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   generateHlsPlaylist?: boolean
 126 }
 127
 128 function transcode (options: TranscodeOptions) {
 129   return new Promise<void>(async (res, rej) => {
 130     try {
 131       let fps = await getVideoFileFPS(options.inputPath)
 132       // On small/medium resolutions, limit FPS
 133       if (
 134         options.resolution !== undefined &&
 135         options.resolution < VIDEO_TRANSCODING_FPS.KEEP_ORIGIN_FPS_RESOLUTION_MIN &&
 136         fps > VIDEO_TRANSCODING_FPS.AVERAGE
 137       ) {
 138         fps = VIDEO_TRANSCODING_FPS.AVERAGE
 139       }
 140
 141       let command = ffmpeg(options.inputPath, { niceness: FFMPEG_NICE.TRANSCODING })
 142         .output(options.outputPath)
 143       command = await presetH264(command, options.resolution, fps)
 144
 145       if (CONFIG.TRANSCODING.THREADS > 0) {
 146         // if we don't set any threads ffmpeg will chose automatically
 147         command = command.outputOption('-threads ' + CONFIG.TRANSCODING.THREADS)
 148       }
 149
 150       if (options.resolution !== undefined) {
 151         // '?x720' or '720x?' for example
 152         const size = options.isPortraitMode === true ? `${options.resolution}x?` : `?x${options.resolution}`
 153         command = command.size(size)
 154       }
 155
 156       if (fps) {
 157         // Hard FPS limits
 158         if (fps > VIDEO_TRANSCODING_FPS.MAX) fps = VIDEO_TRANSCODING_FPS.MAX
 159         else if (fps < VIDEO_TRANSCODING_FPS.MIN) fps = VIDEO_TRANSCODING_FPS.MIN
 160
 161         command = command.withFPS(fps)
 162       }
 163
 164       if (options.generateHlsPlaylist) {
 165         const segmentFilename = `${dirname(options.outputPath)}/${options.resolution}_%03d.ts`
 166
 167         command = command.outputOption('-hls_time 4')
 168                          .outputOption('-hls_list_size 0')
 169                          .outputOption('-hls_playlist_type vod')
 170                          .outputOption('-hls_segment_filename ' + segmentFilename)
 171                          .outputOption('-f hls')
 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', res)
 180         .run()
 181     } catch (err) {
 182       return rej(err)
 183     }
 184   })
 185 }
 186
 187 // ---------------------------------------------------------------------------
 188
 189 export {
 190   getVideoFileSize,
 191   getVideoFileResolution,
 192   getDurationFromVideoFile,
 193   generateImageFromVideoFile,
 194   transcode,
 195   getVideoFileFPS,
 196   computeResolutionsToTranscode,
 197   audio,
 198   getVideoFileBitrate
 199 }
 200
 201 // ---------------------------------------------------------------------------
 202
 203 function getVideoFileStream (path: string) {
 204   return new Promise<any>((res, rej) => {
 205     ffmpeg.ffprobe(path, (err, metadata) => {
 206       if (err) return rej(err)
 207
 208       const videoStream = metadata.streams.find(s => s.codec_type === 'video')
 209       if (!videoStream) return rej(new Error('Cannot find video stream of ' + path))
 210
 211       return res(videoStream)
 212     })
 213   })
 214 }
 215
 216 /**
 217  * A slightly customised version of the 'veryfast' x264 preset
 218  *
 219  * The veryfast preset is right in the sweet spot of performance
 220  * and quality. Superfast and ultrafast will give you better
 221  * performance, but then quality is noticeably worse.
 222  */
 223 async function presetH264VeryFast (command: ffmpeg.FfmpegCommand, resolution: VideoResolution, fps: number): Promise<ffmpeg.FfmpegCommand> {
 224   let localCommand = await presetH264(command, resolution, fps)
 225   localCommand = localCommand.outputOption('-preset:v veryfast')
 226              .outputOption([ '--aq-mode=2', '--aq-strength=1.3' ])
 227   /*
 228   MAIN reference: https://slhck.info/video/2017/03/01/rate-control.html
 229   Our target situation is closer to a livestream than a stream,
 230   since we want to reduce as much a possible the encoding burden,
 231   altough not to the point of a livestream where there is a hard
 232   constraint on the frames per second to be encoded.
 233
 234   why '--aq-mode=2 --aq-strength=1.3' instead of '-profile:v main'?
 235     Make up for most of the loss of grain and macroblocking
 236     with less computing power.
 237   */
 238
 239   return localCommand
 240 }
 241
 242 /**
 243  * A preset optimised for a stillimage audio video
 244  */
 245 async function presetStillImageWithAudio (
 246   command: ffmpeg.FfmpegCommand,
 247   resolution: VideoResolution,
 248   fps: number
 249 ): Promise<ffmpeg.FfmpegCommand> {
 250   let localCommand = await presetH264VeryFast(command, resolution, fps)
 251   localCommand = localCommand.outputOption('-tune stillimage')
 252
 253   return localCommand
 254 }
 255
 256 /**
 257  * A toolbox to play with audio
 258  */
 259 namespace audio {
 260   export const get = (option: ffmpeg.FfmpegCommand | string) => {
 261     // without position, ffprobe considers the last input only
 262     // we make it consider the first input only
 263     // if you pass a file path to pos, then ffprobe acts on that file directly
 264     return new Promise<{ absolutePath: string, audioStream?: any }>((res, rej) => {
 265
 266       function parseFfprobe (err: any, data: ffmpeg.FfprobeData) {
 267         if (err) return rej(err)
 268
 269         if ('streams' in data) {
 270           const audioStream = data.streams.find(stream => stream['codec_type'] === 'audio')
 271           if (audioStream) {
 272             return res({
 273               absolutePath: data.format.filename,
 274               audioStream
 275             })
 276           }
 277         }
 278
 279         return res({ absolutePath: data.format.filename })
 280       }
 281
 282       if (typeof option === 'string') {
 283         return ffmpeg.ffprobe(option, parseFfprobe)
 284       }
 285
 286       return option.ffprobe(parseFfprobe)
 287     })
 288   }
 289
 290   export namespace bitrate {
 291     const baseKbitrate = 384
 292
 293     const toBits = (kbits: number): number => { return kbits * 8000 }
 294
 295     export const aac = (bitrate: number): number => {
 296       switch (true) {
 297       case bitrate > toBits(baseKbitrate):
 298         return baseKbitrate
 299       default:
 300         return -1 // we interpret it as a signal to copy the audio stream as is
 301       }
 302     }
 303
 304     export const mp3 = (bitrate: number): number => {
 305       /*
 306       a 192kbit/sec mp3 doesn't hold as much information as a 192kbit/sec aac.
 307       That's why, when using aac, we can go to lower kbit/sec. The equivalences
 308       made here are not made to be accurate, especially with good mp3 encoders.
 309       */
 310       switch (true) {
 311       case bitrate <= toBits(192):
 312         return 128
 313       case bitrate <= toBits(384):
 314         return 256
 315       default:
 316         return baseKbitrate
 317       }
 318     }
 319   }
 320 }
 321
 322 /**
 323  * Standard profile, with variable bitrate audio and faststart.
 324  *
 325  * As for the audio, quality '5' is the highest and ensures 96-112kbps/channel
 326  * See https://trac.ffmpeg.org/wiki/Encode/AAC#fdk_vbr
 327  */
 328 async function presetH264 (command: ffmpeg.FfmpegCommand, resolution: VideoResolution, fps: number): Promise<ffmpeg.FfmpegCommand> {
 329   let localCommand = command
 330     .format('mp4')
 331     .videoCodec('libx264')
 332     .outputOption('-level 3.1') // 3.1 is the minimal ressource allocation for our highest supported resolution
 333     .outputOption('-b_strategy 1') // NOTE: b-strategy 1 - heuristic algorythm, 16 is optimal B-frames for it
 334     .outputOption('-bf 16') // NOTE: Why 16: https://github.com/Chocobozzz/PeerTube/pull/774. b-strategy 2 -> B-frames<16
 335     .outputOption('-pix_fmt yuv420p') // allows import of source material with incompatible pixel formats (e.g. MJPEG video)
 336     .outputOption('-map_metadata -1') // strip all metadata
 337     .outputOption('-movflags faststart')
 338
 339   const parsedAudio = await audio.get(localCommand)
 340
 341   if (!parsedAudio.audioStream) {
 342     localCommand = localCommand.noAudio()
 343   } else if ((await checkFFmpegEncoders()).get('libfdk_aac')) { // we favor VBR, if a good AAC encoder is available
 344     localCommand = localCommand
 345       .audioCodec('libfdk_aac')
 346       .audioQuality(5)
 347   } else {
 348     // we try to reduce the ceiling bitrate by making rough correspondances of bitrates
 349     // of course this is far from perfect, but it might save some space in the end
 350     const audioCodecName = parsedAudio.audioStream[ 'codec_name' ]
 351     let bitrate: number
 352     if (audio.bitrate[ audioCodecName ]) {
 353       localCommand = localCommand.audioCodec('aac')
 354
 355       bitrate = audio.bitrate[ audioCodecName ](parsedAudio.audioStream[ 'bit_rate' ])
 356       if (bitrate !== undefined && bitrate !== -1) localCommand = localCommand.audioBitrate(bitrate)
 357     }
 358   }
 359
 360   // Constrained Encoding (VBV)
 361   // https://slhck.info/video/2017/03/01/rate-control.html
 362   // https://trac.ffmpeg.org/wiki/Limiting%20the%20output%20bitrate
 363   const targetBitrate = getTargetBitrate(resolution, fps, VIDEO_TRANSCODING_FPS)
 364   localCommand = localCommand.outputOptions([`-maxrate ${ targetBitrate }`, `-bufsize ${ targetBitrate * 2 }`])
 365
 366   // Keyframe interval of 2 seconds for faster seeking and resolution switching.
 367   // https://streaminglearningcenter.com/blogs/whats-the-right-keyframe-interval.html
 368   // https://superuser.com/a/908325
 369   localCommand = localCommand.outputOption(`-g ${ fps * 2 }`)
 370
 371   return localCommand
 372 }