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• WMA Lossless and ProRes Encoder

  4 mars 2012, par Multimedia Mike — General

  The projects (FFmpeg / Libav) just got a WMA lossless decoder. For those keeping score, this means that there are open source methods for decoding every single one of Microsoft’s proprietary audio codecs (Windows Media Audio, or WMA) : WMA v1, WMA v2, WMA9/Pro, WMA Voice, and now WMA lossless. Currently, it’s only advertised to decode 16-bit audio (no 24-bit). Also, when I first tried it a few days ago, it didn’t decode the very end of the single sample file I concocted many years ago (luckynight.wma). But that might be cleared up by now.

  Some other recent developments in the projects that I wanted to call out : An encoder for the Apple ProRes encoder from Kostya ; XWD (X window dump) image decoding and encoding from Paul B. Mahol ; a Sun rasterfile encoder from Aneesh Dogra.

  And then there’s the new playback system for CDXL files, also courtesy of Paul B. Mahol. I wasn’t familiar with this format until I wrote this post, which is surprising, given the format’s vintage. This was a CD-ROM FMV format favored for Amiga computers. Here it is in all its 160x120x10fps glory :

  
  
  

  That’s the amigaball.cdxl sample available in the repository. The sample is 3835910 bytes large and plays for about 24 seconds. This yields a data rate of about 159 kbytes/second. So, yeah, single-speed CD-ROM FMV.

• Dreamcast Operating Systems

  16 septembre 2010, par Multimedia Mike — Sega Dreamcast

  The Sega Dreamcast was famously emblazoned with a logo proudly announcing that it was compatible with Windows CE :

  
  
  

  It’s quite confusing. The console certainly doesn’t boot into some version of Windows to launch games. Apparently, there was a special version of CE developed for the DC and game companies had the option to leverage it. I do recall that some game startup screens would similarly advertise Windows CE.

  Once the homebrew community got ahold of the device, the sky was the limit. I think NetBSD was the first alternative OS to support the Dreamcast. Meanwhile, I have recollections of DC Linux and LinuxDC projects along with more generic Linux-SH and SH-Linux projects.

  
  
  

  DC Evolution hosts a disc image available for download with an unofficial version of DC Linux, assembled by one Adrian O’Grady. I figured out how to burn the disc (burning DC discs is a blog post of its own) and got it working in the console.

  It’s possible to log in directly via the physical keyboard or through a serial terminal provided that you have a coder’s cable. That reminds me– my local Fry’s had a selection of USB-to-serial cables. I think this is another area that is sufficiently commoditized that just about any cable ought to work with Linux out of the box. Or maybe I’m just extrapolating from the experience of having the cheapest cable in the selection (made by io connect) plug and play with Linux.

  
  
  

  Look ! No messy converter box in the middle as in the Belkin case. The reason I went with this cable is that the packaging claimed it was capable of up to 500 Kbits/sec. Most of the cables advertised a max of 115200 bps. I distinctly recall being able to use the DC coder’s cable at 230400 bps a long time ago. Alas, 115200 seems to be the speed limit, even with this new USB cable.

  Anyway, the distribution is based on a 2.4.5 kernel circa 2001. I tried to make PPP work over the serial cable but the kernel doesn’t have support. If you’re interested, here is some basic information about the machine from Linux’s perspective, gleaned from some simple commands. This helps remind us of a simpler time when Linux was able to run comfortably on a computer with 16 MB of RAM.

  Debian GNU/Linux testing/unstable dreamcast ttsc/1
  dreamcast login : root
  
  Linux dreamcast 2.4.5 #27 Thu May 31 07:06:51 JST 2001 sh4 unknown
  Most of the programs included with the Debian GNU/Linux system are
  
  freely redistributable ; the exact distribution terms for each program
  
  are described in the individual files in /usr/share/doc/*/copyright
  Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
  
  permitted by applicable law.
  dreamcast : # uname -a
  
  Linux dreamcast 2.4.5 #27 Thu May 31 07:06:51 JST 2001 sh4 unknown
  dreamcast : # cat /proc/cpuinfo 
  
  cpu family : SH-4
  
  cache size : 8K-byte/16K-byte
  
  bogomips : 199.47
  Machine : dreamcast
  
  CPU clock : 200.00MHz
  
  Bus clock : 100.00MHz
  
  Peripheral module clock : 50.00MHz
  dreamcast : # top -b
   09:14:54 up 14 min,  1 user,  load average : 0.04, 0.03, 0.03
  
  15 processes : 14 sleeping, 1 running, 0 zombie, 0 stopped
  
  CPU states :   1.1% user,   5.8% system,   0.0% nice,  93.1% idle
  
  Mem :     14616K total,    11316K used,     3300K free,     2296K buffers
  
  Swap :        0K total,        0K used,        0K free,     5556K cached
    PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
  
    219 root      18   0  1072 1068   868 R     5.6  7.3   0:00 top
  
      1 root       9   0   596  596   512 S     0.0  4.0   0:01 init
  
      2 root       9   0     0    0     0 SW    0.0  0.0   0:00 keventd
  
      3 root       9   0     0    0     0 SW    0.0  0.0   0:00 kswapd
  
      4 root       9   0     0    0     0 SW    0.0  0.0   0:00 kreclaimd
  
      5 root       9   0     0    0     0 SW    0.0  0.0   0:00 bdflush
  
      6 root       9   0     0    0     0 SW    0.0  0.0   0:00 kupdated
  
      7 root       9   0     0    0     0 SW    0.0  0.0   0:00 kmapled
  
     39 root       9   0   900  900   668 S     0.0  6.1   0:00 devfsd
  
     91 root       8   0   652  652   556 S     0.0  4.4   0:00 pump
  
     96 daemon     9   0   524  524   420 S     0.0  3.5   0:00 portmap
  
    149 root       9   0   944  944   796 S     0.0  6.4   0:00 syslogd
  
    152 root       9   0   604  604   456 S     0.0  4.1   0:00 klogd
  
    187 root       9   0   540  540   456 S     0.0  3.6   0:00 getty
  
    201 root       9   0  1380 1376  1112 S     0.0  9.4   0:01 bash
  

  Note that at this point I had shutdown both gpm and inetd. The rest of the processes, save for bash, are default. The above stats only report about 14 MB of RAM ; where are the other 2 MB ?

  dreamcast : # df -h
  Filesystem            Size  Used Avail Use% Mounted on
  /dev/rd/1             2.0M  560k  1.4M  28% /
  

• 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);