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_NOVIDEO,
  18     VideoResolution.H_480P,
  19     VideoResolution.H_360P,
  20     VideoResolution.H_720P,
  21     VideoResolution.H_240P,
  22     VideoResolution.H_1080P,
  23     VideoResolution.H_4K
  24   ]
  25
  26   for (const resolution of resolutions) {
  27     if (configResolutions[ resolution + 'p' ] === true && videoFileHeight > resolution) {
  28       resolutionsEnabled.push(resolution)
  29     }
  30   }
  31
  32   return resolutionsEnabled
  33 }
  34
  35 async function getVideoFileSize (path: string) {
  36   const videoStream = await getVideoStreamFromFile(path)
  37
  38   return videoStream == null
  39     ? {
  40         width: 0,
  41         height: 0
  42       }
  43     : {
  44         width: videoStream.width,
  45         height: videoStream.height
  46       }
  47 }
  48
  49 async function getVideoFileResolution (path: string) {
  50   const size = await getVideoFileSize(path)
  51
  52   return {
  53     videoFileResolution: Math.min(size.height, size.width),
  54     isPortraitMode: size.height > size.width
  55   }
  56 }
  57
  58 async function getVideoFileFPS (path: string) {
  59   const videoStream = await getVideoStreamFromFile(path)
  60
  61   if (videoStream == null) {
  62       return 0
  63   }
  64
  65   for (const key of [ 'avg_frame_rate', 'r_frame_rate' ]) {
  66     const valuesText: string = videoStream[key]
  67     if (!valuesText) continue
  68
  69     const [ frames, seconds ] = valuesText.split('/')
  70     if (!frames || !seconds) continue
  71
  72     const result = parseInt(frames, 10) / parseInt(seconds, 10)
  73     if (result > 0) return Math.round(result)
  74   }
  75
  76   return 0
  77 }
  78
  79 async function getVideoFileBitrate (path: string) {
  80   return new Promise<number>((res, rej) => {
  81     ffmpeg.ffprobe(path, (err, metadata) => {
  82       if (err) return rej(err)
  83
  84       return res(metadata.format.bit_rate)
  85     })
  86   })
  87 }
  88
  89 function getDurationFromVideoFile (path: string) {
  90   return new Promise<number>((res, rej) => {
  91     ffmpeg.ffprobe(path, (err, metadata) => {
  92       if (err) return rej(err)
  93
  94       return res(Math.floor(metadata.format.duration))
  95     })
  96   })
  97 }
  98
  99 async function generateImageFromVideoFile (fromPath: string, folder: string, imageName: string, size: { width: number, height: number }) {
 100   const pendingImageName = 'pending-' + imageName
 101
 102   const options = {
 103     filename: pendingImageName,
 104     count: 1,
 105     folder
 106   }
 107
 108   const pendingImagePath = join(folder, pendingImageName)
 109
 110   try {
 111     await new Promise<string>((res, rej) => {
 112       ffmpeg(fromPath, { niceness: FFMPEG_NICE.THUMBNAIL })
 113         .on('error', rej)
 114         .on('end', () => res(imageName))
 115         .thumbnail(options)
 116     })
 117
 118     const destination = join(folder, imageName)
 119     await processImage(pendingImagePath, destination, size)
 120   } catch (err) {
 121     logger.error('Cannot generate image from video %s.', fromPath, { err })
 122
 123     try {
 124       await remove(pendingImagePath)
 125     } catch (err) {
 126       logger.debug('Cannot remove pending image path after generation error.', { err })
 127     }
 128   }
 129 }
 130
 131 type TranscodeOptionsType = 'hls' | 'quick-transcode' | 'video' | 'merge-audio' | 'split-audio'
 132
 133 interface BaseTranscodeOptions {
 134   type: TranscodeOptionsType
 135   inputPath: string
 136   outputPath: string
 137   resolution: VideoResolution
 138   isPortraitMode?: boolean
 139 }
 140
 141 interface HLSTranscodeOptions extends BaseTranscodeOptions {
 142   type: 'hls'
 143   copyCodecs: boolean
 144   hlsPlaylist: {
 145     videoFilename: string
 146   }
 147 }
 148
 149 interface QuickTranscodeOptions extends BaseTranscodeOptions {
 150   type: 'quick-transcode'
 151 }
 152
 153 interface VideoTranscodeOptions extends BaseTranscodeOptions {
 154   type: 'video'
 155 }
 156
 157 interface MergeAudioTranscodeOptions extends BaseTranscodeOptions {
 158   type: 'merge-audio'
 159   audioPath: string
 160 }
 161
 162 interface SplitAudioTranscodeOptions extends BaseTranscodeOptions {
 163   type: 'split-audio'
 164 }
 165
 166 type TranscodeOptions = HLSTranscodeOptions | VideoTranscodeOptions | MergeAudioTranscodeOptions | SplitAudioTranscodeOptions | QuickTranscodeOptions
 167
 168 function transcode (options: TranscodeOptions) {
 169   return new Promise<void>(async (res, rej) => {
 170     try {
 171       let command = ffmpeg(options.inputPath, { niceness: FFMPEG_NICE.TRANSCODING })
 172         .output(options.outputPath)
 173
 174       if (options.type === 'quick-transcode') {
 175         command = await buildQuickTranscodeCommand(command)
 176       } else if (options.type === 'hls') {
 177         command = await buildHLSCommand(command, options)
 178       } else if (options.type === 'merge-audio') {
 179         command = await buildAudioMergeCommand(command, options)
 180       } else if (options.type === 'split-audio') {
 181         command = await buildAudioSplitCommand(command, options)
 182       } else {
 183         command = await buildx264Command(command, options)
 184       }
 185
 186       if (CONFIG.TRANSCODING.THREADS > 0) {
 187         // if we don't set any threads ffmpeg will chose automatically
 188         command = command.outputOption('-threads ' + CONFIG.TRANSCODING.THREADS)
 189       }
 190
 191       command
 192         .on('error', (err, stdout, stderr) => {
 193           logger.error('Error in transcoding job.', { stdout, stderr })
 194           return rej(err)
 195         })
 196         .on('end', () => {
 197           return fixHLSPlaylistIfNeeded(options)
 198             .then(() => res())
 199             .catch(err => rej(err))
 200         })
 201         .run()
 202     } catch (err) {
 203       return rej(err)
 204     }
 205   })
 206 }
 207
 208 async function canDoQuickTranscode (path: string): Promise<boolean> {
 209   // NOTE: This could be optimized by running ffprobe only once (but it runs fast anyway)
 210   const videoStream = await getVideoStreamFromFile(path)
 211   const parsedAudio = await audio.get(path)
 212   const fps = await getVideoFileFPS(path)
 213   const bitRate = await getVideoFileBitrate(path)
 214   const resolution = await getVideoFileResolution(path)
 215
 216   // check video params
 217   if (videoStream == null) return false
 218   if (videoStream[ 'codec_name' ] !== 'h264') return false
 219   if (videoStream[ 'pix_fmt' ] !== 'yuv420p') return false
 220   if (fps < VIDEO_TRANSCODING_FPS.MIN || fps > VIDEO_TRANSCODING_FPS.MAX) return false
 221   if (bitRate > getMaxBitrate(resolution.videoFileResolution, fps, VIDEO_TRANSCODING_FPS)) return false
 222
 223     // check audio params (if audio stream exists)
 224   if (parsedAudio.audioStream) {
 225     if (parsedAudio.audioStream[ 'codec_name' ] !== 'aac') return false
 226
 227     const maxAudioBitrate = audio.bitrate[ 'aac' ](parsedAudio.audioStream[ 'bit_rate' ])
 228     if (maxAudioBitrate !== -1 && parsedAudio.audioStream[ 'bit_rate' ] > maxAudioBitrate) return false
 229   }
 230
 231   return true
 232 }
 233
 234 // ---------------------------------------------------------------------------
 235
 236 export {
 237   getVideoFileSize,
 238   getVideoFileResolution,
 239   getDurationFromVideoFile,
 240   generateImageFromVideoFile,
 241   TranscodeOptions,
 242   TranscodeOptionsType,
 243   transcode,
 244   getVideoFileFPS,
 245   computeResolutionsToTranscode,
 246   audio,
 247   getVideoFileBitrate,
 248   canDoQuickTranscode
 249 }
 250
 251 // ---------------------------------------------------------------------------
 252
 253 async function buildx264Command (command: ffmpeg.FfmpegCommand, options: TranscodeOptions) {
 254   let fps = await getVideoFileFPS(options.inputPath)
 255   // On small/medium resolutions, limit FPS
 256   if (
 257     options.resolution !== undefined &&
 258     options.resolution < VIDEO_TRANSCODING_FPS.KEEP_ORIGIN_FPS_RESOLUTION_MIN &&
 259     fps > VIDEO_TRANSCODING_FPS.AVERAGE
 260   ) {
 261     fps = VIDEO_TRANSCODING_FPS.AVERAGE
 262   }
 263
 264   command = await presetH264(command, options.inputPath, options.resolution, fps)
 265
 266   if (options.resolution !== undefined) {
 267     // '?x720' or '720x?' for example
 268     const size = options.isPortraitMode === true ? `${options.resolution}x?` : `?x${options.resolution}`
 269     command = command.size(size)
 270   }
 271
 272   if (fps) {
 273     // Hard FPS limits
 274     if (fps > VIDEO_TRANSCODING_FPS.MAX) fps = VIDEO_TRANSCODING_FPS.MAX
 275     else if (fps < VIDEO_TRANSCODING_FPS.MIN) fps = VIDEO_TRANSCODING_FPS.MIN
 276
 277     command = command.withFPS(fps)
 278   }
 279
 280   return command
 281 }
 282
 283 async function buildAudioMergeCommand (command: ffmpeg.FfmpegCommand, options: MergeAudioTranscodeOptions) {
 284   command = command.loop(undefined)
 285
 286   command = await presetH264VeryFast(command, options.audioPath, options.resolution)
 287
 288   command = command.input(options.audioPath)
 289                    .videoFilter('scale=trunc(iw/2)*2:trunc(ih/2)*2') // Avoid "height not divisible by 2" error
 290                    .outputOption('-tune stillimage')
 291                    .outputOption('-shortest')
 292
 293   return command
 294 }
 295
 296 async function buildAudioSplitCommand (command: ffmpeg.FfmpegCommand, options: SplitAudioTranscodeOptions) {
 297   command = await presetAudioSplit(command)
 298
 299   return command
 300 }
 301
 302 async function buildQuickTranscodeCommand (command: ffmpeg.FfmpegCommand) {
 303   command = await presetCopy(command)
 304
 305   command = command.outputOption('-map_metadata -1') // strip all metadata
 306                    .outputOption('-movflags faststart')
 307
 308   return command
 309 }
 310
 311 async function buildHLSCommand (command: ffmpeg.FfmpegCommand, options: HLSTranscodeOptions) {
 312   const videoPath = getHLSVideoPath(options)
 313
 314   if (options.copyCodecs) command = await presetCopy(command)
 315   else command = await buildx264Command(command, options)
 316
 317   command = command.outputOption('-hls_time 4')
 318                    .outputOption('-hls_list_size 0')
 319                    .outputOption('-hls_playlist_type vod')
 320                    .outputOption('-hls_segment_filename ' + videoPath)
 321                    .outputOption('-hls_segment_type fmp4')
 322                    .outputOption('-f hls')
 323                    .outputOption('-hls_flags single_file')
 324
 325   return command
 326 }
 327
 328 function getHLSVideoPath (options: HLSTranscodeOptions) {
 329   return `${dirname(options.outputPath)}/${options.hlsPlaylist.videoFilename}`
 330 }
 331
 332 async function fixHLSPlaylistIfNeeded (options: TranscodeOptions) {
 333   if (options.type !== 'hls') return
 334
 335   const fileContent = await readFile(options.outputPath)
 336
 337   const videoFileName = options.hlsPlaylist.videoFilename
 338   const videoFilePath = getHLSVideoPath(options)
 339
 340   // Fix wrong mapping with some ffmpeg versions
 341   const newContent = fileContent.toString()
 342                                 .replace(`#EXT-X-MAP:URI="${videoFilePath}",`, `#EXT-X-MAP:URI="${videoFileName}",`)
 343
 344   await writeFile(options.outputPath, newContent)
 345 }
 346
 347 function getVideoStreamFromFile (path: string) {
 348   return new Promise<any>((res, rej) => {
 349     ffmpeg.ffprobe(path, (err, metadata) => {
 350       if (err) return rej(err)
 351
 352       const videoStream = metadata.streams.find(s => s.codec_type === 'video')
 353       //if (!videoStream) return rej(new Error('Cannot find video stream of ' + path))
 354
 355       return res(videoStream)
 356     })
 357   })
 358 }
 359
 360 /**
 361  * A slightly customised version of the 'veryfast' x264 preset
 362  *
 363  * The veryfast preset is right in the sweet spot of performance
 364  * and quality. Superfast and ultrafast will give you better
 365  * performance, but then quality is noticeably worse.
 366  */
 367 async function presetH264VeryFast (command: ffmpeg.FfmpegCommand, input: string, resolution: VideoResolution, fps?: number) {
 368   let localCommand = await presetH264(command, input, resolution, fps)
 369
 370   localCommand = localCommand.outputOption('-preset:v veryfast')
 371
 372   /*
 373   MAIN reference: https://slhck.info/video/2017/03/01/rate-control.html
 374   Our target situation is closer to a livestream than a stream,
 375   since we want to reduce as much a possible the encoding burden,
 376   although not to the point of a livestream where there is a hard
 377   constraint on the frames per second to be encoded.
 378   */
 379
 380   return localCommand
 381 }
 382
 383 /**
 384  * A toolbox to play with audio
 385  */
 386 namespace audio {
 387   export const get = (option: string) => {
 388     // without position, ffprobe considers the last input only
 389     // we make it consider the first input only
 390     // if you pass a file path to pos, then ffprobe acts on that file directly
 391     return new Promise<{ absolutePath: string, audioStream?: any }>((res, rej) => {
 392
 393       function parseFfprobe (err: any, data: ffmpeg.FfprobeData) {
 394         if (err) return rej(err)
 395
 396         if ('streams' in data) {
 397           const audioStream = data.streams.find(stream => stream['codec_type'] === 'audio')
 398           if (audioStream) {
 399             return res({
 400               absolutePath: data.format.filename,
 401               audioStream
 402             })
 403           }
 404         }
 405
 406         return res({ absolutePath: data.format.filename })
 407       }
 408
 409       return ffmpeg.ffprobe(option, parseFfprobe)
 410     })
 411   }
 412
 413   export namespace bitrate {
 414     const baseKbitrate = 384
 415
 416     const toBits = (kbits: number) => kbits * 8000
 417
 418     export const aac = (bitrate: number): number => {
 419       switch (true) {
 420         case bitrate > toBits(baseKbitrate):
 421           return baseKbitrate
 422
 423         default:
 424           return -1 // we interpret it as a signal to copy the audio stream as is
 425       }
 426     }
 427
 428     export const mp3 = (bitrate: number): number => {
 429       /*
 430       a 192kbit/sec mp3 doesn't hold as much information as a 192kbit/sec aac.
 431       That's why, when using aac, we can go to lower kbit/sec. The equivalences
 432       made here are not made to be accurate, especially with good mp3 encoders.
 433       */
 434       switch (true) {
 435         case bitrate <= toBits(192):
 436           return 128
 437
 438         case bitrate <= toBits(384):
 439           return 256
 440
 441         default:
 442           return baseKbitrate
 443       }
 444     }
 445   }
 446 }
 447
 448 /**
 449  * Standard profile, with variable bitrate audio and faststart.
 450  *
 451  * As for the audio, quality '5' is the highest and ensures 96-112kbps/channel
 452  * See https://trac.ffmpeg.org/wiki/Encode/AAC#fdk_vbr
 453  */
 454 async function presetH264 (command: ffmpeg.FfmpegCommand, input: string, resolution: VideoResolution, fps?: number) {
 455   let localCommand = command
 456     .format('mp4')
 457     .videoCodec('libx264')
 458     .outputOption('-level 3.1') // 3.1 is the minimal ressource allocation for our highest supported resolution
 459     .outputOption('-b_strategy 1') // NOTE: b-strategy 1 - heuristic algorythm, 16 is optimal B-frames for it
 460     .outputOption('-bf 16') // NOTE: Why 16: https://github.com/Chocobozzz/PeerTube/pull/774. b-strategy 2 -> B-frames<16
 461     .outputOption('-pix_fmt yuv420p') // allows import of source material with incompatible pixel formats (e.g. MJPEG video)
 462     .outputOption('-map_metadata -1') // strip all metadata
 463     .outputOption('-movflags faststart')
 464
 465   const parsedAudio = await audio.get(input)
 466
 467   if (!parsedAudio.audioStream) {
 468     localCommand = localCommand.noAudio()
 469   } else if ((await checkFFmpegEncoders()).get('libfdk_aac')) { // we favor VBR, if a good AAC encoder is available
 470     localCommand = localCommand
 471       .audioCodec('libfdk_aac')
 472       .audioQuality(5)
 473   } else {
 474     // we try to reduce the ceiling bitrate by making rough matches of bitrates
 475     // of course this is far from perfect, but it might save some space in the end
 476     localCommand = localCommand.audioCodec('aac')
 477
 478     const audioCodecName = parsedAudio.audioStream[ 'codec_name' ]
 479
 480     if (audio.bitrate[ audioCodecName ]) {
 481       const bitrate = audio.bitrate[ audioCodecName ](parsedAudio.audioStream[ 'bit_rate' ])
 482       if (bitrate !== undefined && bitrate !== -1) localCommand = localCommand.audioBitrate(bitrate)
 483     }
 484   }
 485
 486   if (fps) {
 487     // Constrained Encoding (VBV)
 488     // https://slhck.info/video/2017/03/01/rate-control.html
 489     // https://trac.ffmpeg.org/wiki/Limiting%20the%20output%20bitrate
 490     const targetBitrate = getTargetBitrate(resolution, fps, VIDEO_TRANSCODING_FPS)
 491     localCommand = localCommand.outputOptions([ `-maxrate ${targetBitrate}`, `-bufsize ${targetBitrate * 2}` ])
 492
 493     // Keyframe interval of 2 seconds for faster seeking and resolution switching.
 494     // https://streaminglearningcenter.com/blogs/whats-the-right-keyframe-interval.html
 495     // https://superuser.com/a/908325
 496     localCommand = localCommand.outputOption(`-g ${fps * 2}`)
 497   }
 498
 499   return localCommand
 500 }
 501
 502 async function presetCopy (command: ffmpeg.FfmpegCommand): Promise<ffmpeg.FfmpegCommand> {
 503   return command
 504     .format('mp4')
 505     .videoCodec('copy')
 506     .audioCodec('copy')
 507 }
 508
 509
 510 async function presetAudioSplit (command: ffmpeg.FfmpegCommand): Promise<ffmpeg.FfmpegCommand> {
 511   return command
 512     .format('mp4')
 513     .audioCodec('copy')
 514     .noVideo()
 515 }