PHOTO: Leo Herrera

One couple, two channels: Adrian and Deirdre Roberts love to combine music, even the bootlegged kind.

A skull and crossbones flies today over the mashup, the world’s newest form of pop music. Like the punk rock revolution it harks back to, it has an outlaw do-it-yourself ethos, but this time around, instead of electric guitars and torn clothing, the crucial component is software.

A mashup consists of overlaid (and typically illegally sampled) snippets of preexisting songs. The best ones offer up equal parts musical parody and dance-floor-filling cheeky commentary—think the “Imperial Theme” from The Empire Strikes Back colliding with Middle Eastern–flavored techno from electronica artists The Chemical Brothers.

The form’s tireless evangelists are DJs Adrian and the Mysterious D, otherwise known as Adrian and Deirdre Roberts, ­husband-and-wife producers based in San Francisco. They host a monthly party called Bootie (for “bootleg”) in San Francisco, Los Angeles, New York, and the online virtual world Second Life. Here they play both their own material and some of the top mashups from around the world, as culled from Web sites like Mashup Charts (http://mashup-charts.com) and Mashupciti (http://mashupciti.com). Sister Bootie events have also cropped up in Mexico City, Munich, and Paris. The events are listed at http://bootieusa.com.

Both husband and wife are avid music fans with omni­vorous tastes. Adrian is the techie one, having earned a bachelor’s degree in radio and television and worked in both audio and video since the late 1980s. He says the key to making a mashup is ­mastering an off-the-shelf music-mixing program, such as Sony ACID Pro (Windows) or Ableton Live (Mac). Audacity, an open-source program, is a good, simple, and free alternative.

“Very rarely does a good mashup come together effortlessly,” Adrian says. “It’s not just slapping a vocal track on top of an instrumental and calling it a day.” Merging many songs seamlessly into a new ­composition, particularly one that takes on new meaning as satire or ­commentary, can require days or weeks in the studio. Some particularly ambitious producers add video too. “Usually, the audio part is done first, and then ­videos of the songs that are mashed up are edited together to sync up with the audio,” he says.

Of course, it all begins with the hunt for raw material—the most challenging part of which is ­locating unadorned vocal tracks. One trick, Adrian says, is to comb through bands’ videos or ­concerts on DVD. He says that if the music was produced in Dolby 5.1 Surround, you often find the vocals in the center channel.

Some artists also release a cappella versions of their songs, encouraging fans to mash it up. The most famous example is a Jay-Z Black Album/Beatles’ White Album mashup, The Grey Album. In 2003, rapper and hip‑hop mogul Jay-Z released an a ­cappella ­version of The Black Album, encouraging remixers and mashup artists to mix his vocals into others’ music. When New York DJ Danger Mouse (Brian Burton) released The Grey Album online in 2004, it provoked a cease-and-desist letter from the Beatles’ recording label, EMI-Capitol.

The mashup underground views such a letter as a badge of honor, says Deirdre. For those of a less buccaneering nature, though, such a letter may come as a bit of a shock. But don’t worry—if you’re doing it strictly for private enjoyment, your behavior would be actionable only under the most draconian legal interpretation, says Paul Rapp, an expert on copyright at Albany Law School, in New York state. It would be like suing ­children for singing “Happy Birthday to You”—still under copyright after all these years. Those who should beware, Rapp says, are mashup producers who take their material onto the Internet and establish a cult following.

Until the courts begin to rule on how mashups fit into the fair use provisions of copyright law, ­establishing what’s legal and what’s not, DJs A+D say they’re happy to continue dancing their delicate dance through the world’s popular music catalog, Jolly Roger hoisted high.