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, FFMPEG_NICE } 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, { niceness: FFMPEG_NICE.THUMBNAIL })
  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, { niceness: FFMPEG_NICE.TRANSCODING })
  88                     .output(options.outputPath)
  89                     .preset(standard)
  90
  91     if (CONFIG.TRANSCODING.THREADS > 0) {
  92       // if we don't set any threads ffmpeg will chose automatically
  93       command = command.outputOption('-threads ' + CONFIG.TRANSCODING.THREADS)
  94     }
  95
  96     let fps = await getVideoFileFPS(options.inputPath)
  97     if (options.resolution !== undefined) {
  98       // '?x720' or '720x?' for example
  99       const size = options.isPortraitMode === true ? `${options.resolution}x?` : `?x${options.resolution}`
 100       command = command.size(size)
 101
 102       // On small/medium resolutions, limit FPS
 103       if (
 104         options.resolution < VIDEO_TRANSCODING_FPS.KEEP_ORIGIN_FPS_RESOLUTION_MIN &&
 105         fps > VIDEO_TRANSCODING_FPS.AVERAGE
 106       ) {
 107         fps = VIDEO_TRANSCODING_FPS.AVERAGE
 108       }
 109     }
 110
 111     if (fps) {
 112       // Hard FPS limits
 113       if (fps > VIDEO_TRANSCODING_FPS.MAX) fps = VIDEO_TRANSCODING_FPS.MAX
 114       else if (fps < VIDEO_TRANSCODING_FPS.MIN) fps = VIDEO_TRANSCODING_FPS.MIN
 115
 116       command = command.withFPS(fps)
 117     }
 118
 119     command
 120       .on('error', (err, stdout, stderr) => {
 121         logger.error('Error in transcoding job.', { stdout, stderr })
 122         return rej(err)
 123       })
 124       .on('end', res)
 125       .run()
 126   })
 127 }
 128
 129 // ---------------------------------------------------------------------------
 130
 131 export {
 132   getVideoFileResolution,
 133   getDurationFromVideoFile,
 134   generateImageFromVideoFile,
 135   transcode,
 136   getVideoFileFPS,
 137   audio
 138 }
 139
 140 // ---------------------------------------------------------------------------
 141
 142 function getVideoFileStream (path: string) {
 143   return new Promise<any>((res, rej) => {
 144     ffmpeg.ffprobe(path, (err, metadata) => {
 145       if (err) return rej(err)
 146
 147       const videoStream = metadata.streams.find(s => s.codec_type === 'video')
 148       if (!videoStream) throw new Error('Cannot find video stream of ' + path)
 149
 150       return res(videoStream)
 151     })
 152   })
 153 }
 154
 155 /**
 156  * A slightly customised version of the 'veryfast' x264 preset
 157  *
 158  * The veryfast preset is right in the sweet spot of performance
 159  * and quality. Superfast and ultrafast will give you better
 160  * performance, but then quality is noticeably worse.
 161  */
 162 function veryfast (_ffmpeg) {
 163   _ffmpeg
 164     .preset(standard)
 165     .outputOption('-preset:v veryfast')
 166     .outputOption(['--aq-mode=2', '--aq-strength=1.3'])
 167   /*
 168   MAIN reference: https://slhck.info/video/2017/03/01/rate-control.html
 169   Our target situation is closer to a livestream than a stream,
 170   since we want to reduce as much a possible the encoding burden,
 171   altough not to the point of a livestream where there is a hard
 172   constraint on the frames per second to be encoded.
 173
 174   why '--aq-mode=2 --aq-strength=1.3' instead of '-profile:v main'?
 175     Make up for most of the loss of grain and macroblocking
 176     with less computing power.
 177   */
 178 }
 179
 180 /**
 181  * A preset optimised for a stillimage audio video
 182  */
 183 function audio (_ffmpeg) {
 184   _ffmpeg
 185     .preset(veryfast)
 186     .outputOption('-tune stillimage')
 187 }
 188
 189 /**
 190  * A toolbox to play with audio
 191  */
 192 namespace audio {
 193   export const get = (_ffmpeg, pos: number | string = 0) => {
 194     // without position, ffprobe considers the last input only
 195     // we make it consider the first input only
 196     // if you pass a file path to pos, then ffprobe acts on that file directly
 197     return new Promise<{ absolutePath: string, audioStream?: any }>((res, rej) => {
 198       _ffmpeg.ffprobe(pos, (err,data) => {
 199         if (err) return rej(err)
 200
 201         if ('streams' in data) {
 202           const audioStream = data['streams'].find(stream => stream['codec_type'] === 'audio')
 203           if (audioStream) {
 204             return res({
 205               absolutePath: data.format.filename,
 206               audioStream
 207             })
 208           }
 209         }
 210         return res({ absolutePath: data.format.filename })
 211       })
 212     })
 213   }
 214
 215   export namespace bitrate {
 216     export const baseKbitrate = 384
 217
 218     const toBits = (kbits: number): number => { return kbits * 8000 }
 219
 220     export const aac = (bitrate: number): number => {
 221       switch (true) {
 222       case bitrate > toBits(baseKbitrate):
 223         return baseKbitrate
 224       default:
 225         return -1 // we interpret it as a signal to copy the audio stream as is
 226       }
 227     }
 228
 229     export const mp3 = (bitrate: number): number => {
 230       /*
 231       a 192kbit/sec mp3 doesn't hold as much information as a 192kbit/sec aac.
 232       That's why, when using aac, we can go to lower kbit/sec. The equivalences
 233       made here are not made to be accurate, especially with good mp3 encoders.
 234       */
 235       switch (true) {
 236       case bitrate <= toBits(192):
 237         return 128
 238       case bitrate <= toBits(384):
 239         return 256
 240       default:
 241         return baseKbitrate
 242       }
 243     }
 244   }
 245 }
 246
 247 /**
 248  * Standard profile, with variable bitrate audio and faststart.
 249  *
 250  * As for the audio, quality '5' is the highest and ensures 96-112kbps/channel
 251  * See https://trac.ffmpeg.org/wiki/Encode/AAC#fdk_vbr
 252  */
 253 async function standard (_ffmpeg) {
 254   let _bitrate = audio.bitrate.baseKbitrate
 255   let localFfmpeg = _ffmpeg
 256     .format('mp4')
 257     .videoCodec('libx264')
 258     .outputOption('-level 3.1') // 3.1 is the minimal ressource allocation for our highest supported resolution
 259     .outputOption('-b_strategy 1') // NOTE: b-strategy 1 - heuristic algorythm, 16 is optimal B-frames for it
 260     .outputOption('-bf 16') // NOTE: Why 16: https://github.com/Chocobozzz/PeerTube/pull/774. b-strategy 2 -> B-frames<16
 261     .outputOption('-map_metadata -1') // strip all metadata
 262     .outputOption('-movflags faststart')
 263   const _audio = await audio.get(localFfmpeg)
 264
 265   if (!_audio.audioStream) {
 266     return localFfmpeg.noAudio()
 267   }
 268
 269   // we try to reduce the ceiling bitrate by making rough correspondances of bitrates
 270   // of course this is far from perfect, but it might save some space in the end
 271   if (audio.bitrate[_audio.audioStream['codec_name']]) {
 272     _bitrate = audio.bitrate[_audio.audioStream['codec_name']](_audio.audioStream['bit_rate'])
 273     if (_bitrate === -1) {
 274       return localFfmpeg.audioCodec('copy')
 275     }
 276   }
 277
 278   // we favor VBR, if a good AAC encoder is available
 279   if ((await checkFFmpegEncoders()).get('libfdk_aac')) {
 280     return localFfmpeg
 281       .audioCodec('libfdk_aac')
 282       .audioQuality(5)
 283   }
 284
 285   return localFfmpeg.audioBitrate(_bitrate)
 286 }