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• execSync and ffmpeg execution gap

  6 avril 2021, par Kenny Lim

  I am not sure if this is a new question but search for 5 minutes doesn't yield any result. I want to use ffmpeg to capture 10 seconds mp4 blocks into files for my other program to post-analysis. Right now, in the code below. I will see 1-1.5 seconds gap between between the generated mp4. Only one process can poke with the /dev/video0 device. I know there's overhead in executing a process, open/close device and file i/o. How can I minimize the gap ? Thanks.

  


  const { execSync, exec } = require("child_process");

capture()

function capture() {
while(true) {
  let fileName = getNewFileName();
  let captureCmd = `ffmpeg -hide_banner -loglevel error -t 10 -f v4l2 -framerate 25 -video_size 640x480 -i /dev/video0 ${fileName}.mp4 -r 1 ${fileName}-%03d.jpg`
  execSync(captureCmd)
}


  


  }

  


  function getNewFileName() {
let date = new Date()

let month = ("0" + date.getMonth()).slice(-2);
let day = ("0" + date.getDay()).slice(-2);
let hour = ("0" + date.getHours()).slice(-2);
let min = ("0" + date.getMinutes()).slice(-2);
let sec = ("0" + date.getSeconds()).slice(-2);

return "output/" + date.getFullYear() + month + day + hour + min + sec;


  


  }

  


   

  


• Selecting a library / framework for video capture & recording

  21 décembre 2011, par Saurabh Gandhi

  In one of the project that we have undertaken we are looking for a video capture & recording library. Our groundwork (based on google search) shows that vlc (libvlc), ffmpeg (libavcodec) and gstreamer are the three popular free and open source libraries / multimedia frameworks available for the same. How do these libraries compare on the following parameters :

  1. Licensing policy to allow use within a commercial product without the need to open source any of the components of the product that is using the library
  2. Ability to be used effectively in a multi-threaded environment (library should be inherently thread-safe)
  3. Easy to use and maintain
  4. Documentation : API should be well documented...this is relative... :)

  Our primary intention is to be able to capture RTSP video streams (H.264/MPEG-2/MJPEG encoded), convert these streams to raw video / frames so that it can be used for analysis / processing and later on compress these frames and store it on the disk in the form of an MP4 file (using MPEG2 / H.264 encoding).

  P.S. We understand that FFmpeg is also one of the components of vlc since vlc uses libavcodec library. Is the same true for gstreamer as well ? Does it have any ffmpeg dependency ?

  Awaiting your responses.

  Regards,

  Saurabh Gandhi

• Installing gifify on Windows

  12 octobre 2017, par Robert Wojciechowski

  So gifify is a pretty awesome script that converts videos to gifs via command line : https://github.com/vvo/gifify

  I’m keen to get this working on my Windows 10 machine. I’m pretty new to windows and relatively new to coding, but I was able to get a few things working, but ran into a problem.

  Here is what I did :

  1. Installed node.js + npm
  2. Installed FFmpeg using npm
  3. Installed ImageMagick using npm (i think i did this wrong, might have only installed the wrapper).
  4. Downloaded giflossy. It needed to be built (?)
  5. Installed Visual Studio 2015, tried to build it using nmake and got this error :

  NMAKE : fatal error U1073: don't know how to make 'win32cfg.h'

  The command I used was :

  PS C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin> .\nmake -f "C:\Users\Robert's Workstation\.npm-global\node_modules\giflossy-lossy-1.82.1\src\Makefile.w32"

  Would really appreciate some help with this :D