grittycity_wide-36581687faa6a5727bfbd02f9401983820dde059-s5-c30After 35 years or so on TV, “48 Hours” (CBS, 9 p.m.) specialized in true crime stories. Tonight, it expands — into two hours — in order to accommodate a feature length documentary by one of the show’s editors, Richard Barber, who spent the last several years filming his work.

“The Whole Gritty City” follows three New Orleans marching bands as they prepare students to marchin the Mardi Gras parades. in addition to music appreciation, band practice introduces structure and safety into their lives. yes it sounds like a story line in “Treme,” but its an unnarrated documentary with an introduction by Wynton Marsalis. A Saturday night showcase for documentaries is a good use of the “48 Hours” format.

The Winter Olympics (NBC, 8 p..m.) continues to dominate primetime. Tonight is the Alpine skiing women’s super G final, and finals in men’s short track, men’s speed skating and men’s ski jumping.

But there’s big doings on cable as part of the NBA All-Star Saturday Night (TNT, 8:30 p.m.) with the annual slam dunk contest, three point shootout and skills challenge. The NBA Tip Off” (TNT, 8 p.m.) kicks things off.

Josh Brolin, Ryan Gosling, Nick Nolte, Emma Stone, and Sean Penn star in the 2013 action crime film “Gangster Squad” (HBO, 8 p.m.), making its premium cable debut. Also on tonight is another crime thriller, 2012’s “Alex Ross” (Showtime, 8 p.m.) starring Tyler Perry and Matthew Fox.

Annie Heise stars in the new TV film “The Good Mistress” ( Showtime, 8 p.m.) as a new woman in town who has a one night stand with a stranger who she learns is her friend’s husband.

The ninth season premiere of “Ghost Adventures” (Travel, 9 p.m.) gets into the house where Sharon Tate was killed.

An additional 35 episodes have been ordered for “Sex Sent Me tothe ER” (TLC, 10 p.m.). Are there that many people with this problem?

Oscar’s best picture nominees from 1929/1930 are on Turner Classic Movies, with “All Quiet in the Western Front” (8 p.m.), which won, as well as “The Big House” (10:30 p.m.), “The Divorcee” (12:15 a.m.), “The Love Parade” (2 a.m.) and “Disraeli” (4 a.m.).

Other movies tonight include “Dreamgirls” (ABC, 8 p.m.), “Grease” (ABC Family, 8 p.m.), “Snakes on a Plane” (AMC, 8 p.m.) and “Eternal Sunshine of the Spotless Mind” (Sundance, 9 p.m.).

Men’s college hoops today includes Pittsburgh at North Carolina (CBS, 1 p.m.), Xavier at Marquette (Fox, 4 p.m.), Brigham Young at Saint Mary’s (ESPN2 8 p.m.) and Florida at Kentucky (ESPN, 9 p.m.).

Olympics mean no “Saturday Night Live” but Arcade Fire plays an old “Austin City Limits” (PBS, 9 p.m., check local listings.