ohif-viewer/Packages/viewerbase/client/components/viewer/playClipButton/playClipButton.html

<template name="playClipButton">
    <div id="{{this.id}}"
         class="toolbarSectionButton rp-x-1 {{this.classes}} {{activeClass}} {{#if isPlaying}}active{{/if}}"
         title="{{this.title}}">
        <div class="svgContainer">
            {{#if isPlaying}}
                <i class="fa fa-stop fa-fw"></i>
            {{else}}
                <i class="fa fa-play fa-fw"></i>
            {{/if}}
        </div>
        <div class="buttonLabel">
            {{#if isPlaying}}Stop{{else}}Play{{/if}}
        </div>
    </div>
</template>