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• Overlaying video with ffmpeg

  11 novembre 2012, par elee

  I'm attempting to write a script that will merge 2 separate video files into 1 wider one, in which both videos play back simultaneously. I have it mostly figured out, but when I view the final output, the video that I'm overlaying is extremely slow.

  Here's what I'm doing :

  1. Expand the left video to the final video dimensions

     ffmpeg -i left.avi -vf "pad=640:240:0:0:black" left_wide.avi

  2. Overlay the right video on top of the left one

     ffmpeg -i left_wide.avi -vf "movie=right.avi [mv] ; [in][mv] overlay=320:0" combined_video.avi

  In the resulting video, the playback on the right video is about half the speed of the left video. Any idea how I can get these files to sync up ?

• Nodejs spawn - child processes

  24 février 2019, par z Eyeland

  My nodejs application is running on raspberry Pi. The program uses spawn child process to trigger bash scripts which record or compress the previous recorded file. The program records fine. After recording the user selects the compress button. This kills the recording spawn process and fires the bash script for compression. The issue I am having is that whenever the video length gets around 1min long the compression spawn process times out or something. I ran ps -ef to view all process and i noticed that the compression script is still there. She the video length is short - the compression spawn process completes its cycle and send api request to shutdown the process. Here is some code

  Api with console log that lets me know when compression is done. When the video clips are longer around 1min this GET request never logs’=

  app.get('/clovis/api/led', function (req, res){
  
  console.log("api activated for resetLED function");
  
  resetLED();
  
  console.log("reset was completed");
  
  })

  Nodejs spawns that call different bash scripts

  function setBashScript(scriptNum){
  
  if(scriptNum == 0){
  
      //do this
  
       child = spawn('./feedmpeg.sh');
  
   resetLED();
  
  }
  
  if(scriptNum == 1){
  
      //do this
  
      updatePicturePath();
  
       child = spawn('./feedSnapshot.sh',[pictureFilePath]);
  
  resetLED();
  
  }
  
  if(scriptNum == 2){
  
      //do this
  
      updateVideoPath();
  
      child = spawn('./feedmpegRecord.sh',[videoFilePath]);
  
      isRecording = true;
  
  resetLED();
  
  ledRed();
  
  }
  
  if(scriptNum == 10){
  
      //do this
  
      updateCompressedPath();
  
       child = spawn('./generalCompressionMP4.sh',[videoFilePath,compressedFilePath]);
  
       isRecording = false;
  
   resetLED();
  
   ledBlue();
  
    }
  
    }

  generalCompressionMP4.sh - The spawn process that doesnt complete if video length is too long. Generally when the process is complete, I head over to the localhost server and view the mp4 file. When this issue occures the mp4 doesnt load, the old path is not removed, and the api doesnt send.

  #!/bin/bash
  
  FILEPATH="$1"
  
  COMPRESSIONPATH="$2"
  
  ffmpeg -i $FILEPATH -vcodec h264 -acodec mp2 $COMPRESSIONPATH
  
  sudo rm $FILEPATH
  
  curl -H "Content-Type: application/json" -X POST 
  
  http://localhost:3000/clovis/api/led

  Why might the process get stuck ? How can i fix this ? Should I not use spawn child process ?

• Is there something equivalent to FilterKit for android ?

  29 octobre 2014, par Varun Jain

  I am looking to put filters on a video after it has been recorded. Explored FFMPEG but it is way too slow (take 10-15 seconds for a 20 second video). The instagram app does it in under 1-2 seconds every time. Sample FFMPEG code I am using :

  ffmpeg -y -i vid_0.mp4 -preset ultrafast  -vf format=gray,format=yuv422p -vsync 2  webcam.mp4

  Is there a library similar to FilterKit for android ? Is there a feasible way in which I can use FilterKit on Android ? Any other approach to apply filters on video would also be welcome.

  Note : I am not talking about giving the user a preview, that is easily done by using a surface view. I need to convert the video.