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