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• Javascript sync images

  26 septembre 2021, par Ruan Matt

  I'm studying about FPS, animations, image processing in order to get into the game development world.

  


  I took a video and extract each frame into a .jpg image, and I want to run these images, side by side, in the same sync as the original video

  


  You can test at this link => https://jsfiddle.net/ruanmatt144/267erymL/2/

  


  The problem : The video FPS is 30, but even if I put 1000/30, or any other value that refers to the original FPS, it doesn't work ! It doesn't stay in sync. setTimeout has a limit on decimal places that I don't know about ?

  


  Video timestamp for each frame => https://unity-animation.ztech.gq/timestamp.txt

  


  How can I sync those images following the original video timestamp ? Thank you.

  


  var arr = Array();
var v = 0;
var v2 = 0;
var k = 0;

(function getImages(i) {
  setTimeout(function() {
    v++;
    var r = Math.random();
        loadImage("https://unity-animation.ztech.gq/frames/out-" + v + ".jpg?v=" + r);
        arr.push("https://unity-animation.ztech.gq/frames/out-" + v + ".jpg?v=" + r);

        if (--i) getImages(i);
  }, 30)
})(20000);



const loadImage = src =>
    new Promise((resolve, reject) => {
        const img = new Image();
        img.onload = () => resolve(img);
        img.src = src;
    })  
;

var imgArray = new Array();
setTimeout(function() {
    (function runVideo(i) {
        setTimeout(function() {
            v2++;
            imgArray[v2] = new Image();
            document.getElementById('load').appendChild(imgArray[v2]);

            imgArray[v2].src = arr[v2];
            imgArray[v2].classList.add("overlayImage");
            imgArray.shift();
            var parent = document.querySelector("#load");
            [...parent.children].slice(0,-10).forEach(parent.removeChild.bind(parent));
            var last = document.querySelector('#load img:last-child').getAttribute("src");
            var _final = last.substring(
                last.indexOf("-") + 1, 
                last.lastIndexOf(".jpg")
            );
            arr.shift();
        if (--i) runVideo(i);
      }, 90) // <== the problem is here, which value I must use?
    })(38194);
    document.getElementById("video").play();
}, 20000);


  


• fftools/ffplay : don't disable x11 compositing

  26 octobre 2021, par Zane van Iperen

  fftools/ffplay : don't disable x11 compositing
  Prevents desktop stutters caused by the change (specifically on KDE).
  
  We're not a game, we don't actually need it disabled.
  Reviewed-by : Marton Balint <cus@passwd.hu>
  
  Signed-off-by : Zane van Iperen <zane@zanevaniperen.com>
  

  • [DH] fftools/ffplay.c

• Writing linear float range to openEXR turns out non linear

  3 avril 2022, par Chryfi

  I am writing the linearized depth buffer of a game to openEXR using FFmpeg. Unfortunately, FFmpeg does not adhere to the openEXR file specification fully (like allowing unsigned integer for one channel) so I am writing one float channel to openEXR, which is put into the green channel with this command -f rawvideo -pix_fmt grayf32be -s %WIDTH%x%HEIGHT% -r %FPS% -i - -vf %DEFVF% -preset ultrafast -tune zerolatency -qp 6 -compression zip1 -pix_fmt gbrpf32le %NAME%_depth_%d.exr.

  


  The float range is from 0F to 1F and it is linear. I can confirm that the calculation and linearization is correct by testing 16 bit integer (per pixel component) PNG in Blender compositor. The 16 bit integer data is written like this short s = (short) (linearzieDepth(depth) * (Math.pow(2,16) - 1)) whereas for float the linearized value is directly written to OpenEXR without multiplying with a value.

  


  However, when viewing the openEXR file it doesn't have the same "gradient" as the 16 bit png... when viewing them side by side, it appears as if the values near 0 are not linear, and they are not as dark as they should be like in the 16 bit png.
(And yes, I set the image node to linear), and comparing it with 3d tracking data from the game I cant reproduce the depth and cant mask things using the depth buffer where as with the png I can.

  


  How is it possible for a linear float range to turn out so different to a linear integer range in an image ?