aboutsummaryrefslogtreecommitdiffhomepage
path: root/server/helpers/ffmpeg-utils.ts
blob: 8b9045038dba412f4dbb54187d1f7c4c9e88accd (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
import * as ffmpeg from 'fluent-ffmpeg'
import { join } from 'path'
import { getTargetBitrate, VideoResolution } from '../../shared/models/videos'
import { CONFIG, FFMPEG_NICE, VIDEO_TRANSCODING_FPS } from '../initializers'
import { processImage } from './image-utils'
import { logger } from './logger'
import { checkFFmpegEncoders } from '../initializers/checker-before-init'
import { remove } from 'fs-extra'

function computeResolutionsToTranscode (videoFileHeight: number) {
  const resolutionsEnabled: number[] = []
  const configResolutions = CONFIG.TRANSCODING.RESOLUTIONS

  // Put in the order we want to proceed jobs
  const resolutions = [
    VideoResolution.H_480P,
    VideoResolution.H_360P,
    VideoResolution.H_720P,
    VideoResolution.H_240P,
    VideoResolution.H_1080P
  ]

  for (const resolution of resolutions) {
    if (configResolutions[ resolution + 'p' ] === true && videoFileHeight > resolution) {
      resolutionsEnabled.push(resolution)
    }
  }

  return resolutionsEnabled
}

async function getVideoFileResolution (path: string) {
  const videoStream = await getVideoFileStream(path)

  return {
    videoFileResolution: Math.min(videoStream.height, videoStream.width),
    isPortraitMode: videoStream.height > videoStream.width
  }
}

async function getVideoFileFPS (path: string) {
  const videoStream = await getVideoFileStream(path)

  for (const key of [ 'r_frame_rate' , 'avg_frame_rate' ]) {
    const valuesText: string = videoStream[key]
    if (!valuesText) continue

    const [ frames, seconds ] = valuesText.split('/')
    if (!frames || !seconds) continue

    const result = parseInt(frames, 10) / parseInt(seconds, 10)
    if (result > 0) return Math.round(result)
  }

  return 0
}

async function getVideoFileBitrate (path: string) {
  return new Promise<number>((res, rej) => {
    ffmpeg.ffprobe(path, (err, metadata) => {
      if (err) return rej(err)

      return res(metadata.format.bit_rate)
    })
  })
}

function getDurationFromVideoFile (path: string) {
  return new Promise<number>((res, rej) => {
    ffmpeg.ffprobe(path, (err, metadata) => {
      if (err) return rej(err)

      return res(Math.floor(metadata.format.duration))
    })
  })
}

async function generateImageFromVideoFile (fromPath: string, folder: string, imageName: string, size: { width: number, height: number }) {
  const pendingImageName = 'pending-' + imageName

  const options = {
    filename: pendingImageName,
    count: 1,
    folder
  }

  const pendingImagePath = join(folder, pendingImageName)

  try {
    await new Promise<string>((res, rej) => {
      ffmpeg(fromPath, { niceness: FFMPEG_NICE.THUMBNAIL })
        .on('error', rej)
        .on('end', () => res(imageName))
        .thumbnail(options)
    })

    const destination = join(folder, imageName)
    await processImage({ path: pendingImagePath }, destination, size)
  } catch (err) {
    logger.error('Cannot generate image from video %s.', fromPath, { err })

    try {
      await remove(pendingImagePath)
    } catch (err) {
      logger.debug('Cannot remove pending image path after generation error.', { err })
    }
  }
}

type TranscodeOptions = {
  inputPath: string
  outputPath: string
  resolution?: VideoResolution
  isPortraitMode?: boolean
}

function transcode (options: TranscodeOptions) {
  return new Promise<void>(async (res, rej) => {
    try {
      let fps = await getVideoFileFPS(options.inputPath)
      // On small/medium resolutions, limit FPS
      if (
        options.resolution !== undefined &&
        options.resolution < VIDEO_TRANSCODING_FPS.KEEP_ORIGIN_FPS_RESOLUTION_MIN &&
        fps > VIDEO_TRANSCODING_FPS.AVERAGE
      ) {
        fps = VIDEO_TRANSCODING_FPS.AVERAGE
      }

      let command = ffmpeg(options.inputPath, { niceness: FFMPEG_NICE.TRANSCODING })
        .output(options.outputPath)
      command = await presetH264(command, options.resolution, fps)

      if (CONFIG.TRANSCODING.THREADS > 0) {
        // if we don't set any threads ffmpeg will chose automatically
        command = command.outputOption('-threads ' + CONFIG.TRANSCODING.THREADS)
      }

      if (options.resolution !== undefined) {
        // '?x720' or '720x?' for example
        const size = options.isPortraitMode === true ? `${options.resolution}x?` : `?x${options.resolution}`
        command = command.size(size)
      }

      if (fps) {
        // Hard FPS limits
        if (fps > VIDEO_TRANSCODING_FPS.MAX) fps = VIDEO_TRANSCODING_FPS.MAX
        else if (fps < VIDEO_TRANSCODING_FPS.MIN) fps = VIDEO_TRANSCODING_FPS.MIN

        command = command.withFPS(fps)
      }

      command
        .on('error', (err, stdout, stderr) => {
          logger.error('Error in transcoding job.', { stdout, stderr })
          return rej(err)
        })
        .on('end', res)
        .run()
    } catch (err) {
      return rej(err)
    }
  })
}

// ---------------------------------------------------------------------------

export {
  getVideoFileResolution,
  getDurationFromVideoFile,
  generateImageFromVideoFile,
  transcode,
  getVideoFileFPS,
  computeResolutionsToTranscode,
  audio,
  getVideoFileBitrate
}

// ---------------------------------------------------------------------------

function getVideoFileStream (path: string) {
  return new Promise<any>((res, rej) => {
    ffmpeg.ffprobe(path, (err, metadata) => {
      if (err) return rej(err)

      const videoStream = metadata.streams.find(s => s.codec_type === 'video')
      if (!videoStream) throw new Error('Cannot find video stream of ' + path)

      return res(videoStream)
    })
  })
}

/**
 * A slightly customised version of the 'veryfast' x264 preset
 *
 * The veryfast preset is right in the sweet spot of performance
 * and quality. Superfast and ultrafast will give you better
 * performance, but then quality is noticeably worse.
 */
async function presetH264VeryFast (command: ffmpeg.FfmpegCommand, resolution: VideoResolution, fps: number): Promise<ffmpeg.FfmpegCommand> {
  let localCommand = await presetH264(command, resolution, fps)
  localCommand = localCommand.outputOption('-preset:v veryfast')
             .outputOption([ '--aq-mode=2', '--aq-strength=1.3' ])
  /*
  MAIN reference: https://slhck.info/video/2017/03/01/rate-control.html
  Our target situation is closer to a livestream than a stream,
  since we want to reduce as much a possible the encoding burden,
  altough not to the point of a livestream where there is a hard
  constraint on the frames per second to be encoded.

  why '--aq-mode=2 --aq-strength=1.3' instead of '-profile:v main'?
    Make up for most of the loss of grain and macroblocking
    with less computing power.
  */

  return localCommand
}

/**
 * A preset optimised for a stillimage audio video
 */
async function presetStillImageWithAudio (
  command: ffmpeg.FfmpegCommand,
  resolution: VideoResolution,
  fps: number
): Promise<ffmpeg.FfmpegCommand> {
  let localCommand = await presetH264VeryFast(command, resolution, fps)
  localCommand = localCommand.outputOption('-tune stillimage')

  return localCommand
}

/**
 * A toolbox to play with audio
 */
namespace audio {
  export const get = (option: ffmpeg.FfmpegCommand | string) => {
    // without position, ffprobe considers the last input only
    // we make it consider the first input only
    // if you pass a file path to pos, then ffprobe acts on that file directly
    return new Promise<{ absolutePath: string, audioStream?: any }>((res, rej) => {

      function parseFfprobe (err: any, data: ffmpeg.FfprobeData) {
        if (err) return rej(err)

        if ('streams' in data) {
          const audioStream = data.streams.find(stream => stream['codec_type'] === 'audio')
          if (audioStream) {
            return res({
              absolutePath: data.format.filename,
              audioStream
            })
          }
        }

        return res({ absolutePath: data.format.filename })
      }

      if (typeof option === 'string') {
        return ffmpeg.ffprobe(option, parseFfprobe)
      }

      return option.ffprobe(parseFfprobe)
    })
  }

  export namespace bitrate {
    const baseKbitrate = 384

    const toBits = (kbits: number): number => { return kbits * 8000 }

    export const aac = (bitrate: number): number => {
      switch (true) {
      case bitrate > toBits(baseKbitrate):
        return baseKbitrate
      default:
        return -1 // we interpret it as a signal to copy the audio stream as is
      }
    }

    export const mp3 = (bitrate: number): number => {
      /*
      a 192kbit/sec mp3 doesn't hold as much information as a 192kbit/sec aac.
      That's why, when using aac, we can go to lower kbit/sec. The equivalences
      made here are not made to be accurate, especially with good mp3 encoders.
      */
      switch (true) {
      case bitrate <= toBits(192):
        return 128
      case bitrate <= toBits(384):
        return 256
      default:
        return baseKbitrate
      }
    }
  }
}

/**
 * Standard profile, with variable bitrate audio and faststart.
 *
 * As for the audio, quality '5' is the highest and ensures 96-112kbps/channel
 * See https://trac.ffmpeg.org/wiki/Encode/AAC#fdk_vbr
 */
async function presetH264 (command: ffmpeg.FfmpegCommand, resolution: VideoResolution, fps: number): Promise<ffmpeg.FfmpegCommand> {
  let localCommand = command
    .format('mp4')
    .videoCodec('libx264')
    .outputOption('-level 3.1') // 3.1 is the minimal ressource allocation for our highest supported resolution
    .outputOption('-b_strategy 1') // NOTE: b-strategy 1 - heuristic algorythm, 16 is optimal B-frames for it
    .outputOption('-bf 16') // NOTE: Why 16: https://github.com/Chocobozzz/PeerTube/pull/774. b-strategy 2 -> B-frames<16
    .outputOption('-pix_fmt yuv420p') // allows import of source material with incompatible pixel formats (e.g. MJPEG video)
    .outputOption('-map_metadata -1') // strip all metadata
    .outputOption('-movflags faststart')

  const parsedAudio = await audio.get(localCommand)

  if (!parsedAudio.audioStream) {
    localCommand = localCommand.noAudio()
  } else if ((await checkFFmpegEncoders()).get('libfdk_aac')) { // we favor VBR, if a good AAC encoder is available
    localCommand = localCommand
      .audioCodec('libfdk_aac')
      .audioQuality(5)
  } else {
    // we try to reduce the ceiling bitrate by making rough correspondances of bitrates
    // of course this is far from perfect, but it might save some space in the end
    const audioCodecName = parsedAudio.audioStream[ 'codec_name' ]
    let bitrate: number
    if (audio.bitrate[ audioCodecName ]) {
      bitrate = audio.bitrate[ audioCodecName ](parsedAudio.audioStream[ 'bit_rate' ])

      if (bitrate === -1) localCommand = localCommand.audioCodec('copy')
      else if (bitrate !== undefined) localCommand = localCommand.audioBitrate(bitrate)
    }
  }

  // Constrained Encoding (VBV)
  // https://slhck.info/video/2017/03/01/rate-control.html
  // https://trac.ffmpeg.org/wiki/Limiting%20the%20output%20bitrate
  const targetBitrate = getTargetBitrate(resolution, fps, VIDEO_TRANSCODING_FPS)
  localCommand = localCommand.outputOptions([`-maxrate ${ targetBitrate }`, `-bufsize ${ targetBitrate * 2 }`])

  // Keyframe interval of 2 seconds for faster seeking and resolution switching.
  // https://streaminglearningcenter.com/blogs/whats-the-right-keyframe-interval.html
  // https://superuser.com/a/908325
  localCommand = localCommand.outputOption(`-g ${ fps * 2 }`)

  return localCommand
}