An Algorithm to Extract Looping GIFs from Videos

<i>We will say that a video segment loops well when its first and last video frames are very similar.</i><p>It&#x27;s a reasonable approximation. However really perfect loops have not only matching positions of the objects but perfect speeds too. I would calculate optical flows and compare them at the first and the last frames too and somehow put it into the distance function.<p>One example: this algorithm would find the half period of a pendulum perfectly loop. Taking optical flows into account would fix this.

some prior research on this:<p>---<p><i>Loop Findr</i> by Collin Burger<p><a href="http://loopfindr.tumblr.com/" rel="nofollow">http:&#x2F;&#x2F;loopfindr.tumblr.com&#x2F;</a><p><a href="http://golancourses.net/2014/collin/05/12/loop-findr/" rel="nofollow">http:&#x2F;&#x2F;golancourses.net&#x2F;2014&#x2F;collin&#x2F;05&#x2F;12&#x2F;loop-findr&#x2F;</a><p><a href="https://github.com/cyburgee/loopFindr" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;cyburgee&#x2F;loopFindr</a><p>---<p>Microsoft Research: <i>Automated video looping with progressive dynamism</i> (2013)<p><a href="http://research.microsoft.com/en-us/um/people/hoppe/proj/videoloops/" rel="nofollow">http:&#x2F;&#x2F;research.microsoft.com&#x2F;en-us&#x2F;um&#x2F;people&#x2F;hoppe&#x2F;proj&#x2F;vid...</a><p><a href="http://research.microsoft.com/pubs/196137/videoloops.pdf" rel="nofollow">http:&#x2F;&#x2F;research.microsoft.com&#x2F;pubs&#x2F;196137&#x2F;videoloops.pdf</a><p><a href="http://research.microsoft.com/en-us/downloads/d02f3198-7896-45eb-89e8-5a75859b67c8/" rel="nofollow">http:&#x2F;&#x2F;research.microsoft.com&#x2F;en-us&#x2F;downloads&#x2F;d02f3198-7896-...</a>

Very cool concept and article.<p>You may also notice that many of these looping gifs are done in much simpler way by just playing part of a video and then playing it in reverse.

I assume something has broken, but this article makes no sense to me. It&#x27;s full of sentences like:<p>&quot;If is very similar to , and is different from , then we do not need to compute to know that and are also very different.&quot;

With a better, faster algorithm, probably with some help from a GPU, this could become a new app. There&#x27;s already &quot;<a href="http://loopc.am/&quot;" rel="nofollow">http:&#x2F;&#x2F;loopc.am&#x2F;&quot;</a>, but it&#x27;s not as good. Then cash out by selling out to Instagram. Also use to jazz up real estate ads.

Isn&#x27;t this just k-NN? I mean: one can reduce this problem to k-NN by first loading the database with all video frames, and then performing queries using frame 0, frame 1, etc.<p>There are good tree algorithms[0] and implementations[1][2] for executing k-NN queries. These implementations also exploit the properties of the triangle inequality.<p>[0] <a href="http://en.wikipedia.org/wiki/Ball_tree" rel="nofollow">http:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Ball_tree</a><p>[1] <a href="http://mlpack.org/doxygen.php?doc=nstutorial.html" rel="nofollow">http:&#x2F;&#x2F;mlpack.org&#x2F;doxygen.php?doc=nstutorial.html</a><p>[2] <a href="http://scikit-learn.org/stable/modules/neighbors.html#neighbors" rel="nofollow">http:&#x2F;&#x2F;scikit-learn.org&#x2F;stable&#x2F;modules&#x2F;neighbors.html#neighb...</a>

Slightly misleading to say the summed colour value difference between the frames a distance that&#x27;s analogous to a geometric distance, geometric distance measures on data with high numbers of dimensions becomes useless, as the dimensionality increases the difference between &#x27;near&#x27; and &#x27;far&#x27; tends towards zero.