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