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, FFMPEG_NICE, VIDEO_TRANSCODING_FPS } from '../initializers'
   5 import { processImage } from './image-utils'
   6 import { logger } from './logger'
   7 import { checkFFmpegEncoders } from '../initializers/checker-before-init'
   8 import { remove } from 'fs-extra'
   9
  10 function computeResolutionsToTranscode (videoFileHeight: number) {
  11   const resolutionsEnabled: number[] = []
  12   const configResolutions = CONFIG.TRANSCODING.RESOLUTIONS
  13
  14   // Put in the order we want to proceed jobs
  15   const resolutions = [
  16     VideoResolution.H_480P,
  17     VideoResolution.H_360P,
  18     VideoResolution.H_720P,
  19     VideoResolution.H_240P,
  20     VideoResolution.H_1080P
  21   ]
  22
  23   for (const resolution of resolutions) {
  24     if (configResolutions[ resolution + 'p' ] === true && videoFileHeight > resolution) {
  25       resolutionsEnabled.push(resolution)
  26     }
  27   }
  28
  29   return resolutionsEnabled
  30 }
  31
  32 async function getVideoFileResolution (path: string) {
  33   const videoStream = await getVideoFileStream(path)
  34
  35   return {
  36     videoFileResolution: Math.min(videoStream.height, videoStream.width),
  37     isPortraitMode: videoStream.height > videoStream.width
  38   }
  39 }
  40
  41 async function getVideoFileFPS (path: string) {
  42   const videoStream = await getVideoFileStream(path)
  43
  44   for (const key of [ 'r_frame_rate' , 'avg_frame_rate' ]) {
  45     const valuesText: string = videoStream[key]
  46     if (!valuesText) continue
  47
  48     const [ frames, seconds ] = valuesText.split('/')
  49     if (!frames || !seconds) continue
  50
  51     const result = parseInt(frames, 10) / parseInt(seconds, 10)
  52     if (result > 0) return Math.round(result)
  53   }
  54
  55   return 0
  56 }
  57
  58 function getDurationFromVideoFile (path: string) {
  59   return new Promise<number>((res, rej) => {
  60     ffmpeg.ffprobe(path, (err, metadata) => {
  61       if (err) return rej(err)
  62
  63       return res(Math.floor(metadata.format.duration))
  64     })
  65   })
  66 }
  67
  68 async function generateImageFromVideoFile (fromPath: string, folder: string, imageName: string, size: { width: number, height: number }) {
  69   const pendingImageName = 'pending-' + imageName
  70
  71   const options = {
  72     filename: pendingImageName,
  73     count: 1,
  74     folder
  75   }
  76
  77   const pendingImagePath = join(folder, pendingImageName)
  78
  79   try {
  80     await new Promise<string>((res, rej) => {
  81       ffmpeg(fromPath, { niceness: FFMPEG_NICE.THUMBNAIL })
  82         .on('error', rej)
  83         .on('end', () => res(imageName))
  84         .thumbnail(options)
  85     })
  86
  87     const destination = join(folder, imageName)
  88     await processImage({ path: pendingImagePath }, destination, size)
  89   } catch (err) {
  90     logger.error('Cannot generate image from video %s.', fromPath, { err })
  91
  92     try {
  93       await remove(pendingImagePath)
  94     } catch (err) {
  95       logger.debug('Cannot remove pending image path after generation error.', { err })
  96     }
  97   }
  98 }
  99
 100 type TranscodeOptions = {
 101   inputPath: string
 102   outputPath: string
 103   resolution?: VideoResolution
 104   isPortraitMode?: boolean
 105 }
 106
 107 function transcode (options: TranscodeOptions) {
 108   return new Promise<void>(async (res, rej) => {
 109     let command = ffmpeg(options.inputPath, { niceness: FFMPEG_NICE.TRANSCODING })
 110                     .output(options.outputPath)
 111                     .preset(standard)
 112
 113     if (CONFIG.TRANSCODING.THREADS > 0) {
 114       // if we don't set any threads ffmpeg will chose automatically
 115       command = command.outputOption('-threads ' + CONFIG.TRANSCODING.THREADS)
 116     }
 117
 118     let fps = await getVideoFileFPS(options.inputPath)
 119     if (options.resolution !== undefined) {
 120       // '?x720' or '720x?' for example
 121       const size = options.isPortraitMode === true ? `${options.resolution}x?` : `?x${options.resolution}`
 122       command = command.size(size)
 123
 124       // On small/medium resolutions, limit FPS
 125       if (
 126         options.resolution < VIDEO_TRANSCODING_FPS.KEEP_ORIGIN_FPS_RESOLUTION_MIN &&
 127         fps > VIDEO_TRANSCODING_FPS.AVERAGE
 128       ) {
 129         fps = VIDEO_TRANSCODING_FPS.AVERAGE
 130       }
 131     }
 132
 133     if (fps) {
 134       // Hard FPS limits
 135       if (fps > VIDEO_TRANSCODING_FPS.MAX) fps = VIDEO_TRANSCODING_FPS.MAX
 136       else if (fps < VIDEO_TRANSCODING_FPS.MIN) fps = VIDEO_TRANSCODING_FPS.MIN
 137
 138       command = command.withFPS(fps)
 139     }
 140
 141     command
 142       .on('error', (err, stdout, stderr) => {
 143         logger.error('Error in transcoding job.', { stdout, stderr })
 144         return rej(err)
 145       })
 146       .on('end', res)
 147       .run()
 148   })
 149 }
 150
 151 // ---------------------------------------------------------------------------
 152
 153 export {
 154   getVideoFileResolution,
 155   getDurationFromVideoFile,
 156   generateImageFromVideoFile,
 157   transcode,
 158   getVideoFileFPS,
 159   computeResolutionsToTranscode,
 160   audio
 161 }
 162
 163 // ---------------------------------------------------------------------------
 164
 165 function getVideoFileStream (path: string) {
 166   return new Promise<any>((res, rej) => {
 167     ffmpeg.ffprobe(path, (err, metadata) => {
 168       if (err) return rej(err)
 169
 170       const videoStream = metadata.streams.find(s => s.codec_type === 'video')
 171       if (!videoStream) throw new Error('Cannot find video stream of ' + path)
 172
 173       return res(videoStream)
 174     })
 175   })
 176 }
 177
 178 /**
 179  * A slightly customised version of the 'veryfast' x264 preset
 180  *
 181  * The veryfast preset is right in the sweet spot of performance
 182  * and quality. Superfast and ultrafast will give you better
 183  * performance, but then quality is noticeably worse.
 184  */
 185 function veryfast (_ffmpeg) {
 186   _ffmpeg
 187     .preset(standard)
 188     .outputOption('-preset:v veryfast')
 189     .outputOption(['--aq-mode=2', '--aq-strength=1.3'])
 190   /*
 191   MAIN reference: https://slhck.info/video/2017/03/01/rate-control.html
 192   Our target situation is closer to a livestream than a stream,
 193   since we want to reduce as much a possible the encoding burden,
 194   altough not to the point of a livestream where there is a hard
 195   constraint on the frames per second to be encoded.
 196
 197   why '--aq-mode=2 --aq-strength=1.3' instead of '-profile:v main'?
 198     Make up for most of the loss of grain and macroblocking
 199     with less computing power.
 200   */
 201 }
 202
 203 /**
 204  * A preset optimised for a stillimage audio video
 205  */
 206 function audio (_ffmpeg) {
 207   _ffmpeg
 208     .preset(veryfast)
 209     .outputOption('-tune stillimage')
 210 }
 211
 212 /**
 213  * A toolbox to play with audio
 214  */
 215 namespace audio {
 216   export const get = (_ffmpeg, pos: number | string = 0) => {
 217     // without position, ffprobe considers the last input only
 218     // we make it consider the first input only
 219     // if you pass a file path to pos, then ffprobe acts on that file directly
 220     return new Promise<{ absolutePath: string, audioStream?: any }>((res, rej) => {
 221       _ffmpeg.ffprobe(pos, (err,data) => {
 222         if (err) return rej(err)
 223
 224         if ('streams' in data) {
 225           const audioStream = data['streams'].find(stream => stream['codec_type'] === 'audio')
 226           if (audioStream) {
 227             return res({
 228               absolutePath: data.format.filename,
 229               audioStream
 230             })
 231           }
 232         }
 233         return res({ absolutePath: data.format.filename })
 234       })
 235     })
 236   }
 237
 238   export namespace bitrate {
 239     const baseKbitrate = 384
 240
 241     const toBits = (kbits: number): number => { return kbits * 8000 }
 242
 243     export const aac = (bitrate: number): number => {
 244       switch (true) {
 245       case bitrate > toBits(baseKbitrate):
 246         return baseKbitrate
 247       default:
 248         return -1 // we interpret it as a signal to copy the audio stream as is
 249       }
 250     }
 251
 252     export const mp3 = (bitrate: number): number => {
 253       /*
 254       a 192kbit/sec mp3 doesn't hold as much information as a 192kbit/sec aac.
 255       That's why, when using aac, we can go to lower kbit/sec. The equivalences
 256       made here are not made to be accurate, especially with good mp3 encoders.
 257       */
 258       switch (true) {
 259       case bitrate <= toBits(192):
 260         return 128
 261       case bitrate <= toBits(384):
 262         return 256
 263       default:
 264         return baseKbitrate
 265       }
 266     }
 267   }
 268 }
 269
 270 /**
 271  * Standard profile, with variable bitrate audio and faststart.
 272  *
 273  * As for the audio, quality '5' is the highest and ensures 96-112kbps/channel
 274  * See https://trac.ffmpeg.org/wiki/Encode/AAC#fdk_vbr
 275  */
 276 async function standard (_ffmpeg) {
 277   let localFfmpeg = _ffmpeg
 278     .format('mp4')
 279     .videoCodec('libx264')
 280     .outputOption('-level 3.1') // 3.1 is the minimal ressource allocation for our highest supported resolution
 281     .outputOption('-b_strategy 1') // NOTE: b-strategy 1 - heuristic algorythm, 16 is optimal B-frames for it
 282     .outputOption('-bf 16') // NOTE: Why 16: https://github.com/Chocobozzz/PeerTube/pull/774. b-strategy 2 -> B-frames<16
 283     .outputOption('-map_metadata -1') // strip all metadata
 284     .outputOption('-movflags faststart')
 285   const _audio = await audio.get(localFfmpeg)
 286
 287   if (!_audio.audioStream) {
 288     return localFfmpeg.noAudio()
 289   }
 290
 291   // we favor VBR, if a good AAC encoder is available
 292   if ((await checkFFmpegEncoders()).get('libfdk_aac')) {
 293     return localFfmpeg
 294       .audioCodec('libfdk_aac')
 295       .audioQuality(5)
 296   }
 297
 298   // we try to reduce the ceiling bitrate by making rough correspondances of bitrates
 299   // of course this is far from perfect, but it might save some space in the end
 300   const audioCodecName = _audio.audioStream['codec_name']
 301   let bitrate: number
 302   if (audio.bitrate[audioCodecName]) {
 303     bitrate = audio.bitrate[audioCodecName](_audio.audioStream['bit_rate'])
 304
 305     if (bitrate === -1) return localFfmpeg.audioCodec('copy')
 306   }
 307
 308   if (bitrate !== undefined) return localFfmpeg.audioBitrate(bitrate)
 309
 310   return localFfmpeg
 311 }