[SOLVED] Using amp-img tag for gif animations

Using amp-img tag for gif animations

There is <amp-anim> tag for gif animations. But I found that <amp-img> tag can show gif animations. I know <amp-anim> tag can set a placeholder, but I don't need it. And I found no defference any more.
So, my question is "Is there problem to use <amp-img> tag for gif animations?"

Open https://ampbyexample.com/playground/ and paste the html code below, if you want to check how work <amp-img> tag and <amp-anim> tag.

<!doctype html>
<html ⚡>
<head>
  <meta charset="utf-8">
  <script async src="https://cdn.ampproject.org/v0.js"></script>
  <script async custom-element="amp-anim" src="https://cdn.ampproject.org/v0/amp-anim-0.1.js"></script>
  <meta name="viewport" content="width=device-width,minimum-scale=1,initial-scale=1">
  <link rel="canonical" href="https://ampbyexample.com/components/amp-anim/">
  <style amp-boilerplate>body{-webkit-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-moz-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-ms-animation:-amp-start 8s steps(1,end) 0s 1 normal both;animation:-amp-start 8s steps(1,end) 0s 1 normal both}@-webkit-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-moz-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-ms-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-o-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}</style><noscript><style amp-boilerplate>body{-webkit-animation:none;-moz-animation:none;-ms-animation:none;animation:none}</style></noscript>
</head>
<body>

  <h2>amp-anim supports gif animation</h2>
  <amp-anim width="245" height="300" src="/img/gopher.gif" alt="an animation"
            attribution="The Go gopher was designed by Reneee French and is licensed under CC 3.0 attributions.">
  </amp-anim>

  <h2>amp-img also supports gif animation</h2>
  <amp-img width="245" height="300" src="/img/gopher.gif" alt="an animation"
            attribution="The Go gopher was designed by Reneee French and is licensed under CC 3.0 attributions.">
  </amp-img>
</body>
</html>

Solution