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 } 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 fps = await getVideoFileFPS(options.inputPath)
 134       // On small/medium resolutions, limit FPS
 135       if (
 136         options.resolution !== undefined &&
 137         options.resolution < VIDEO_TRANSCODING_FPS.KEEP_ORIGIN_FPS_RESOLUTION_MIN &&
 138         fps > VIDEO_TRANSCODING_FPS.AVERAGE
 139       ) {
 140         fps = VIDEO_TRANSCODING_FPS.AVERAGE
 141       }
 142
 143       let command = ffmpeg(options.inputPath, { niceness: FFMPEG_NICE.TRANSCODING })
 144         .output(options.outputPath)
 145       command = await presetH264(command, options.resolution, fps)
 146
 147       if (CONFIG.TRANSCODING.THREADS > 0) {
 148         // if we don't set any threads ffmpeg will chose automatically
 149         command = command.outputOption('-threads ' + CONFIG.TRANSCODING.THREADS)
 150       }
 151
 152       if (options.resolution !== undefined) {
 153         // '?x720' or '720x?' for example
 154         const size = options.isPortraitMode === true ? `${options.resolution}x?` : `?x${options.resolution}`
 155         command = command.size(size)
 156       }
 157
 158       if (fps) {
 159         // Hard FPS limits
 160         if (fps > VIDEO_TRANSCODING_FPS.MAX) fps = VIDEO_TRANSCODING_FPS.MAX
 161         else if (fps < VIDEO_TRANSCODING_FPS.MIN) fps = VIDEO_TRANSCODING_FPS.MIN
 162
 163         command = command.withFPS(fps)
 164       }
 165
 166       if (options.hlsPlaylist) {
 167         const videoPath = `${dirname(options.outputPath)}/${options.hlsPlaylist.videoFilename}`
 168
 169         command = command.outputOption('-hls_time 4')
 170                          .outputOption('-hls_list_size 0')
 171                          .outputOption('-hls_playlist_type vod')
 172                          .outputOption('-hls_segment_filename ' + videoPath)
 173                          .outputOption('-hls_segment_type fmp4')
 174                          .outputOption('-f hls')
 175                          .outputOption('-hls_flags single_file')
 176       }
 177
 178       command
 179         .on('error', (err, stdout, stderr) => {
 180           logger.error('Error in transcoding job.', { stdout, stderr })
 181           return rej(err)
 182         })
 183         .on('end', res)
 184         .run()
 185     } catch (err) {
 186       return rej(err)
 187     }
 188   })
 189 }
 190
 191 // ---------------------------------------------------------------------------
 192
 193 export {
 194   getVideoFileSize,
 195   getVideoFileResolution,
 196   getDurationFromVideoFile,
 197   generateImageFromVideoFile,
 198   transcode,
 199   getVideoFileFPS,
 200   computeResolutionsToTranscode,
 201   audio,
 202   getVideoFileBitrate
 203 }
 204
 205 // ---------------------------------------------------------------------------
 206
 207 function getVideoFileStream (path: string) {
 208   return new Promise<any>((res, rej) => {
 209     ffmpeg.ffprobe(path, (err, metadata) => {
 210       if (err) return rej(err)
 211
 212       const videoStream = metadata.streams.find(s => s.codec_type === 'video')
 213       if (!videoStream) return rej(new Error('Cannot find video stream of ' + path))
 214
 215       return res(videoStream)
 216     })
 217   })
 218 }
 219
 220 /**
 221  * A slightly customised version of the 'veryfast' x264 preset
 222  *
 223  * The veryfast preset is right in the sweet spot of performance
 224  * and quality. Superfast and ultrafast will give you better
 225  * performance, but then quality is noticeably worse.
 226  */
 227 async function presetH264VeryFast (command: ffmpeg.FfmpegCommand, resolution: VideoResolution, fps: number): Promise<ffmpeg.FfmpegCommand> {
 228   let localCommand = await presetH264(command, resolution, fps)
 229   localCommand = localCommand.outputOption('-preset:v veryfast')
 230              .outputOption([ '--aq-mode=2', '--aq-strength=1.3' ])
 231   /*
 232   MAIN reference: https://slhck.info/video/2017/03/01/rate-control.html
 233   Our target situation is closer to a livestream than a stream,
 234   since we want to reduce as much a possible the encoding burden,
 235   altough not to the point of a livestream where there is a hard
 236   constraint on the frames per second to be encoded.
 237
 238   why '--aq-mode=2 --aq-strength=1.3' instead of '-profile:v main'?
 239     Make up for most of the loss of grain and macroblocking
 240     with less computing power.
 241   */
 242
 243   return localCommand
 244 }
 245
 246 /**
 247  * A preset optimised for a stillimage audio video
 248  */
 249 async function presetStillImageWithAudio (
 250   command: ffmpeg.FfmpegCommand,
 251   resolution: VideoResolution,
 252   fps: number
 253 ): Promise<ffmpeg.FfmpegCommand> {
 254   let localCommand = await presetH264VeryFast(command, resolution, fps)
 255   localCommand = localCommand.outputOption('-tune stillimage')
 256
 257   return localCommand
 258 }
 259
 260 /**
 261  * A toolbox to play with audio
 262  */
 263 namespace audio {
 264   export const get = (option: ffmpeg.FfmpegCommand | string) => {
 265     // without position, ffprobe considers the last input only
 266     // we make it consider the first input only
 267     // if you pass a file path to pos, then ffprobe acts on that file directly
 268     return new Promise<{ absolutePath: string, audioStream?: any }>((res, rej) => {
 269
 270       function parseFfprobe (err: any, data: ffmpeg.FfprobeData) {
 271         if (err) return rej(err)
 272
 273         if ('streams' in data) {
 274           const audioStream = data.streams.find(stream => stream['codec_type'] === 'audio')
 275           if (audioStream) {
 276             return res({
 277               absolutePath: data.format.filename,
 278               audioStream
 279             })
 280           }
 281         }
 282
 283         return res({ absolutePath: data.format.filename })
 284       }
 285
 286       if (typeof option === 'string') {
 287         return ffmpeg.ffprobe(option, parseFfprobe)
 288       }
 289
 290       return option.ffprobe(parseFfprobe)
 291     })
 292   }
 293
 294   export namespace bitrate {
 295     const baseKbitrate = 384
 296
 297     const toBits = (kbits: number): number => { return kbits * 8000 }
 298
 299     export const aac = (bitrate: number): number => {
 300       switch (true) {
 301       case bitrate > toBits(baseKbitrate):
 302         return baseKbitrate
 303       default:
 304         return -1 // we interpret it as a signal to copy the audio stream as is
 305       }
 306     }
 307
 308     export const mp3 = (bitrate: number): number => {
 309       /*
 310       a 192kbit/sec mp3 doesn't hold as much information as a 192kbit/sec aac.
 311       That's why, when using aac, we can go to lower kbit/sec. The equivalences
 312       made here are not made to be accurate, especially with good mp3 encoders.
 313       */
 314       switch (true) {
 315       case bitrate <= toBits(192):
 316         return 128
 317       case bitrate <= toBits(384):
 318         return 256
 319       default:
 320         return baseKbitrate
 321       }
 322     }
 323   }
 324 }
 325
 326 /**
 327  * Standard profile, with variable bitrate audio and faststart.
 328  *
 329  * As for the audio, quality '5' is the highest and ensures 96-112kbps/channel
 330  * See https://trac.ffmpeg.org/wiki/Encode/AAC#fdk_vbr
 331  */
 332 async function presetH264 (command: ffmpeg.FfmpegCommand, resolution: VideoResolution, fps: number): Promise<ffmpeg.FfmpegCommand> {
 333   let localCommand = command
 334     .format('mp4')
 335     .videoCodec('libx264')
 336     .outputOption('-level 3.1') // 3.1 is the minimal ressource allocation for our highest supported resolution
 337     .outputOption('-b_strategy 1') // NOTE: b-strategy 1 - heuristic algorythm, 16 is optimal B-frames for it
 338     .outputOption('-bf 16') // NOTE: Why 16: https://github.com/Chocobozzz/PeerTube/pull/774. b-strategy 2 -> B-frames<16
 339     .outputOption('-pix_fmt yuv420p') // allows import of source material with incompatible pixel formats (e.g. MJPEG video)
 340     .outputOption('-map_metadata -1') // strip all metadata
 341     .outputOption('-movflags faststart')
 342
 343   const parsedAudio = await audio.get(localCommand)
 344
 345   if (!parsedAudio.audioStream) {
 346     localCommand = localCommand.noAudio()
 347   } else if ((await checkFFmpegEncoders()).get('libfdk_aac')) { // we favor VBR, if a good AAC encoder is available
 348     localCommand = localCommand
 349       .audioCodec('libfdk_aac')
 350       .audioQuality(5)
 351   } else {
 352     // we try to reduce the ceiling bitrate by making rough correspondances of bitrates
 353     // of course this is far from perfect, but it might save some space in the end
 354     const audioCodecName = parsedAudio.audioStream[ 'codec_name' ]
 355     let bitrate: number
 356     if (audio.bitrate[ audioCodecName ]) {
 357       localCommand = localCommand.audioCodec('aac')
 358
 359       bitrate = audio.bitrate[ audioCodecName ](parsedAudio.audioStream[ 'bit_rate' ])
 360       if (bitrate !== undefined && bitrate !== -1) localCommand = localCommand.audioBitrate(bitrate)
 361     }
 362   }
 363
 364   // Constrained Encoding (VBV)
 365   // https://slhck.info/video/2017/03/01/rate-control.html
 366   // https://trac.ffmpeg.org/wiki/Limiting%20the%20output%20bitrate
 367   const targetBitrate = getTargetBitrate(resolution, fps, VIDEO_TRANSCODING_FPS)
 368   localCommand = localCommand.outputOptions([`-maxrate ${ targetBitrate }`, `-bufsize ${ targetBitrate * 2 }`])
 369
 370   // Keyframe interval of 2 seconds for faster seeking and resolution switching.
 371   // https://streaminglearningcenter.com/blogs/whats-the-right-keyframe-interval.html
 372   // https://superuser.com/a/908325
 373   localCommand = localCommand.outputOption(`-g ${ fps * 2 }`)
 374
 375   return localCommand
 376 }