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• Reading colors encoded in image at a position changes its value after decoded from video using php and ffmpeg

  29 novembre 2022, par Jeenus Junanio

  I created a piece of code to encode unique color on image and converted the image to PNG so that it would be lossless. After This I created a video with the frame using this image using the ffmpeg in php shellexec(). After saving this video I reopened it to extract the frmae image added and tried to read those values from the image. Now the values on the image are a bit changed.

  


  Here is the code that I tried to create the video :

  


  $canvas = imagecreatefromjpeg('translate/first_frame.jpg');
        // create a random color
        $rand = str_pad(dechex(rand(0x000000, 0xFFFFFF)), 6, 0, STR_PAD_LEFT);
        $dec_color= hexdec($rand);

        // add the new color to image

        for ($i=0; $i < 24; $i++) { 
           imagesetpixel($canvas,$i,0,$dec_color);
        }

        // store the image and close the file opened

        // $filename = 'translate/test/output.png'; 
        $filename = 'translate/test/output.bmp'; 

        // imagepng($canvas, $filename);
        imagebmp($canvas, $filename);

        imagedestroy($canvas);

        $frame      = $filename; // an image(png,gif,etc)
        $audio      = 'translate/output/audio/abcdefghijklmnopqrstuvwxya.mp3';
        $output     = 'translate/output/video/'.time().'.mp4';   

        $cmd = 'ffmpeg -loop 1 -y -i '.$frame.' -i '.$audio.' -c:v libx264 -tune stillimage -c:a copy -shortest '.$output;
        shell_exec($cmd);


  


  This above code is creating the video with the image.

  


  Now I tried to extract the image video and color from image, the colors are a bit changed.

  


  if($request->hasFile(&#x27;video&#x27;)){&#xA;            $file = $request->file(&#x27;video&#x27;);&#xA;            $filename = $file->getClientOriginalName();&#xA;            $path = public_path(&#x27;translate/test/&#x27;);&#xA;        }else{&#xA;            return &#x27;No file uploaded&#x27;;&#xA;        }&#xA;        &#xA;        &#xA;        if ($file->move($path, $filename)) {&#xA;            $video = &#x27;translate/test/&#x27;.$filename;&#xA;        }else{&#xA;            return &#x27;error file upload&#x27;;&#xA;        }&#xA;&#xA;       &#xA;        // $output = &#x27;translate/output/image/&#x27;.time().&#x27;.png&#x27;;&#xA;        $output = &#x27;translate/output/image/&#x27;.time().&#x27;.bmp&#x27;;&#xA;        // $output = &#x27;translate/output/image/&#x27;.time().&#x27;.jpg&#x27;;&#xA;&#xA;        $cmd = &#x27;ffmpeg -i &#x27;.$video.&#x27; -vframes 1 &#x27;.$output;&#xA;        shell_exec($cmd);&#xA;&#xA;&#xA;// $dimg = imagecreatefrompng($output);&#xA;        $dimg = imageCreateFromBmp($output);&#xA;        // $dimg = imagecreatefromjpeg($output);&#xA;&#xA;        $extracted_color = array();&#xA;&#xA;        for ($x=0; $x &lt; 24 ; $x&#x2B;&#x2B;) { &#xA;          $extracted_color[]= imagecolorat($dimg, $x, 0);&#xA;        }&#xA;&#xA;        echo "<br />Retrived colors:<pre>".print_r($extracted_color,1)."</pre>";&#xA;&#xA;        imagedestroy($dimg);&#xA;&#xA;&#xA;&#xA;

  


  The color added was 44743072 but the colors retrieved are 4539914,4474121,4408072,4408326 from x=0,y=0 to x=24,y=0.

  


  In both PNG and BMP I am loosing the added pixels. You can clearly see in my code i have commented the code for png to read the image as bmp.

  


  Can someone let me know if I miss anything here.

  


• ffmpeg wasm - how to take client-side created mp4 and upload it to the same server hosting the index/js files being used

  29 juillet 2022, par John Farrell

  Ok, so Im an IT guy and kind of a noob on the dev side of the fence. But I've been able to create this ffmpeg wasm page that takes a canvas and converts it to webm / and .mp4 — what i WANT to do is take the resulting .mp4 file and upload it to the server where the page/js are being served from. is this possible ? I will include my source code which is fairly simple and straight forward, I just don't know how to manipulate the resulting mp4 file that ffmpeg spits out (i realize it is happening client side) to be able to push it up to the server (maybe with aupload.php type situation ?) the solution can be html/java/php whatever, so long as it takes the mp4 output and gets it onto the server. I'd VERY MUCH appreciate a hand here.

  


  Going to try my best to properly insert the html and js. please bear with me if i've done something wrong, i've never had to -ask- a question on here, usually just look up existing answers.

  


  


  


  const { createFFmpeg } = FFmpeg;
const ffmpeg = createFFmpeg({
  log: true
});

const transcode = async (webcamData) => {
  const message = document.getElementById('message');
  const name = 'record.webm';
  await ffmpeg.load();
  message.innerHTML = 'Start transcoding';
  await ffmpeg.write(name, webcamData);
  await ffmpeg.transcode(name,  'output.mp4');
  message.innerHTML = 'Complete transcoding';
  const data = ffmpeg.read('output.mp4');

  const video = document.getElementById('output-video');
  video.src = URL.createObjectURL(new Blob([data.buffer], { type: 'video/mp4' }));
  dl.href = video.src;
  dl.innerHTML = "download mp4"
}

fn().then(async ({url, blob})=>{
    transcode(new Uint8Array(await (blob).arrayBuffer()));
})

function fn() {
var recordedChunks = [];

var time = 0;
var canvas = document.getElementById("canvas");

return new Promise(function (res, rej) {
    var stream = canvas.captureStream(60);

    mediaRecorder = new MediaRecorder(stream, {
        mimeType: "video/webm; codecs=vp9"
    });

    mediaRecorder.start(time);

    mediaRecorder.ondataavailable = function (e) {
        recordedChunks.push(event.data);
        // for demo, removed stop() call to capture more than one frame
    }

    mediaRecorder.onstop = function (event) {
        var blob = new Blob(recordedChunks, {
            "type": "video/webm"
        });
        var url = URL.createObjectURL(blob);
        res({url, blob}); // resolve both blob and url in an object

        myVideo.src = url;
        // removed data url conversion for brevity
    }

// for demo, draw random lines and then stop recording
var i = 0,
tid = setInterval(()=>{
  if(i++ > 20) { // draw 20 lines
    clearInterval(tid);
    mediaRecorder.stop();
  }
  let canvas = document.querySelector("canvas");
  let cx = canvas.getContext("2d");
  cx.beginPath();
  cx.strokeStyle = 'green';
  cx.moveTo(Math.random()*100, Math.random()*100);
  cx.lineTo(Math.random()*100, Math.random()*100);
  cx.stroke();
},200)

});
}

  


  &#xA;&#xA;&#xA;<code class="echappe-js">&lt;script src=&quot;https://unpkg.com/@ffmpeg/ffmpeg@0.8.1/dist/ffmpeg.min.js&quot; defer&gt;&lt;/script&gt;&#xA;&lt;script src='http://stackoverflow.com/feeds/tag/canvas2mp4.js' defer&gt;&lt;/script&gt;&#xA;&#xA;&#xA;&#xA;here is a canvas
  &#xA;
  &#xA;&#xA;here is a recorded video of the canvas in webM format
  &#xA;
  &#xA;&#xA;&#xA;here is a transcoded mp4 from the webm above CLIENT SIDE using ffmpeg
  &#xA;
  &#xA;&#xA;
  
  &#xA;&#xA;
  

  


  


  



• Anomalie #3779 : Erreur ""Un dossier temporaire est manquant pour télécharger les fichiers"

  7 mai 2016, par Franck Dalot

  Buenos dias, :-)
  necesito mas informaciones para tratar de reproducir el problema
  version de PHP ?
  Version de spip 3.1.x ; 3.0.x ; 2.1.x ?
  Se trata de una version NATIVA o de un sitio que ,por ejemplo paso de una version 3.0.x a una version 3.10x ?
  tipo del’magen ?jpeg ?gif ?...