There are countless great rock songs in existence. How do you pick just 45 for a huge game like “Rock Band“?

Last week I visited Harmonix Music Systems, the developer of the upcoming music title (published by MTV Games), for a behind-the-scenes tour. There, I got to talk to the one man who deals with it all — Audio Director Eric Brosius.

Brosius began working at Harmonix several years ago, when the first “Guitar Hero” was in development. He was the Audio Lead on “Guitar Hero” and “Guitar Hero II” and is now the Audio Lead on “Rock Band.” His responsibilities include selecting songs, dealing with record labels and communicating with licensing people to acquire the songs.

While that sounds simple enough, Brosius elaborated on the laborious process of choosing the right songs for the game, including:

• How many thousands of songs were considered
• The specific criteria a song needs to make it into the game
• Deciding which staffers’ bands would make it into the game (”It wasn’t very much fun.”)

Here’s an excerpt, where Brosius talks about how in some songs it’s inevitable that certain band members will take the spotlight over others:

“Sometimes we find songs that one or two instruments are just great even if the other two aren’t the most interesting — that’s what part of what being in a band is. Sometimes you get to step forward and do your thing, and other times you’re just holding it together while other people in the band do their thing.”

Read on for the whole first part of the interview, conducted in the sound-proof jam room at Harmonix’s offices.

The process of choosing what songs go into the game was a long one. Although the tracklisting for “Rock Band” could have easily become a list of Brosius’s favorite tunes, he actually looked elsewhere for ideas. From scouring newsgroups and forums to asking the opinions of Harmonix employees, Brosius amassed a spreadsheet of over 3,000 songs. From there, he whittled the list down to 60 to 80 songs. Then he and a team of employees came up with an ideal wishlist with more than 45 tracks that the licensing people will go after. “We send them more than 45, because we know we’re not going to get everything we want, and there’s a lot of back and forth,” Brosius explained.

Whenever Harmonix received word that a few songs were cleared, staffers met up and decided which of the approved songs they actually wanted. A few might’ve been on their “A-list,” which were accepted right away, but if the others were on their “B-list,” the game-makers would wait to see if more of their top choices were confirmed. However, there was another thing to think about when approved tunes came in. “As we’re getting songs in, we start to worry about the balance of the game, whether we have enough songs from different genres,” Brosius said. “We’re constantly revising our song list. We want to have a mixture of songs that are big hits and stuff that’s a little bit more underground. We just try to mix it up a lot.”

A musician himself (Brosius was the guitarist for the ’90s alt-rock band Tribe), the audio director’s technical knowledge and musicianship also came into play when selecting the right songs for the game. It wasn’t always about picking a band’s biggest hit, especially for a game like “Rock Band” where there are four players’ parts to consider. “We look for songs that have great interactions between parts and good band moments,” Brosius said. “Or sometimes we find songs that one or two instruments are just great even if the other two aren’t the most interesting — that’s what part of what being in a band is. Sometimes you get to step forward and do your thing, and other times you’re just holding it together while other people in the band do their thing.”

Some bands and record labels have actively pursued the developer to get their songs into “Rock Band.” But the case was quite different when Harmonix was working on the first “Guitar Hero” several years ago. “When we first started trying to get songs for ["Guitar Hero"], one of our biggest problems was trying to convince bands and managers that this was going to be cool,” Brosius said. “Now if we fast-forward to ‘Rock Band,’ because of the success of the ['Guitar Hero' franchise], people get it now. For the most part, bands and labels are very excited to be a part of it.”

However, not every band could make it onto the game disc. “We do have a select number of slots, so we’re fairly selective about which songs are going to be on the disc,” Brosius said. And with more than half the company in their own bands, even some Harmonix staffers didn’t make the cut. Brosius had the unenviable task of helping to decide who made it in and who didn’t (along with CEO Alex Rigopulos and Vice President of Product Development and fellow ex-Tribe bandmate Greg LoPiccolo). “Basically, we had everyone submit songs that they wanted in the game, and we had this very painful process of really trying to pick the ones that we thought would work best. It wasn’t very much fun,” Brosius said with a heavy sigh. “I’m hoping it was reasonably fair. We listened to them all under the same criteria [as the other songs]. Do they play well? Are they appropriate? I think that there were some disappointments, but hopefully those bands will be able to have some downloadable content and people will be happy in the long run.”

Check back next week for Part Two of the interview, where Brosius sheds light on programming the songs into the game, crossing paths with the “Guitar Hero III” developers and the future of downloadable content for “Rock Band.”

[UPDATE: Part Two added on 11/5/07. Read it here.]