Not feature-length but worth seeking out is "Remembering the Artist: Robert De Niro, Sr.," for including the most candid, intimate moments you'll ever hear from the Oscar-winning actor who is the artist's son.

The other main doc theme this year, as always, are films that cluster around society and social issues. Some of the most memorable this year include:

"The Case Against 8." An engrossing and emotional examination of the way the case against California's anti-gay-marriage Proposition 8 was put together.

PHOTOS: Box office top 10 of 2013

"Dinosaur 13." The inside story of how a Tyrannosaurus rex named Sue turned the world of paleontology upside down.

"Happy Valley." A thoughtful, surprising and devastating film that looks beneath the surface of the Jerry Sandusky Penn State child abuse scandal.

"Last Days of Vietnam." An accomplished examination of the logistical and moral dilemmas of our exit from Vietnam.

"Marmato." Made with exceptional artistry and detailing what happens when a major Canadian firm comes to a small Colombian town that's been mining gold its own way for 500 years.

"The Overnighters." A small North Dakota town becomes ground zero for the fracking gold rush. A film about hope, acceptance and the limits of the American dream that will throw you for a loop.

Finally, there are a pair of unclassifiable docs that just make you feel good for completely different reasons. "Alive Inside" shows the almost miraculous effect music has on catatonic dementia sufferers, and "The Battered Bastards of Baseball" is a rollicking tale of how an independent baseball team spread joy in 1970s Portland, Ore. Enjoyment can be hard to find at Sundance, so take it where you can.

kenneth.turan@latimes.com