AUSTIN, Texas » Music festivals are booming, and so is one alternative to paying soaring ticket prices to spend a long weekend packed among 50,000 or more typically sweaty concertgoers: watching the performances online for free.

At the Austin City Limits Music Festival, about a third of the nearly 130 bands on a lineup that includes the Red Hot Chili Peppers, the Black Keys and Jack White will have their sets broadcast on YouTube. That’s a record for the three-day festival that starts Friday. Just six years ago organizers began webcasting with a single feed and struggled to persuade artists to even participate.

The same was once true at trendsetters like Bonnaroo and Lollapalooza. But as Austin City Limits marks the unofficial end of the big-festival calendar in the U.S. for 2012, this year might also go down as the year when live-streams started crossing into mainstream.

Take the year’s most talked-about performance: Tupac Shakur rising from the dead as a hologram at the Coachella Valley Music and Arts Festival in a resurrection that was live-streamed from the California desert and talked about around the world.

The rock band Delta Spirit will be among the first acts up on Austin City Limit’s YouTube channel.

"It’s never going to equal seeing it live. But it’s cool that it engages more people," Delta Spirit lead singer Matt Vasquez said. "We’re a generation of content, aren’t we? We love to fill up our days with as little space as possible."

Promoters aren’t trying to sell live-streaming as a substitute for the you-had-to-be-there experience of concerts. Especially since, in many cases, you still very much have to be there to catch some of the biggest headliners: Neil Young & Crazy Horse and Weezer are among the performers in Austin this weekend whose sets won’t be broadcast on the Web.

Nor do live-steams pose any threat to attendance or profits. Three-day passes for Austin City Limits this year ran for $200 and sold out within an hour of the day the full lineup was announced.

But festival live-streaming has come a long way in a short time, even by technology standards. Organizers of the country’s biggest music festivals declined to reveal the size of their online audiences. But at C3 Presents, which puts on Lollapalooza and Austin City Limits, the number of live-stream viewers has climbed into the "high millions," said Courtney Trucksess, director of sponsorship.

At Bonnaroo, which began live-streaming around the same time as Austin City Limits, there’s been a "big increase" in views and the amount of time each user spends watching, said Jonathan Mayers, co-founder of Superfly Presents, which produces the four-day Tennessee festival.

"We’ve seen the average view time is over an hour in one sitting," said Chris Roach, head of business development for AEG Digital Media, which has produced live-streaming for Coachella and other open-air concerts. "That’s a pretty engaged eyeball for an advertiser to put their dollar against."

Little fanfare surrounded webcasts when Bonnaroo and Austin City Limits began experimenting with it in 2006. Viewers back then were treated only to a handful of willing artists, partial sets and about eight hours a day of video. Bandwidth was an issue and the single feed was streamed exclusively through the website of a corporate sponsor.

This year, Coachella had three live-stream channels. Austin City Limits will have multiple channels, too, and the production has increasingly taken on the polish of a live television broadcast.

But not all bands remain convinced, and organizers say there are artists and labels reluctant to have their performances streamed online. Trucksess says "it’s still a hurdle."

"At the end of the day, you’re putting yourself out there," Trucksess said. "Are people going to watch? What if, God forbid, you mess up your lyrics or have a bad performance? Maybe that’s the one time that they felt like they had a bad show."

Vasquez said he noticed himself looking "totally exhausted" after going back to watch his own performance at Lollapalooza last year. Maybe not ideal, but webcasts also create something of a historical archive. Vasquez recalled a conversation with a member of My Morning Jacket after the band’s live-streamed show at Austin City Limits last year.

"He told me, ‘I think this might be the best show we’ve ever played,"’ Vasquez said. "And because it’s all recorded and on YouTube, there’s My Morning Jacket having the set of their entire life. That’s amazing."

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Online:

http://aclfestival.com

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Follow Associated Press writer Paul J. Weber: www.twitter.com/pauljweber .