server/helpers/ffmpeg-utils.ts

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