Everyone has a pet song in Rock Band, and it’s inevitable that your favorite track will be someone else’s most hated. And let’s face it — in this case, if the music sucks, so does the game. Finding the best songs for the majority of the audience is an impossible trick — but what’s Eric Brosius going to do? As the audio director for Harmonix, it’s his freakin’ job.

“We look for a bunch of different things,” says Eric. “Ideally, every song would be a giant hit, have four playable parts that are really fantastic, be challenging for every instrument, and be kickass in every way. That doesn’t always happen. Some songs we get because they’re a big hit and everyone loves them. Others we choose because they’re a little more underground, and you say, ‘People should know about this song.’ Others we pick for particular parts — a killer drum- and bassline or a great guitar solo. In general, we look for something that has four interesting parts to play — a good balance of repetition and variety, so that each part will have something cool to do.”

“We also look for those songs that have ‘band moments’ — moments where it feels like everyone’s together. You play a verse, a chorus, a verse, a chorus, and there’s a breakdown, and someone screams and everybody jumps back in with a giant power chord. That’s really fun. When you look around the room, you see everyone jump up in the air and smile.”

So how do you make everyone jump and smile? Very carefully, and with a lot of patience. Eric walked us through the process of bringing Rock Band magic to the masses.

Step 1: Brainstorming
As Lynyrd Skynyrd’s Ronnie Van Zandt famously shouted before the live version of “Free Bird,” “What song do y’all wanna hear?” Eric begins the song-selection process by scouring fansites and forums for suggestions. Armed with a 3,000-song database, he analyzes, grades, and breaks the list down to 50 to 80 songs for a larger committee to debate. They in turn discuss, campaign, and otherwise whittle down the list to a “dream list” of about 40 tracks or bands (“Sometimes it’s not even specific songs — we want something by that artist”), regardless of whether those songs would be easily acquired. This paring-down process — pretty much ongoing, now that downloadable content is a priority — can take several months.

Step 2: Licensing
Send in the lawyers! The artists’ representation is contacted to discuss permission and fees for a song’s use. “We don’t get everything we ask for,” Eric tells us matter-of-factly. “Some artists are just not interested, for whatever reason.” Some change their minds after seeing private game demos from Harmonix (see sidebar); other times, just having a powerful partner like MTV can help open otherwise stubbornly closed doors. “They brought a lot of firepower — and so far,” Eric says with a laugh, “they haven’t goobered us up too much.”

Getting legal permission can take anywhere from weeks to months, and “we were still getting licenses three weeks before we finished the game,” Eric reveals. Even when the licenses come through, Harmonix looks at the list to make sure it’s balanced among different artists, genres, and eras of rock ‘n roll.

Step 3: Remixing
With a deal in hand, Eric works with an engineer from the record label who has access to the multi-track master tapes or digital recording sessions. That is, assuming they still exist. “In some cases, a song is approved but nobody can find where the tape is,” explains Eric. “Or you get stories like ‘Oh, the tape was on a train that crashed into some other train, and blew up and the tape’s gone and no one knows where it is’ — and then you find out it’s actually at the old ex-manager’s house. The labels do a lot of detective work for us.” Other times the original tracks are unusable because multiple instruments have been combined into one track — a very common occurrence in the late ’50s and early ’60s, as studio engineers tried to capture ambitious ideas on limited equipment. (Even the Beatles’ magnum opus, Sgt. Pepper, was created with a humble four-track recorder.)

Assuming the masters can in fact be used, they’re custom-remixed for Eric’s unique needs and digitized as a ProTools session. From here on, it’s all Harmonix.

Step 4: Implementing
“Once it gets here, we do a little bit of dressing up,” says Eric, which includes, say, mixing multiple guitar parts down to just what the game will use. And though Rock Band has only four player positions, you might still be hearing seven to 10 discrete tracks of audio, which are then combined into just one track for efficient disc-streaming.

Now it’s a matter of mapping out the notes. For Expert difficulty, “we try as much as we can to do a note-for-note transcription,” Eric reports. “The drums aren’t that subjective — there’s not that much interpretation. There’s more with the guitar and bass because we’re trying to crunch 22 frets into five. We spend a lot of time [making sure] the way we reduce it to five frets feels like playing the guitar.”

For the parts below Expert, notes are simply removed, and the “important” ones are retained. Eric says playing drums is “more about the independence of your limbs,” so the easier paths let you move, say, your right foot and right arm in sync instead of making them work independently. The final playing patterns go through several iterations based on the order of the presentation, so earlier Easy songs are simpler than the later Easy songs. The game constantly tries to train you for the next-highest skill level, but try more than one career and you’ll quickly discover that the songs are in different orders for different solo instrument campaigns.

The completed note maps are encoded as MIDI data; Rock Band then runs that data in sync with the music. That MIDI file also triggers lighting changes, camera angles, and animations, such as the singer’s stage-dive at the final chorus of “Learn to Fly.” Artists create those elements, but since the audio team knows the songs measure by measure, they program the MIDI file to tell the game what to show and when. Eric also points out that the game pulls from a pool of animations, so you won’t always see the same shot of the bassist every time.

From there, a song is tested by the QA team and either burned to disc or prepped for release as downloadable content. By the time it hits your Xbox 360, it’s been the work of several people over several months.