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import { logger } from '@server/helpers/logger'
import { getTargetBitrate, VideoResolution } from '../../shared/models/videos'
import { AvailableEncoders, buildStreamSuffix, EncoderOptionsBuilder } from '../helpers/ffmpeg-utils'
import {
canDoQuickAudioTranscode,
ffprobePromise,
getAudioStream,
getMaxAudioBitrate,
getVideoFileBitrate,
getVideoStreamFromFile
} from '../helpers/ffprobe-utils'
import { VIDEO_TRANSCODING_FPS } from '../initializers/constants'
/**
*
* Available encoders and profiles for the transcoding jobs
* These functions are used by ffmpeg-utils that will get the encoders and options depending on the chosen profile
*
*/
// Resources:
// * https://slhck.info/video/2017/03/01/rate-control.html
// * https://trac.ffmpeg.org/wiki/Limiting%20the%20output%20bitrate
const defaultX264VODOptionsBuilder: EncoderOptionsBuilder = async ({ input, resolution, fps }) => {
const targetBitrate = await buildTargetBitrate({ input, resolution, fps })
if (!targetBitrate) return { outputOptions: [ ] }
return {
outputOptions: [
`-r ${fps}`,
`-maxrate ${targetBitrate}`,
`-bufsize ${targetBitrate * 2}`
]
}
}
const defaultX264LiveOptionsBuilder: EncoderOptionsBuilder = async ({ resolution, fps, streamNum }) => {
const targetBitrate = getTargetBitrate(resolution, fps, VIDEO_TRANSCODING_FPS)
return {
outputOptions: [
`${buildStreamSuffix('-r:v', streamNum)} ${fps}`,
`${buildStreamSuffix('-b:v', streamNum)} ${targetBitrate}`,
`-maxrate ${targetBitrate}`,
`-bufsize ${targetBitrate * 2}`
]
}
}
const defaultAACOptionsBuilder: EncoderOptionsBuilder = async ({ input, streamNum }) => {
const probe = await ffprobePromise(input)
if (await canDoQuickAudioTranscode(input, probe)) {
logger.debug('Copy audio stream %s by AAC encoder.', input)
return { copy: true, outputOptions: [] }
}
const parsedAudio = await getAudioStream(input, probe)
// We try to reduce the ceiling bitrate by making rough matches of bitrates
// Of course this is far from perfect, but it might save some space in the end
const audioCodecName = parsedAudio.audioStream['codec_name']
const bitrate = getMaxAudioBitrate(audioCodecName, parsedAudio.bitrate)
logger.debug('Calculating audio bitrate of %s by AAC encoder.', input, { bitrate: parsedAudio.bitrate, audioCodecName })
if (bitrate !== undefined && bitrate !== -1) {
return { outputOptions: [ buildStreamSuffix('-b:a', streamNum), bitrate + 'k' ] }
}
return { outputOptions: [ ] }
}
const defaultLibFDKAACVODOptionsBuilder: EncoderOptionsBuilder = ({ streamNum }) => {
return { outputOptions: [ buildStreamSuffix('-q:a', streamNum), '5' ] }
}
// Used to get and update available encoders
class VideoTranscodingProfilesManager {
private static instance: VideoTranscodingProfilesManager
// 1 === less priority
private readonly encodersPriorities = {
video: [
{ name: 'libx264', priority: 100 }
],
// Try the first one, if not available try the second one etc
audio: [
// we favor VBR, if a good AAC encoder is available
{ name: 'libfdk_aac', priority: 200 },
{ name: 'aac', priority: 100 }
]
}
private readonly availableEncoders = {
vod: {
libx264: {
default: defaultX264VODOptionsBuilder
},
aac: {
default: defaultAACOptionsBuilder
},
libfdk_aac: {
default: defaultLibFDKAACVODOptionsBuilder
}
},
live: {
libx264: {
default: defaultX264LiveOptionsBuilder
},
aac: {
default: defaultAACOptionsBuilder
}
}
}
private constructor () {
}
getAvailableEncoders (): AvailableEncoders {
const encodersToTry = {
video: this.getEncodersByPriority('video'),
audio: this.getEncodersByPriority('audio')
}
return Object.assign({}, this.availableEncoders, { encodersToTry })
}
getAvailableProfiles (type: 'vod' | 'live') {
return this.availableEncoders[type]
}
private getEncodersByPriority (type: 'video' | 'audio') {
return this.encodersPriorities[type]
.sort((e1, e2) => {
if (e1.priority > e2.priority) return -1
else if (e1.priority === e2.priority) return 0
return 1
})
.map(e => e.name)
}
static get Instance () {
return this.instance || (this.instance = new this())
}
}
// ---------------------------------------------------------------------------
export {
VideoTranscodingProfilesManager
}
// ---------------------------------------------------------------------------
async function buildTargetBitrate (options: {
input: string
resolution: VideoResolution
fps: number
}) {
const { input, resolution, fps } = options
const probe = await ffprobePromise(input)
const videoStream = await getVideoStreamFromFile(input, probe)
if (!videoStream) return undefined
const targetBitrate = getTargetBitrate(resolution, fps, VIDEO_TRANSCODING_FPS)
// Don't transcode to an higher bitrate than the original file
const fileBitrate = await getVideoFileBitrate(input, probe)
return Math.min(targetBitrate, fileBitrate)
}
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