server/helpers/ffmpeg-utils.ts

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