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• How to maximize ffmpeg crop and overlay thousand block in same time ?

  22 juin 2022, par yuno saga

  I try to encrypt a frame of video to random of 16x16 block. so the result will be like artifact video. but exactly it can be decode back. only the creation that know the decode algorithm. but my problem is ffmpeg encode so slow. 3 minutes video, 854x480 (480p) https://www.youtube.com/watch?v=dyRsYk0LyA8. this example result frame that have been filter https://i.ibb.co/0nvLzkK/output-9.jpg. each frame have 1589 block. how to speed up this things ? 3 minutes only 24 frame done. the vido have 5000 thousand frame, so for 3 minutes video it takes 10 hours. i dont know why ffmpeg only take my cpu usage 25%.

  


  const { spawn } = require('child_process');
const fs = require('fs');

function shuffle(array) {
    let currentIndex = array.length,  randomIndex;
  
    // While there remain elements to shuffle.
    while (currentIndex != 0) {
  
      // Pick a remaining element.
      randomIndex = Math.floor(Math.random() * currentIndex);
      currentIndex--;
  
      // And swap it with the current element.
      [array[currentIndex], array[randomIndex]] = [
        array[randomIndex], array[currentIndex]];
    }
  
    return array;
  }

function filter(width, height) {
    const sizeBlock = 16;
    let filterCommands = '';
    let totalBlock = 0;
    const widthLengthBlock = Math.floor(width / sizeBlock);
    const heightLengthBlock = Math.floor(height / sizeBlock);
    let info = [];

    for (let i=0; i < widthLengthBlock; i++) {
        for (let j=0; j < heightLengthBlock; j++) {
            const xPos = i*sizeBlock;
            const yPos = j*sizeBlock;
            filterCommands += `[0]crop=${sizeBlock}:${sizeBlock}:${(xPos)}:${(yPos)}[c${totalBlock}];`;

            info.push({
                id: totalBlock,
                x: xPos,
                y: yPos
            });

            totalBlock += 1;
        }   
    }

    info = shuffle(info);

    for (let i=0; i < info.length; i++) {
        if (i == 0) filterCommands += '[0]';
        if (i != 0) filterCommands += `[o${i}]`;

        filterCommands += `[c${i}]overlay=x=${info[i].x}:y=${info[i].y}`;

        if (i != (info.length - 1)) filterCommands += `[o${i+1}];`;     
    }

    return filterCommands;
}

const query = filter(854, 480);

fs.writeFileSync('filter.txt', query);

const task = spawn('ffmpeg', [
    '-i',
    'C:\\Software Development\\ffmpeg\\blackpink.mp4',
    '-filter_complex_script',
    'C:\\Software Development\\project\\filter.txt',
    '-c:v',
    'libx264',
    '-preset',
    'ultrafast',
    '-pix_fmt',
    'yuv420p',
    '-c:a',
    'libopus',
    '-progress',
    '-',
    'output.mp4',
    '-y'
], {
    cwd: 'C:\\Software Development\\ffmpeg'
});

task.stdout.on('data', data => { 
    console.log(data.toString())
})


  


• Batch interval screenshot with timestamps

  7 juin 2019, par doko

  I’m trying to make a script to batch screenshot videos per an interval with bash and ffmpeg (e.g. 1 screenshot per second)
  But the problem is that ffmpeg doesn’t have an option to output the frames with filenames containing their timestamp within the video (not local computer time).

  I’ve found some hacky solutions to do this, but they’re all pretty buggy, inaccurate and doesn’t work in all use cases (such as videos with variable framerate)

  So are there better solutions or tools to do this kind of task ?

  #!/bin/bash
  
  for i in *.$1; do #define video extension
  
  if [ ! -d "$PWD/${i%.*}" ]; then #if directory does not exist yet
  
      mkdir -p "${i%.*}" #create folder based on filename
  
      ffmpeg -i "$i" -vf fps="1/$2" "$PWD/${i%.*}/${i%.*}.%04d.png" #output screenshots
  
  fi
  
  done

  EDIT :
  I remade my script based on Gyan’s answer

  If anyone with more expertise can point out any mistakes, please do so.

  #!/bin/bash
  
  #./batch_screenshot.sh [video format] [screenshot interval in seconds]
  
  #given video1.mp4, video2.mp4, etc. within a directory, script will output the video screenshots to folders called video1, video2, etc. with the image filename of video1 - HH-MM-SS.png, video2 - HH-MM-SS.png, etc.
  
  orig="$PWD"
  
  for i in *.$1; do
  
      if [ ! -d "$PWD/${i%.*}" ]; then #if directory does not exist yet
  
          mkdir -p "${i%.*}" #create them
  
          ffmpeg -i "$i" -vf select="floor(t*1/$2)-floor(prev_t*1/$2)" -r 1000 -vsync 0 -frame_pts true "$PWD/${i%.*}/%d.png" #output screenshots
  
          cd "$PWD/${i%.*}"
  
          for r in *.png; do #batch rename all the output files
  
              seconds=$(( "${r%.*}" / 1000 )) #convert miliseconds in filename to seconds
  
              timestamp=$(date -d@"$seconds" -u +%H-%M-%S) #convert seconds to hh:mm:ss format
  
              mv "$r" "${i%.*} - $timestamp.png" #rename
  
          done
  
          cd "$orig"
  
      fi
  
  done

• Revision f069335e8811d8f8250facaf6da284b039a86e10 : SQLite fait une division entiere sur le timestamp, il en resulte une date ...

  11 octobre 2010, par Cerdic — Log

  SQLite fait une division entiere sur le timestamp, il en resulte une date arrondie au jour precedent, malgre le ceil qui suit. On reformule avec un floor qui devrait marcher dans tous les SQL git-svn-id : svn ://trac.rezo.net/spip/branches/spip-2.1@16474 (...)