fix #1170

js/reveal.js

@@ -3501,7 +3501,9 @@
 
 			// If there are media elements with data-autoplay,
 			// automatically set the autoSlide duration to the
-			// length of that media
+			// length of that media. Not applicable if the slide
+			// is divided up into fragments.
+			if( currentSlide.querySelectorAll( '.fragment' ).length === 0 ) {
 				toArray( currentSlide.querySelectorAll( 'video, audio' ) ).forEach( function( el ) {
 					if( el.hasAttribute( 'data-autoplay' ) ) {
 						if( autoSlide && el.duration * 1000 > autoSlide ) {
@@ -3509,6 +3511,7 @@
 						}
 					}
 				} );
+			}
 
 			// Cue the next auto-slide if:
 			// - There is an autoSlide value