Andy Samberg, Akiva Schaffer, and Jorma Taccone are masters of the music video parody, and their SNL shorts “D*** in a Box,” “Jack Sparrow,” and “I’m on a Boat,” all featuring genuine music stars, followed the first true viral video, the classic “Lazy Sunday.” They are gifted at composing catchy hooks, writing silly lyrics, and nailing the music and look of genres from rap to pop to R&B. With appealing targets and a three-minute running time, they did very well. Now they’ve produced, written, and starred in a feature length parody of music documentaries with “Popstar: Never Stop Never Stopping.” So, instead of comparing them to the performers they take on with their video shorts, they are going up against films like “This is Spinal Tap” and “Walk Hard,” both of which managed the daunting challenge of being more over-the-top than the acts they were parodying. “Popstar” is pleasant enough, but does not quite meet that challenge, getting most of its energy and most of its laughs from an endless parade of celebrity cameos, mostly winking at the audience.

Samberg plays Conner, once part of a popular band called Style Boyz with his childhood friends Owen (Taccone) and Lawrence (Schaffer), and now a hugely successful solo performer known as Conner4Real. Owen is now reduced to serving as DJ. Taccone provides the film’s rare subtle charms, making Owen so endearing he deserves his own movie. On stage, he sits behind an impressive high-tech set-up, but as he explains in one of the film’s comic high points, everything is set up on his iPod, which also has room for the audio books he listens to on the road. He makes the best of his relegation to the sidelines, even when Conner decides that he should have to wear a huge, heavy electro helmet/mask that shoots a zillion-watt light beam out of the top, so powerful it could probably disrupt the navigation system of the space station.

Lawrence is furious with Conner for stealing the credit he felt he deserved for one of his biggest hits. He has retreated to a farm in Colorado, where he makes terrible wood carvings and broods about the unfairness of it all. That hit, by the way, in a shrewd jab at the recording industry and its fans, turns out to be a brief rap segment in a song by a superstar (a blink-and-you’ll-miss her Emma Stone). Connor tells us that most rap artists do catchphrases, but his innovation (actually Lawrence’s) was to do a lot of catchphrases.

Conner is, of course, dating a starlet (Imogen Poots) and decides to distract the press from the terrible reviews of his new album by proposing to her in a stunt that goes terribly wrong. When ticket sales for his tour lag, he brings on an opening act, an up-and-coming rapper (Chris Redd) who “All About Eve”-style begins as a fan and then starts to take over the show.

The trio gets able support from SNL veterans Tim Meadows, Maya Rudolph, and Joan Cusack, and there are some funny cutaways to a TMZ-style sleazy “news” organization, but at a brisk under-90 minute running time no one is on screen for very long. The musical numbers are hilarious and the film is never mean-spirited about its characters or the real-life celebrities it is parodying. And by the time you figure out a joke isn’t working, two more have gone by, the pace itself enough things bouncing along. It tries so hard to entertain you, it would be hard-hearted not to give in.

Parents should know that this film includes very explicit nudity, very strong and crude language, sexual references, some comic violence, drinking, and drugs.

Family discussion: What celebrities does this remind you of? Why did Conner decide he wanted someone to be honest with him?

If you like this, try: “This is Spinal Tap,” “Walk Hard,” “Gentle and Soft” (the brilliant Bill Hader/Fred Armison mockumentary about a 70’s soft rock duo) and the Lonely Island videos