server/helpers/ffmpeg-utils.ts

   1 import * as ffmpeg from 'fluent-ffmpeg'
   2 import { dirname, join } from 'path'
   3 import { getTargetBitrate, getMaxBitrate, VideoResolution } from '../../shared/models/videos'
   4 import { FFMPEG_NICE, VIDEO_TRANSCODING_FPS } from '../initializers/constants'
   5 import { processImage } from './image-utils'
   6 import { logger } from './logger'
   7 import { checkFFmpegEncoders } from '../initializers/checker-before-init'
   8 import { readFile, remove, writeFile } from 'fs-extra'
   9 import { CONFIG } from '../initializers/config'
  10
  11 function computeResolutionsToTranscode (videoFileHeight: number) {
  12   const resolutionsEnabled: number[] = []
  13   const configResolutions = CONFIG.TRANSCODING.RESOLUTIONS
  14
  15   // Put in the order we want to proceed jobs
  16   const resolutions = [
  17     VideoResolution.H_480P,
  18     VideoResolution.H_360P,
  19     VideoResolution.H_720P,
  20     VideoResolution.H_240P,
  21     VideoResolution.H_1080P
  22   ]
  23
  24   for (const resolution of resolutions) {
  25     if (configResolutions[ resolution + 'p' ] === true && videoFileHeight > resolution) {
  26       resolutionsEnabled.push(resolution)
  27     }
  28   }
  29
  30   return resolutionsEnabled
  31 }
  32
  33 async function getVideoFileSize (path: string) {
  34   const videoStream = await getVideoStreamFromFile(path)
  35
  36   return {
  37     width: videoStream.width,
  38     height: videoStream.height
  39   }
  40 }
  41
  42 async function getVideoFileResolution (path: string) {
  43   const size = await getVideoFileSize(path)
  44
  45   return {
  46     videoFileResolution: Math.min(size.height, size.width),
  47     isPortraitMode: size.height > size.width
  48   }
  49 }
  50
  51 async function getVideoFileFPS (path: string) {
  52   const videoStream = await getVideoStreamFromFile(path)
  53
  54   for (const key of [ 'avg_frame_rate', 'r_frame_rate' ]) {
  55     const valuesText: string = videoStream[key]
  56     if (!valuesText) continue
  57
  58     const [ frames, seconds ] = valuesText.split('/')
  59     if (!frames || !seconds) continue
  60
  61     const result = parseInt(frames, 10) / parseInt(seconds, 10)
  62     if (result > 0) return Math.round(result)
  63   }
  64
  65   return 0
  66 }
  67
  68 async function getVideoFileBitrate (path: string) {
  69   return new Promise<number>((res, rej) => {
  70     ffmpeg.ffprobe(path, (err, metadata) => {
  71       if (err) return rej(err)
  72
  73       return res(metadata.format.bit_rate)
  74     })
  75   })
  76 }
  77
  78 function getDurationFromVideoFile (path: string) {
  79   return new Promise<number>((res, rej) => {
  80     ffmpeg.ffprobe(path, (err, metadata) => {
  81       if (err) return rej(err)
  82
  83       return res(Math.floor(metadata.format.duration))
  84     })
  85   })
  86 }
  87
  88 async function generateImageFromVideoFile (fromPath: string, folder: string, imageName: string, size: { width: number, height: number }) {
  89   const pendingImageName = 'pending-' + imageName
  90
  91   const options = {
  92     filename: pendingImageName,
  93     count: 1,
  94     folder
  95   }
  96
  97   const pendingImagePath = join(folder, pendingImageName)
  98
  99   try {
 100     await new Promise<string>((res, rej) => {
 101       ffmpeg(fromPath, { niceness: FFMPEG_NICE.THUMBNAIL })
 102         .on('error', rej)
 103         .on('end', () => res(imageName))
 104         .thumbnail(options)
 105     })
 106
 107     const destination = join(folder, imageName)
 108     await processImage(pendingImagePath, destination, size)
 109   } catch (err) {
 110     logger.error('Cannot generate image from video %s.', fromPath, { err })
 111
 112     try {
 113       await remove(pendingImagePath)
 114     } catch (err) {
 115       logger.debug('Cannot remove pending image path after generation error.', { err })
 116     }
 117   }
 118 }
 119
 120 type TranscodeOptions = {
 121   inputPath: string
 122   outputPath: string
 123   resolution: VideoResolution
 124   isPortraitMode?: boolean
 125   doQuickTranscode?: Boolean
 126
 127   hlsPlaylist?: {
 128     videoFilename: string
 129   }
 130 }
 131
 132 function transcode (options: TranscodeOptions) {
 133   return new Promise<void>(async (res, rej) => {
 134     try {
 135       let command = ffmpeg(options.inputPath, { niceness: FFMPEG_NICE.TRANSCODING })
 136         .output(options.outputPath)
 137
 138       if (options.doQuickTranscode) {
 139         if (options.hlsPlaylist) {
 140           throw(Error("Quick transcode and HLS can't be used at the same time"))
 141         }
 142         command
 143           .format('mp4')
 144           .addOption('-c:v copy')
 145           .addOption('-c:a copy')
 146           .outputOption('-map_metadata -1') // strip all metadata
 147           .outputOption('-movflags faststart')
 148       } else if (options.hlsPlaylist) {
 149         command = await buildHLSCommand(command, options)
 150       } else {
 151         command = await buildx264Command(command, options)
 152       }
 153
 154       if (CONFIG.TRANSCODING.THREADS > 0) {
 155         // if we don't set any threads ffmpeg will chose automatically
 156         command = command.outputOption('-threads ' + CONFIG.TRANSCODING.THREADS)
 157       }
 158
 159       command
 160         .on('error', (err, stdout, stderr) => {
 161           logger.error('Error in transcoding job.', { stdout, stderr })
 162           return rej(err)
 163         })
 164         .on('end', () => {
 165           return onTranscodingSuccess(options)
 166             .then(() => res())
 167             .catch(err => rej(err))
 168         })
 169         .run()
 170     } catch (err) {
 171       return rej(err)
 172     }
 173   })
 174 }
 175
 176 async function canDoQuickTranscode (path: string) {
 177   // NOTE: This could be optimized by running ffprobe only once (but it runs fast anyway)
 178   const videoStream = await getVideoStreamFromFile(path)
 179   const parsedAudio = await audio.get(path)
 180   const fps = await getVideoFileFPS(path)
 181   const bitRate = await getVideoFileBitrate(path)
 182   const resolution = await getVideoFileResolution(path)
 183
 184   // check video params
 185   if (videoStream[ 'codec_name' ] !== 'h264')
 186     return false
 187   if (fps < VIDEO_TRANSCODING_FPS.MIN || fps > VIDEO_TRANSCODING_FPS.MAX)
 188     return false
 189   if (bitRate > getMaxBitrate(resolution.videoFileResolution, fps, VIDEO_TRANSCODING_FPS))
 190     return false
 191
 192     // check audio params (if audio stream exists)
 193   if (parsedAudio.audioStream) {
 194     if (parsedAudio.audioStream[ 'codec_name' ] !== 'aac')
 195       return false
 196     const maxAudioBitrate = audio.bitrate[ 'aac' ](parsedAudio.audioStream[ 'bit_rate' ])
 197     if (maxAudioBitrate != -1 && parsedAudio.audioStream[ 'bit_rate' ] > maxAudioBitrate)
 198       return false
 199   }
 200
 201   return true
 202 }
 203
 204 // ---------------------------------------------------------------------------
 205
 206 export {
 207   getVideoFileSize,
 208   getVideoFileResolution,
 209   getDurationFromVideoFile,
 210   generateImageFromVideoFile,
 211   transcode,
 212   getVideoFileFPS,
 213   computeResolutionsToTranscode,
 214   audio,
 215   getVideoFileBitrate,
 216   canDoQuickTranscode
 217 }
 218
 219 // ---------------------------------------------------------------------------
 220
 221 async function buildx264Command (command: ffmpeg.FfmpegCommand, options: TranscodeOptions) {
 222   let fps = await getVideoFileFPS(options.inputPath)
 223   // On small/medium resolutions, limit FPS
 224   if (
 225     options.resolution !== undefined &&
 226     options.resolution < VIDEO_TRANSCODING_FPS.KEEP_ORIGIN_FPS_RESOLUTION_MIN &&
 227     fps > VIDEO_TRANSCODING_FPS.AVERAGE
 228   ) {
 229     fps = VIDEO_TRANSCODING_FPS.AVERAGE
 230   }
 231
 232   command = await presetH264(command, options.resolution, fps)
 233
 234   if (options.resolution !== undefined) {
 235     // '?x720' or '720x?' for example
 236     const size = options.isPortraitMode === true ? `${options.resolution}x?` : `?x${options.resolution}`
 237     command = command.size(size)
 238   }
 239
 240   if (fps) {
 241     // Hard FPS limits
 242     if (fps > VIDEO_TRANSCODING_FPS.MAX) fps = VIDEO_TRANSCODING_FPS.MAX
 243     else if (fps < VIDEO_TRANSCODING_FPS.MIN) fps = VIDEO_TRANSCODING_FPS.MIN
 244
 245     command = command.withFPS(fps)
 246   }
 247
 248   return command
 249 }
 250
 251 async function buildHLSCommand (command: ffmpeg.FfmpegCommand, options: TranscodeOptions) {
 252   const videoPath = getHLSVideoPath(options)
 253
 254   command = await presetCopy(command)
 255
 256   command = command.outputOption('-hls_time 4')
 257                    .outputOption('-hls_list_size 0')
 258                    .outputOption('-hls_playlist_type vod')
 259                    .outputOption('-hls_segment_filename ' + videoPath)
 260                    .outputOption('-hls_segment_type fmp4')
 261                    .outputOption('-f hls')
 262                    .outputOption('-hls_flags single_file')
 263
 264   return command
 265 }
 266
 267 function getHLSVideoPath (options: TranscodeOptions) {
 268   return `${dirname(options.outputPath)}/${options.hlsPlaylist.videoFilename}`
 269 }
 270
 271 async function onTranscodingSuccess (options: TranscodeOptions) {
 272   if (!options.hlsPlaylist) return
 273
 274   // Fix wrong mapping with some ffmpeg versions
 275   const fileContent = await readFile(options.outputPath)
 276
 277   const videoFileName = options.hlsPlaylist.videoFilename
 278   const videoFilePath = getHLSVideoPath(options)
 279
 280   const newContent = fileContent.toString()
 281                                 .replace(`#EXT-X-MAP:URI="${videoFilePath}",`, `#EXT-X-MAP:URI="${videoFileName}",`)
 282
 283   await writeFile(options.outputPath, newContent)
 284 }
 285
 286 function getVideoStreamFromFile (path: string) {
 287   return new Promise<any>((res, rej) => {
 288     ffmpeg.ffprobe(path, (err, metadata) => {
 289       if (err) return rej(err)
 290
 291       const videoStream = metadata.streams.find(s => s.codec_type === 'video')
 292       if (!videoStream) return rej(new Error('Cannot find video stream of ' + path))
 293
 294       return res(videoStream)
 295     })
 296   })
 297 }
 298
 299 /**
 300  * A slightly customised version of the 'veryfast' x264 preset
 301  *
 302  * The veryfast preset is right in the sweet spot of performance
 303  * and quality. Superfast and ultrafast will give you better
 304  * performance, but then quality is noticeably worse.
 305  */
 306 async function presetH264VeryFast (command: ffmpeg.FfmpegCommand, resolution: VideoResolution, fps: number): Promise<ffmpeg.FfmpegCommand> {
 307   let localCommand = await presetH264(command, resolution, fps)
 308   localCommand = localCommand.outputOption('-preset:v veryfast')
 309              .outputOption([ '--aq-mode=2', '--aq-strength=1.3' ])
 310   /*
 311   MAIN reference: https://slhck.info/video/2017/03/01/rate-control.html
 312   Our target situation is closer to a livestream than a stream,
 313   since we want to reduce as much a possible the encoding burden,
 314   altough not to the point of a livestream where there is a hard
 315   constraint on the frames per second to be encoded.
 316
 317   why '--aq-mode=2 --aq-strength=1.3' instead of '-profile:v main'?
 318     Make up for most of the loss of grain and macroblocking
 319     with less computing power.
 320   */
 321
 322   return localCommand
 323 }
 324
 325 /**
 326  * A preset optimised for a stillimage audio video
 327  */
 328 async function presetStillImageWithAudio (
 329   command: ffmpeg.FfmpegCommand,
 330   resolution: VideoResolution,
 331   fps: number
 332 ): Promise<ffmpeg.FfmpegCommand> {
 333   let localCommand = await presetH264VeryFast(command, resolution, fps)
 334   localCommand = localCommand.outputOption('-tune stillimage')
 335
 336   return localCommand
 337 }
 338
 339 /**
 340  * A toolbox to play with audio
 341  */
 342 namespace audio {
 343   export const get = (option: ffmpeg.FfmpegCommand | string) => {
 344     // without position, ffprobe considers the last input only
 345     // we make it consider the first input only
 346     // if you pass a file path to pos, then ffprobe acts on that file directly
 347     return new Promise<{ absolutePath: string, audioStream?: any }>((res, rej) => {
 348
 349       function parseFfprobe (err: any, data: ffmpeg.FfprobeData) {
 350         if (err) return rej(err)
 351
 352         if ('streams' in data) {
 353           const audioStream = data.streams.find(stream => stream['codec_type'] === 'audio')
 354           if (audioStream) {
 355             return res({
 356               absolutePath: data.format.filename,
 357               audioStream
 358             })
 359           }
 360         }
 361
 362         return res({ absolutePath: data.format.filename })
 363       }
 364
 365       if (typeof option === 'string') {
 366         return ffmpeg.ffprobe(option, parseFfprobe)
 367       }
 368
 369       return option.ffprobe(parseFfprobe)
 370     })
 371   }
 372
 373   export namespace bitrate {
 374     const baseKbitrate = 384
 375
 376     const toBits = (kbits: number): number => { return kbits * 8000 }
 377
 378     export const aac = (bitrate: number): number => {
 379       switch (true) {
 380       case bitrate > toBits(baseKbitrate):
 381         return baseKbitrate
 382       default:
 383         return -1 // we interpret it as a signal to copy the audio stream as is
 384       }
 385     }
 386
 387     export const mp3 = (bitrate: number): number => {
 388       /*
 389       a 192kbit/sec mp3 doesn't hold as much information as a 192kbit/sec aac.
 390       That's why, when using aac, we can go to lower kbit/sec. The equivalences
 391       made here are not made to be accurate, especially with good mp3 encoders.
 392       */
 393       switch (true) {
 394       case bitrate <= toBits(192):
 395         return 128
 396       case bitrate <= toBits(384):
 397         return 256
 398       default:
 399         return baseKbitrate
 400       }
 401     }
 402   }
 403 }
 404
 405 /**
 406  * Standard profile, with variable bitrate audio and faststart.
 407  *
 408  * As for the audio, quality '5' is the highest and ensures 96-112kbps/channel
 409  * See https://trac.ffmpeg.org/wiki/Encode/AAC#fdk_vbr
 410  */
 411 async function presetH264 (command: ffmpeg.FfmpegCommand, resolution: VideoResolution, fps: number): Promise<ffmpeg.FfmpegCommand> {
 412   let localCommand = command
 413     .format('mp4')
 414     .videoCodec('libx264')
 415     .outputOption('-level 3.1') // 3.1 is the minimal ressource allocation for our highest supported resolution
 416     .outputOption('-b_strategy 1') // NOTE: b-strategy 1 - heuristic algorythm, 16 is optimal B-frames for it
 417     .outputOption('-bf 16') // NOTE: Why 16: https://github.com/Chocobozzz/PeerTube/pull/774. b-strategy 2 -> B-frames<16
 418     .outputOption('-pix_fmt yuv420p') // allows import of source material with incompatible pixel formats (e.g. MJPEG video)
 419     .outputOption('-map_metadata -1') // strip all metadata
 420     .outputOption('-movflags faststart')
 421
 422   const parsedAudio = await audio.get(localCommand)
 423
 424   if (!parsedAudio.audioStream) {
 425     localCommand = localCommand.noAudio()
 426   } else if ((await checkFFmpegEncoders()).get('libfdk_aac')) { // we favor VBR, if a good AAC encoder is available
 427     localCommand = localCommand
 428       .audioCodec('libfdk_aac')
 429       .audioQuality(5)
 430   } else {
 431     // we try to reduce the ceiling bitrate by making rough correspondances of bitrates
 432     // of course this is far from perfect, but it might save some space in the end
 433     const audioCodecName = parsedAudio.audioStream[ 'codec_name' ]
 434     let bitrate: number
 435     if (audio.bitrate[ audioCodecName ]) {
 436       localCommand = localCommand.audioCodec('aac')
 437
 438       bitrate = audio.bitrate[ audioCodecName ](parsedAudio.audioStream[ 'bit_rate' ])
 439       if (bitrate !== undefined && bitrate !== -1) localCommand = localCommand.audioBitrate(bitrate)
 440     }
 441   }
 442
 443   // Constrained Encoding (VBV)
 444   // https://slhck.info/video/2017/03/01/rate-control.html
 445   // https://trac.ffmpeg.org/wiki/Limiting%20the%20output%20bitrate
 446   const targetBitrate = getTargetBitrate(resolution, fps, VIDEO_TRANSCODING_FPS)
 447   localCommand = localCommand.outputOptions([`-maxrate ${ targetBitrate }`, `-bufsize ${ targetBitrate * 2 }`])
 448
 449   // Keyframe interval of 2 seconds for faster seeking and resolution switching.
 450   // https://streaminglearningcenter.com/blogs/whats-the-right-keyframe-interval.html
 451   // https://superuser.com/a/908325
 452   localCommand = localCommand.outputOption(`-g ${ fps * 2 }`)
 453
 454   return localCommand
 455 }
 456
 457 async function presetCopy (command: ffmpeg.FfmpegCommand): Promise<ffmpeg.FfmpegCommand> {
 458   return command
 459     .format('mp4')
 460     .videoCodec('copy')
 461     .audioCodec('copy')
 462 }