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• About the delay of Electron playing FFpmeg transcoded video

  26 juillet 2020, par Yohann

  In the Electron project, you need to try to play the video screen of the camera

  


  The camera is Haikang’s webcam

  


  Get real-time video stream through RTSP protocol

  


  rtsp://admin:admin@192.168.0.253/main/Channels/

  


  There will be a delay of about 3s when playing through the VLC player

  


  Then when used in the project, create a websocket service in Electron through the main process, decode the rtsp video through fluent-ffmpeg, and convert it to flv stream and push it to the rendering process

  


  import * as express from 'express'
import * as expressWebSocket from 'express-ws'
import ffmpeg from 'fluent-ffmpeg'
import webSocketStream from 'websocket-stream/stream'
const path = require('path')

let ffmpegPath
if (process.env.NODE_ENV === 'development') {
  ffmpegPath = path.join(__static, 'ffmpeg', 'bin', 'ffmpeg.exe')
} else {
  ffmpegPath = path.join(process.cwd(), 'ffmpeg', 'bin', 'ffmpeg.exe')
}
ffmpeg.setFfmpegPath(ffmpegPath)

// Start video transcoding service
function videoServer () {
  let app = express()
  app.use(express.static(__dirname))
  expressWebSocket(app, null, {
    perMessageDeflate: true
  })
  app.ws('/rtsp/', rtspRequestHandle)
  app.listen(8888)
  console.log('Create a monitoring service')
}

//RTSP transcoding method
function rtspRequestHandle (ws, req) {
  console.log('rtsp request handle')
  const stream = webSocketStream(ws, {
    binary: true,
    browserBufferTimeout: 1000000
  },
  {
    browserBufferTimeout: 1000000
  })
  let url = req.query.url
  console.log('rtsp url:', url)
  try {
    ffmpeg(url)
      .addInputOption('-rtsp_transport', 'tcp', '-buffer_size', '102400') // Here you can add some RTSP optimized parameters
      .outputOptions([
        '-fflags',
        'nobuffer',
        '-tune',
        'zerolatency'
      ])
      .on('start', function () {
        console.log(url, 'Stream started.')
      })
      .on('codecData', function () {
        console.log(url, 'Stream codecData.')
      })
      .on('error', function (err) {
        console.log(url, 'An error occured: ', err.message)
      })
      .on('end', function () {
        console.log(url, 'Stream end!')
      })
      .outputFormat('flv').videoCodec('copy').noAudio().pipe(stream)
  } catch (error) {
    console.log(error)
  }
}

export default videoServer


  


  The rendering process parses the video stream and plays the video through flv.js

  


  <template>&#xA;  <div class="video">&#xA;    <video class="video-box" ref="player"></video>&#xA;  </div>&#xA;</template>&#xA;&#xA;<code class="echappe-js">&lt;script&gt;&amp;#xA;  import flvjs from &amp;#x27;flv.js&amp;#x27;&amp;#xA;  export default {&amp;#xA;    name: &amp;#x27;videopage&amp;#x27;,&amp;#xA;    props: {&amp;#xA;      rtsp: String&amp;#xA;    },&amp;#xA;    data () {&amp;#xA;      return {&amp;#xA;        player: null&amp;#xA;      }&amp;#xA;    },&amp;#xA;    mounted () {&amp;#xA;      console.log(flvjs.isSupported())&amp;#xA;      if (flvjs.isSupported()) {&amp;#xA;        let video = this.$refs.player&amp;#xA;        console.log(video)&amp;#xA;        if (video) {&amp;#xA;          this.player = flvjs.createPlayer({&amp;#xA;            type: &amp;#x27;flv&amp;#x27;,&amp;#xA;            isLive: true,&amp;#xA;            url: &amp;#x27;ws://localhost:8888/rtsp/?url=&amp;#x27; &amp;#x2B; this.rtsp&amp;#xA;          }, {&amp;#xA;            enableStashBuffer: true&amp;#xA;          })&amp;#xA;          console.log(this.player)&amp;#xA;          this.player.attachMediaElement(video)&amp;#xA;          try {&amp;#xA;            this.player.load()&amp;#xA;            this.player.play()&amp;#xA;          } catch (error) {&amp;#xA;            console.log(error)&amp;#xA;          }&amp;#xA;        }&amp;#xA;      }&amp;#xA;    },&amp;#xA;    methods: {&amp;#xA;      getCurrentFrame () {&amp;#xA;        let video = this.$refs.player&amp;#xA;        let scale = 1&amp;#xA;        let canvas = document.createElement(&amp;#x27;canvas&amp;#x27;)&amp;#xA;        canvas.width = video.videoWidth * scale&amp;#xA;        canvas.height = video.videoHeight * scale&amp;#xA;        canvas.getContext(&amp;#x27;2d&amp;#x27;).drawImage(video, 0, 0, canvas.width, canvas.height)&amp;#xA;        return canvas.toDataURL(&amp;#x27;image/png&amp;#x27;)&amp;#xA;      }&amp;#xA;    },&amp;#xA;    beforeDestroy () {&amp;#xA;      this.player &amp;amp;&amp;amp; this.player.destory &amp;amp;&amp;amp; this.player.destory()&amp;#xA;    }&amp;#xA;  }&amp;#xA;&lt;/script&gt;&#xA;&#xA;&#xA;

  


  Then there will be a delay of about 3s when playing, and the delay will increase with the playing time

  


  There will be a delay of 10 minutes in the later period

  


  Is there any way to control this delay time

  


  Or is there any other decoding scheme that can be used ?

  


  Solutions that can support electron

  


• avcodec/cfhd : use LUT for 9 and 18 codebook decompanding

  3 août 2020, par Paul B Mahol

  avcodec/cfhd : use LUT for 9 and 18 codebook decompanding
  Also fix codebook 9 decompanding, fixing artifact with codebook 9
  
  samples. Reused Gagandeep Singh patch.
  

  • [DH] libavcodec/cfhd.c
  • [DH] libavcodec/cfhd.h

• Build OpenCv using static ffmpeg library

  24 juillet 2020, par gaurav agarwal

  I am trying to build opencv for one of the commercial product. That commercial product already contains a static build of ffmpeg executable. While building OpenCv I am seeing bunch of failure most probably due to linking issues with ffmpeg.

  


  Is it possible to build OpenCv using static ffmpeg library ? In OpenCv installation doc I can see mentioned prerequisite is :

  


  


  ffmpeg or libav development packages : libavcodec-dev, libavformat-dev,
libswscale-dev

  


  


  I guess this means OpenCv needs these lib to be present as shared libs. Any expert opinion will be helpful !!!