I have discovered that animated GIFs created using Delphi 2009's `TGIFImage` sometimes doesn't play correctly in *some* GIF viewers. The problem is that the animation is restarted prematurely.

Consider the following example:

```
program GIFAnomaly;

{$APPTYPE CONSOLE}

uses
  Windows, Types, Classes, SysUtils, Graphics, GIFImg;

var
  g: TGIFImage;
  bm: TBitmap;

procedure MakeFrame(n: integer);
var
  x: Integer;
  y: Integer;
begin
  for x := 0 to 256 - 1 do
    for y := 0 to 256 - 1 do
      bm.Canvas.Pixels[x, y] := RGB((x + n) mod 255,
        (x + y - 2*n) mod 255, (x*y*n div 500) mod 255);
end;

var
  i: integer;

begin

  bm := TBitmap.Create;
  bm.SetSize(256, 256);

  g := TGIFImage.Create;
  g.Animate := true;
  for i := 0 to 499 do
  begin
    MakeFrame(i);
    TGIFGraphicControlExtension.Create(g.Add(bm)).Delay := 3;
    Writeln('Creating frame ', i+1, ' of 500.');
  end;
  TGIFAppExtNSLoop.Create(g.Images.Frames[0]).Loops := 0;

  g.SaveToFile('C:\Users\Andreas Rejbrand\Desktop\test.gif');

end.

```

(This is the simplest example I could find that exhibits the problem.)

The output is a rather large animated GIF. In Internet Explorer 11, the entire 15-second 'movie' is played properly, but in Google Chrome the 'movie' is prematurely restarted after only about four seconds.

Why is this?

1. Is there something wrong with the output GIF file?
2. If so, is there something wrong with my code above, or is there a problem with `GIFImg`?
3. If not, what is the nature of the problem in the viewer? What fraction of the available viewers have this problem? Is there a way to 'avoid' this problem during GIF creation?

For the benefit of the SO user, the above code is a minimal working example. Of course, I wasn't creating these psychedelic patterns when I discovered the issue. Instead, I was working on a Lorenz system simulator, and produced this GIF animation which does play in IE but not in Chrome:

![Sample GIF animation displaying the issue](https://privat.rejbrand.se/lorenz50.gif)

In Internet Explorer 11, the model is rotated 360 degrees before the animation is restarted. In Google Chrome, the animation is restarted prematurely after only some 20 degrees.

* The Lorenz image **works** in Internet Explorer 11.0.9600.17239, The GIMP 2.8.0, Opera 12.16
* The Lorenz image **does not work** in Google Chrome 36.0.1985.143 m, Firefox 26.0, 27.0.1, 31.0.

If I open a 'problematic' GIF in The GIMP and let GIMP (re)save it as an animated GIF, the result works in every viewer. The following is the GIMPed version of the Lorenz animation:

![Sample GIF animation that has been GIMPed](https://privat.rejbrand.se/lorenz50_GIMPed.gif)

Comparing the two files using a hex editor, and using [the Wikipedia article](https://en.wikipedia.org/wiki/GIF#Animated_GIF) as a reference, it seems, for instance, like the 'NETSCAPE' string is at the wrong place in the original (unGIMPed) version. It is somewhat strange, that even if I set the `width` and `height` of the GIF image, the corresponding values in the Logical Screen Descriptor are not there.