audio['codec_name']]) {
 259     _bitrate = audio.bitrate[_audio['codec_name']](_audio['bit_rate'])
 260     if (_bitrate === -1) {
 261       return localFfmpeg.audioCodec('copy')
 262     }
 263   }
 264
 265   // we favor VBR, if a good AAC encoder is available
 266   if ((await checkFFmpegEncoders()).get('libfdk_aac')) {
 267     return localFfmpeg
 268       .audioCodec('libfdk_aac')
 269       .audioQuality(5)
 270   }
 271
 272   return localFfmpeg.audioBitrate(_bitrate)
 273 }