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• Capture Windows screen with ffmpeg

  4 mars 2021, par kamae

  The ffmpeg is cross-platform and very powerful software to handle video/audio or to stream it.
On Linux ffmpeg can capture X11 screen with a command below :

  



  ffmpeg -f x11grab -r 25 -s cif -i :0.0 out.mpeg


  



  But is it possible to grab Windows Desktop with ffmpeg ?

  


• FFMPEG for aws s3 bucket signed url not working in node js

  21 août 2018, par ahmed sharief

  I am trying to create thumbnails from an amazon s3 bucket signed url. I am able to generate thumbnails when i run the command in terminal

  ffmpeg -ss 00:00:02 -i "https://test-s3-bucket.s3.ap-south-1.amazonaws.com/user_gallery_assets/5b6936069ac2bf0602085367/gallery/images/5b7be08527641dee8c1f8134.mp4?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=xxxxxxxxx%2F20180821%2Fap-south-1%2Fs3%2Faws4_request&X-Amz-Date=20180821T095101Z&X-Amz-Expires=900&X-Amz-Signature=d7f81f4eed3d6c87c04dc1b0ad06beeb946afa33d417585f57fad72aeadb3ac0&X-Amz-SignedHeaders=host" -vframes 1 -q:v 2 -f image2 output.jpg

  I am running the above command in terminal and its working fine but when i try to implement the same in node js its showing "no such file or directory error". Though i am encoding the url with double quotes then also its showign same error. Here is my node js code....

  function uploadThumbNailForVideo(obj,url, thumb_url){
  
      return new Promise((resolve, reject) => resolve(url))
  
      .then((url) => awsHelper.getImage(url))
  
      .then((result) => { 
  
  
  
          var resUrl = "\""+result+"\"";
  
  
  
          var args = [ 
  
              '-i', resUrl, 
  
              '-ss', '00:00:02', 
  
              '-vframes', '1', 
  
              '-f','image2', 
  
              'output.jpg'
  
          ]
  
          //console.log(args)
  
          var ffmpeg = require('child_process').spawn('ffmpeg', args);
  
  
  
          ffmpeg.on('error', function (err) {
  
              console.log(err);
  
          });
  
  
  
          ffmpeg.on('close', function (code) {
  
  
  
          });
  
  
  
          ffmpeg.stderr.on('data', function (data) {
  
              var tData = data.toString('utf8');
  
              var a = tData.split('\n');
  
              console.log("A",a); 
  
          });
  
  
  
          ffmpeg.stdout.on('data', function (data) {
  
              //
  
          });
  
  
  
  
  
      });

  }

  and i am getting the following error

  A [ 'ffmpeg version 4.0.2 Copyright (c) 2000-2018 the FFmpeg 
  
  developers' ]
  
  A [ '',
  
    '  built with Apple LLVM version 9.1.0 (clang-902.0.39.2)',
  
    '  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.0.2 --enable- 
  
  shared --enable-pthreads --enable-version3 --enable-hardcoded-tables -- 
  
  enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable- 
  
  gpl --enable-libmp3lame --enable-libx264 --enable-libxvid --enable- 
  
  opencl --enable-videotoolbox --disable-lzma',
  
     '  libavutil      56. 14.100 / 56. 14.100',
  
     '  libavcodec     58. 18.100 / 58. 18.100',
  
    '  libavformat    58. 12.100 / 58. 12.100',
  
    '  libavdevice    58.  3.100 / 58.  3.100',
  
    '  libavfilter     7. 16.100 /  7. 16.100',
  
    '  libavresample   4.  0.  0 /  4.  0.  0',
  
    '  libswscale      5.  1.100 /  5.  1.100',
  
    '  libswresample   3.  1.100 /  3.  1.100',
  
    '  libpostproc    55.  1.100 / 55.  1.100',
  
    '"https://test-s3-bucket.s3.ap-south-1.amazonaws.com/user_gallery_assets/5b6936069ac2bf0602085367/gallery/images/5b7be08527641dee8c1f8134.mp4?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=xxxxxxxxx%2F20180821%2Fap-south-1%2Fs3%2Faws4_request&X-Amz-Date=20180821T095101Z&X-Amz-Expires=900&X-Amz-Signature=d7f81f4eed3d6c87c04dc1b0ad06beeb946afa33d417585f57fad72aeadb3ac0&X-Amz-SignedHeaders=host": No such file or directory',
  
    '' ]
  
  
  
  ffmpeg exited with code 1

• How to generate video as fast as possible with subtitles and audio on node.js + ffmpeg ?

  12 septembre 2018, par DSeregin

  Intro :

  We receive from the site some pieces of text
  Pieces arrive to node.js-server

  At the output we need to get a video, merged from all the pieces of text, voiced by the machine voice, with the added subtitles and audio substrate. So that user could be share this video in the social networks. MKV format doesn`t supported by VK.com

  The options that we have tried :
  1. Get all the text at once, generate the entire speech, create a file with subtitles, burn subtitles in the video .mp4 (vk.com does not support the .mkv container). It took 12 seconds of operations for a 45-second video on the local computer.
  2. Generate audio and video files for each piece of text (with added subtitles). It took one second for one piece of text. At the final request, we merge all pieces together. The last request (merging) took 2-3 seconds, which is already bearable.

  The second variant looks acceptable in terms of speed, but if you run 50 clients at the same time, then the computer (tested on a MacBook PRO 2013, 2.4 GHz i7, 8gb 1600 Mhz DDR3, SSD 256gb) processed only 1 piece from 1 client in 60 seconds (60 times slower), then the computer hung tight.

  • Generation of audio is done through Amazon Polly
  • Generate subtitles via https://github.com/gsantiago/subtitle.js#readme
  • From node.js we call ffmpeg using https://github.com/fluent-ffmpeg/node-fluent-ffmpeg
  • Resolution for video - 1280x720

  The commands we used :

  • Burn video subtitles and trim up to conditional 6 seconds (in the code send unix timestamp)

  ffmpeg -i import / back.mov -i export_0 / tmp.srt -scodec mov_text -t 6 export_0 / output.mov

  • Merging all audio

  ffmpeg -i audio1.mp3 .... -i audio15.mp3 merged.mp3

  • Overlay audio-substrate on the text

  ffmpeg -i merged.mp3 -i back.mp3 -filter_complex amerge -ac 2-c: a libmp3lame -q: a 4 -shortest audio.mp3

  • Merging all videos

  ffmpeg -i video.txt -f concat -c copy video.mp4

  • Overlay audio on video

  ffmpeg -i audio.mp3 -i video.mp4 -i test.mp4 -i export / output.mp3 -c: v copy -c: a aac -map 0: v: 0 -map 1: a: 0 -shortest output .mp4

  Questions that torment :

  1. Is it faster ?

  2. Can I use other codecs or methods of gluing without re-encoding ?

  3. Try to call ffmpeg directly without a wrapper ? (in fact, it gives 50-100 ms of speed)

  4. Try not to save to disk, and write data to Stream and have them glue together in the end ?