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 (videoStream[ 'pix_fmt' ] !== 'yuv420p') return false
 202   if (fps < VIDEO_TRANSCODING_FPS.MIN || fps > VIDEO_TRANSCODING_FPS.MAX) return false
 203   if (bitRate > getMaxBitrate(resolution.videoFileResolution, fps, VIDEO_TRANSCODING_FPS)) return false
 204
 205     // check audio params (if audio stream exists)
 206   if (parsedAudio.audioStream) {
 207     if (parsedAudio.audioStream[ 'codec_name' ] !== 'aac') return false
 208
 209     const maxAudioBitrate = audio.bitrate[ 'aac' ](parsedAudio.audioStream[ 'bit_rate' ])
 210     if (maxAudioBitrate !== -1 && parsedAudio.audioStream[ 'bit_rate' ] > maxAudioBitrate) return false
 211   }
 212
 213   return true
 214 }
 215
 216 // ---------------------------------------------------------------------------
 217
 218 export {
 219   getVideoFileSize,
 220   getVideoFileResolution,
 221   getDurationFromVideoFile,
 222   generateImageFromVideoFile,
 223   TranscodeOptions,
 224   TranscodeOptionsType,
 225   transcode,
 226   getVideoFileFPS,
 227   computeResolutionsToTranscode,
 228   audio,
 229   getVideoFileBitrate,
 230   canDoQuickTranscode
 231 }
 232
 233 // ---------------------------------------------------------------------------
 234
 235 async function buildx264Command (command: ffmpeg.FfmpegCommand, options: VideoTranscodeOptions) {
 236   let fps = await getVideoFileFPS(options.inputPath)
 237   // On small/medium resolutions, limit FPS
 238   if (
 239     options.resolution !== undefined &&
 240     options.resolution < VIDEO_TRANSCODING_FPS.KEEP_ORIGIN_FPS_RESOLUTION_MIN &&
 241     fps > VIDEO_TRANSCODING_FPS.AVERAGE
 242   ) {
 243     fps = VIDEO_TRANSCODING_FPS.AVERAGE
 244   }
 245
 246   command = await presetH264(command, options.inputPath, options.resolution, fps)
 247
 248   if (options.resolution !== undefined) {
 249     // '?x720' or '720x?' for example
 250     const size = options.isPortraitMode === true ? `${options.resolution}x?` : `?x${options.resolution}`
 251     command = command.size(size)
 252   }
 253
 254   if (fps) {
 255     // Hard FPS limits
 256     if (fps > VIDEO_TRANSCODING_FPS.MAX) fps = VIDEO_TRANSCODING_FPS.MAX
 257     else if (fps < VIDEO_TRANSCODING_FPS.MIN) fps = VIDEO_TRANSCODING_FPS.MIN
 258
 259     command = command.withFPS(fps)
 260   }
 261
 262   return command
 263 }
 264
 265 async function buildAudioMergeCommand (command: ffmpeg.FfmpegCommand, options: MergeAudioTranscodeOptions) {
 266   command = command.loop(undefined)
 267
 268   command = await presetH264VeryFast(command, options.audioPath, options.resolution)
 269
 270   command = command.input(options.audioPath)
 271                    .videoFilter('scale=trunc(iw/2)*2:trunc(ih/2)*2') // Avoid "height not divisible by 2" error
 272                    .outputOption('-tune stillimage')
 273                    .outputOption('-shortest')
 274
 275   return command
 276 }
 277
 278 async function buildQuickTranscodeCommand (command: ffmpeg.FfmpegCommand) {
 279   command = await presetCopy(command)
 280
 281   command = command.outputOption('-map_metadata -1') // strip all metadata
 282                    .outputOption('-movflags faststart')
 283
 284   return command
 285 }
 286
 287 async function buildHLSCommand (command: ffmpeg.FfmpegCommand, options: HLSTranscodeOptions) {
 288   const videoPath = getHLSVideoPath(options)
 289
 290   command = await presetCopy(command)
 291
 292   command = command.outputOption('-hls_time 4')
 293                    .outputOption('-hls_list_size 0')
 294                    .outputOption('-hls_playlist_type vod')
 295                    .outputOption('-hls_segment_filename ' + videoPath)
 296                    .outputOption('-hls_segment_type fmp4')
 297                    .outputOption('-f hls')
 298                    .outputOption('-hls_flags single_file')
 299
 300   return command
 301 }
 302
 303 function getHLSVideoPath (options: HLSTranscodeOptions) {
 304   return `${dirname(options.outputPath)}/${options.hlsPlaylist.videoFilename}`
 305 }
 306
 307 async function fixHLSPlaylistIfNeeded (options: TranscodeOptions) {
 308   if (options.type !== 'hls') return
 309
 310   const fileContent = await readFile(options.outputPath)
 311
 312   const videoFileName = options.hlsPlaylist.videoFilename
 313   const videoFilePath = getHLSVideoPath(options)
 314
 315   // Fix wrong mapping with some ffmpeg versions
 316   const newContent = fileContent.toString()
 317                                 .replace(`#EXT-X-MAP:URI="${videoFilePath}",`, `#EXT-X-MAP:URI="${videoFileName}",`)
 318
 319   await writeFile(options.outputPath, newContent)
 320 }
 321
 322 function getVideoStreamFromFile (path: string) {
 323   return new Promise<any>((res, rej) => {
 324     ffmpeg.ffprobe(path, (err, metadata) => {
 325       if (err) return rej(err)
 326
 327       const videoStream = metadata.streams.find(s => s.codec_type === 'video')
 328       if (!videoStream) return rej(new Error('Cannot find video stream of ' + path))
 329
 330       return res(videoStream)
 331     })
 332   })
 333 }
 334
 335 /**
 336  * A slightly customised version of the 'veryfast' x264 preset
 337  *
 338  * The veryfast preset is right in the sweet spot of performance
 339  * and quality. Superfast and ultrafast will give you better
 340  * performance, but then quality is noticeably worse.
 341  */
 342 async function presetH264VeryFast (command: ffmpeg.FfmpegCommand, input: string, resolution: VideoResolution, fps?: number) {
 343   let localCommand = await presetH264(command, input, resolution, fps)
 344
 345   localCommand = localCommand.outputOption('-preset:v veryfast')
 346
 347   /*
 348   MAIN reference: https://slhck.info/video/2017/03/01/rate-control.html
 349   Our target situation is closer to a livestream than a stream,
 350   since we want to reduce as much a possible the encoding burden,
 351   although not to the point of a livestream where there is a hard
 352   constraint on the frames per second to be encoded.
 353   */
 354
 355   return localCommand
 356 }
 357
 358 /**
 359  * A toolbox to play with audio
 360  */
 361 namespace audio {
 362   export const get = (option: string) => {
 363     // without position, ffprobe considers the last input only
 364     // we make it consider the first input only
 365     // if you pass a file path to pos, then ffprobe acts on that file directly
 366     return new Promise<{ absolutePath: string, audioStream?: any }>((res, rej) => {
 367
 368       function parseFfprobe (err: any, data: ffmpeg.FfprobeData) {
 369         if (err) return rej(err)
 370
 371         if ('streams' in data) {
 372           const audioStream = data.streams.find(stream => stream['codec_type'] === 'audio')
 373           if (audioStream) {
 374             return res({
 375               absolutePath: data.format.filename,
 376               audioStream
 377             })
 378           }
 379         }
 380
 381         return res({ absolutePath: data.format.filename })
 382       }
 383
 384       return ffmpeg.ffprobe(option, parseFfprobe)
 385     })
 386   }
 387
 388   export namespace bitrate {
 389     const baseKbitrate = 384
 390
 391     const toBits = (kbits: number) => kbits * 8000
 392
 393     export const aac = (bitrate: number): number => {
 394       switch (true) {
 395         case bitrate > toBits(baseKbitrate):
 396           return baseKbitrate
 397
 398         default:
 399           return -1 // we interpret it as a signal to copy the audio stream as is
 400       }
 401     }
 402
 403     export const mp3 = (bitrate: number): number => {
 404       /*
 405       a 192kbit/sec mp3 doesn't hold as much information as a 192kbit/sec aac.
 406       That's why, when using aac, we can go to lower kbit/sec. The equivalences
 407       made here are not made to be accurate, especially with good mp3 encoders.
 408       */
 409       switch (true) {
 410         case bitrate <= toBits(192):
 411           return 128
 412
 413         case bitrate <= toBits(384):
 414           return 256
 415
 416         default:
 417           return baseKbitrate
 418       }
 419     }
 420   }
 421 }
 422
 423 /**
 424  * Standard profile, with variable bitrate audio and faststart.
 425  *
 426  * As for the audio, quality '5' is the highest and ensures 96-112kbps/channel
 427  * See https://trac.ffmpeg.org/wiki/Encode/AAC#fdk_vbr
 428  */
 429 async function presetH264 (command: ffmpeg.FfmpegCommand, input: string, resolution: VideoResolution, fps?: number) {
 430   let localCommand = command
 431     .format('mp4')
 432     .videoCodec('libx264')
 433     .outputOption('-level 3.1') // 3.1 is the minimal ressource allocation for our highest supported resolution
 434     .outputOption('-b_strategy 1') // NOTE: b-strategy 1 - heuristic algorythm, 16 is optimal B-frames for it
 435     .outputOption('-bf 16') // NOTE: Why 16: https://github.com/Chocobozzz/PeerTube/pull/774. b-strategy 2 -> B-frames<16
 436     .outputOption('-pix_fmt yuv420p') // allows import of source material with incompatible pixel formats (e.g. MJPEG video)
 437     .outputOption('-map_metadata -1') // strip all metadata
 438     .outputOption('-movflags faststart')
 439
 440   const parsedAudio = await audio.get(input)
 441
 442   if (!parsedAudio.audioStream) {
 443     localCommand = localCommand.noAudio()
 444   } else if ((await checkFFmpegEncoders()).get('libfdk_aac')) { // we favor VBR, if a good AAC encoder is available
 445     localCommand = localCommand
 446       .audioCodec('libfdk_aac')
 447       .audioQuality(5)
 448   } else {
 449     // we try to reduce the ceiling bitrate by making rough matches of bitrates
 450     // of course this is far from perfect, but it might save some space in the end
 451     localCommand = localCommand.audioCodec('aac')
 452
 453     const audioCodecName = parsedAudio.audioStream[ 'codec_name' ]
 454
 455     if (audio.bitrate[ audioCodecName ]) {
 456       const bitrate = audio.bitrate[ audioCodecName ](parsedAudio.audioStream[ 'bit_rate' ])
 457       if (bitrate !== undefined && bitrate !== -1) localCommand = localCommand.audioBitrate(bitrate)
 458     }
 459   }
 460
 461   if (fps) {
 462     // Constrained Encoding (VBV)
 463     // https://slhck.info/video/2017/03/01/rate-control.html
 464     // https://trac.ffmpeg.org/wiki/Limiting%20the%20output%20bitrate
 465     const targetBitrate = getTargetBitrate(resolution, fps, VIDEO_TRANSCODING_FPS)
 466     localCommand = localCommand.outputOptions([ `-maxrate ${targetBitrate}`, `-bufsize ${targetBitrate * 2}` ])
 467
 468     // Keyframe interval of 2 seconds for faster seeking and resolution switching.
 469     // https://streaminglearningcenter.com/blogs/whats-the-right-keyframe-interval.html
 470     // https://superuser.com/a/908325
 471     localCommand = localCommand.outputOption(`-g ${fps * 2}`)
 472   }
 473
 474   return localCommand
 475 }
 476
 477 async function presetCopy (command: ffmpeg.FfmpegCommand): Promise<ffmpeg.FfmpegCommand> {
 478   return command
 479     .format('mp4')
 480     .videoCodec('copy')
 481     .audioCodec('copy')
 482 }