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• How to read frames of a video and write them on another video output using FFMPEG and nodejs

  29 décembre 2023, par Aviato

  I am working on a project where I need to process video frames one at a time in Node.js. I aim to avoid storing all frames in memory or the filesystem due to resource constraints. I plan to use the ffmpeg from child processes for video processing.
I tried reading a video file and then output frames of it in the filesystem first for testing purposes :-

  


  const ffmpegProcess = spawn('ffmpeg', [
  '-i', videoFile,
  'testfolder/%04d.png' // Output frames to stdout
]);


  


  and the above code works fine, it saves the video frames as png files in the filesystem. Now instead of saving them in the file system, I want to read the frames on at a time and use a image manipulation library and than write the final edited frames to another video as output

  


  I tried this :-

  


  const ffmpegProcess = spawn('ffmpeg', [
  '-i', videoFile,
  'pipe:1' // Output frames to stdout
]);

const ffmpegOutputProcess = spawn('ffmpeg', [
  '-i', '-',
  'outputFileName.mp4'
  ]);

ffmpegProcess.stdout.on('data', (data) => {
  // Process the frame data as needed
  console.log('Received frame data:');
  ffmpegOutputProcess.stdin.write(data)
});

ffmpegProcess.on('close', (code) => {
  if (code !== 0) {
    console.error(`ffmpeg process exited with code ${code}`);
  } else {
    console.log('ffmpeg process successfully completed');
    
  }
});

// Handle errors
ffmpegProcess.on('error', (err) => {
  console.error('Error while spawning ffmpeg:', err);
});


  


  But when I tried above code and also some other modifications in the input and output suffix in the command I got problems as below :-

  


  

  1. ffmpeg process exited with code 1

  


  2. The final output video was corrupted when trying to initializing the filters for commands :-

  


  


  
const ffmpegProcess = spawn('ffmpeg', [
 '-i', videoFile,
 '-f', 'rawvideo',
 '-pix_fmt', 'rgb24',
 'pipe:1' // Output frames to stdout
]);

const ffmpegOutputCommand = [
 '-f', 'rawvideo',
 '-pix_fmt', 'rgb24',
 '-s', '1920x1080',
 '-r', '30',
 '-i', '-',
 '-c:v', 'libx264',
 '-pix_fmt', 'yuv420p',
 outputFileName
];


  


  Thank you so much in advance :)

  


• Create drawbox with ffmpeg between specific seconds (without reencoding whole video - faster)

  31 mars 2022, par protter

  My plan was to put a transparent red box behind a video. This box should only be present from second 1-45.
But if the videos are 3 hours long, the process takes a long time although it only has to process 45 seconds.

  


  My first attempt takes too long :

  


  ffmpeg -i %1 -vf drawbox=0:9*ih/10:iw:ih/10:t=fill:color=red@0.5:enable='between(t,1,45)' "%~dp0transpred\%~n1%~x1

  


  Then i tried splitting the video into two parts. put the box on the first video, and then put the two back together again.

  


  ffmpeg  -ss 00:00:00.0000 -i %1 -to 00:00:45.0000  -vf drawbox=0:9*ih/10:iw:ih/10:t=fill:color=red@0.5:enable='between(t,1,45)' "%~dp0transpred\%~n1A%~x1"

  


  FFMpeg -ss 00:00:45.0000 -i %1 -c:v copy -c:a copy -avoid_negative_ts make_zero "%~dp0transpred\%~n1B%~x1"

  


  But i don't even have to try to put these two together, because they are not separated exactly at the second. I have read that this is due to "timestamps" and the different video and audio streams.

  


  Now I'm trying an approach to create a stream with the bar, and then overlay it with the finished video. I haven't quite managed that yet, and I don't know if it's faster.
Shortening the video is very fast.

  


  EDIT (Added as a replacement for the comment later)

  


  Thanks for your help I have almost done it with a slightly different approach. Unfortunately, the second part now always has no sound. No matter if I put A and B (B no sound) or B and A (A no sound) together.

  


  

  1. First split with mkvmerge so i have no worrys about the keyframes and get the exact time
mkvmerge --split timestamps:00:00:45.100 A.MKV -o splitmkm.mkv

  


  2. Then add the Bar (Black because of easier testing) :
ffmpeg -i splitmkm-001.mkv -vf drawbox=0:9*ih/10:iw:ih/10:t=fill BAR1.MKV

  


  3. Merge (mkvmerge ends with error) :
ffmpeg -safe 0 -f concat -i list.txt -c copy output1.mkv

  


  


  EDIT (Answer to kesh)

  


  This was the error Again, audio codec config's must match across all your concat files. The drawbox changed the audio Codec from AC-3 to Vorbis.

  


  the procedure is now :

  


  

  1. mkvtoolnix\mkvmerge --split timestamps:00:00:05.100  %1 -o A_splitmkm.mkv with mkvmerge i have an exact split at the time, and i don't have to learn about keyframes.

  


  2. ffmpeg -i A_splitmkm-001.mkv -vf drawbox=0:9*ih/10:iw:ih/10:t=fill:color=red A_BARmkm.MKV create the Bar

  


  3. ffmpeg -i A_BARmkm.MKV -i A_splitmkm-001.mkv -map 0:v  -map 1 -map -1:v  -c copy A_BARwithAudio.mkv redo the step with the changed audio from drawbox

  


  4. ffmpeg -safe 0 -f concat -i list.txt -map 0  -c copy A_output1.mkv merge

  


  


  Now everything works.
Thanks alot !

  


• imageJpeg and FFMPEG in windows vs linux

  25 janvier 2020, par Tanmay Gawankar

  I have a working code for converting image to a 5 seconds video using FFMPEG.

  The problem is, The code only works for downloaded images, FFMPEG doesn’t convert image to video when image is generated programmatically ONLY IN LINUX.

  PHP code

  <?php
  
      $downloadedF="folder/d.jpg";
  
      $downloadedV="folder/d.mp4";
  
      $renderedF="folder/r.jpg";
  
      $renderedV="folder/r.mp4";
  
  
  
      $op_d=shell_exec("ffmpeg -r 1/5 -i ".$downloadedF." -c:v libx264 -vf fps=25 -pix_fmt yuv420p ".$downloadedV);
  
      $op_r=shell_exec("ffmpeg -r 1/5 -i ".$renderedF." -c:v libx264 -vf fps=25 -pix_fmt yuv420p ".$renderedV);
  
  
  
      echo "Errors:<br />".$op_d."<br /><br />".$op_r;
  
  ?>

  The d.mp4(or output for downloaded image) is getting generated for both Windows and Linux
  The r.mp4(or output for rendered image) gets generated only in Windows and 48 bytes empty file is getting created in Linux

  System :

  XAMPP on Windows 10(Development)
  Godaddy Starter plan hosting - Linux(Probably redhat)(Production)

  File Structure

  root folder
  
      |-index.php
  
      |-ffmpeg (will be ffmpeg.exe in Windows)
  
      |-folder
  
          |-d.jpg (random downloaded image from google)
  
          |-d.mp4 (Will be created - video converted from downloaded image)
  
          |-r.jpg (rendered image using php imagejpg)
  
          |-r.mp4 (Will be created - video converted from rendered image)

  Rendered Image Code :

  $imgFF = imagecreatetruecolor($videoWidth, $videoHeight);
  
  //---adding many text using imagettftext();
  
  imagejpeg($imgFF, $path."-000.jpg");  //for this example, I copied output to folder as r.jpg

  Edit 1 :

  The return value of shell_exec has no error/output even after adding

  error_reporting(E_ALL);
  
  ini_set('display_errors', 1);

  Edit 2 :

  The log for successful conversion can be found at Here
  The log for unsuccessful conversion of rendered image can be found at Here

  Note :

  • The scenario here is minimized and code is separated from long code.
  • In Linux command i add ./ for FFMPEG