For those about to rock, please read the following instructions
If Rock Band 4 is your first entry into the recently revived rhythm game franchise, congratulations! Not only are you in for a hell of a party, but you've officially got the easiest set-up out of everyone: Simply buy the Band-in-a-box bundle, insert the disc, maybe download a few extra tunes from the store, and you're all set. For those returning to Rock Band with their old instruments and downloaded tracks, it's a completely different story.
Rock Band 4 makes a vast effort to let you use almost every single song or plastic instrument you've ever bought over the years, and while it's commendable what Harmonix has done to cater to a wide variety of returning customers, the sheer number of configurations makes things a bit complicated. And in order to consolidate things under the Rock Band 4 'platform' and bring them to Xbox One and PS4, some things had to be left by the wayside. If you're wondering what made the leap forward, what you'll have to re-buy, and what didn't make the cut, read on.
Most of this information was provided courtesy of the Harmonix Rock Band forums and the official Rock Band Twitter account.
The Rock Band Music Store
Generally, if you bought a song on the store as DLC, it'll make its way over to Rock Band 4, and you'll be able to redownload it for free. Harmonix has added hundreds of songs to the store pre-launch, and will continue to add more over the coming weeks. So if your favorite song on the Xbox 360 hasn't shown up yet, give it some time. It'll most likely be there soon.
Also, if a song on the store is asking you to pay money, but you know you've purchased it before, don't buy it again. Harmonix is still working out some kinks, and a few track packs haven't had their licenses transferred over yet (like the special Doors pack or the Rock Band 3 pre-order bundle). These songs will be made available to you eventually, so be patient - 1700+ songs is a lot to go through, and there are going to be a few hiccups until everything's running smoothly.
Perhaps the most important thing to remember in all of this is that licenses only transfer between console families. Xbox 360 licenses will only transfer to Xbox One, and PS3 licenses will only transfer to PS4. So if you bought all your Rock Band DLC on and Xbox 360, and you currently own a PS4, those tracks will not transfer over, and you'll either have to rebuy them all on your PS4 or pick up an Xbox One (which, ironically, might actually be cheaper for some people). Sorry Wii Rock Banders - since there's no Wii U version of Rock Band 4, and no way to transfer those licenses to either Xbox One or PS4, you're out of luck.
Rock Band Network
In addition to the main offering of DLC tracks that Harmonix themselves licensed and released, there was also a massive library of independently-created and published tracks made available in the Rock Band Network. RBN features over 2000 tracks from a wide variety of indie and major artists, from all corners of the globe - and as of launch, none of these tracks are making their way into Rock Band 4.
The issue stems from the XNA framework these tracks used when RBN was active. XNA was a programming language created by Microsoft specifically to enable easy game creation on PC and Xbox 360. Once Microsoft stopped supporting XNA, RBN all but shut down. And since neither the PS4 or Xbox One support this framework, porting these tracks over means recharting all of them specifically for Rock Band 4 - which opens up a whole new can of licensing worms.
There's no official word on whether any of these songs will get brought back to Rock Band 4 through official means, let alone whether you'll be able to download them for free if you purchased them in the past. If support for any of these tracks comes to Rock Band 4, it'll be after launch.
Exported songs
If you've exported tracks from any of the Rock Band games that let you do so, their songs will be available to play in Rock Band 4 after launch. Games that will allow you to import their songs into Rock Band include:
-Rock Band
-Rock Band 2
-Lego Rock Band
-Green Day Rock Band
-Rock Band Blitz
If you haven't imported these tracks yet, you're probably out of luck. While you can currently export tracks from Rock Band (by paying a nominal fee) and Rock Band Blitz (by simply buying the game), Rock Band 2, Lego Rock Band, and Green Day Rock Band's export keys have expired, though a few of the songs from these games have been made available on the Rock Band Music Store.
Rock Band games that cannot currently be exported include:
-Beatles: Rock Band
-Rock Band 3
There are plans to allow players to export Rock Band 3's set list, though nothing concrete about how it will happen has been announced. If it comes, it'll be after launch - and hopefully soon, as Rock Band 3's set list was killer.
Oh, and remember: certain songs from individual entries that wouldn't export due to licensing issues still won't be available in Rock Band 4.
Track Packs
Track packs are disc-based stand-alone expansions that provide fans with various bundles based on different musical genres. Track packs like the AC/DC Live Album or anything with the "Track Pack" label on the case can also be exported as well, and since the songs from these discs are also featured in the Store, their export codes still work (well, all of the songs are in the store except the AC/DC Live Album because the band has this weird rule about not selling singles so the only way to get it is by buying the disc and dear God why is this so confusing). As long as the code hasn't been used before, they should still be valid, and if you can find a good deal on them, it's a good way to beef up your library.
Update: According to a list provided by reddit user Easy_Fan, the AC/DC Live Track Pack isn't available yet in the Rock Band 4 Music Store, but it should be when the rest of the exportable tracks make their way up.
Delisted tracks
Sometimes, Harmonix loses the rights to certain songs. It happens for a variety of reasons, but ultimately, it means that once it's delisted, you're no longer able to purchase that particular track. If you bought it before it was delisted, you should still have access to it in Rock Band 4, even if it's been removed from the Store. And remember, if the song hasn't shown up in your library yet, give it some time before you go complaining to Harmonix.
Instrument compatibility
Here's where things get really confusing. Click here if you'd like to look at a very convoluted chart about what gear will and won't work in Rock Band 4, but the gist is this: most wired Rock Band controllers will work on PS4, but not on Xbox One. If you've got wireless PS3 controllers, they should work just fine on the PS4, since they just use Bluetooth signals. Wireless Xbox 360 controllers, however, require a special legacy adapter to read the signal, which you can buy separately at many fine retailers for $24.99. The Legacy adapter is also included with the disc-only version of Rock Band 4, but it increases the price by $20.
Other things to note: The Rock Band 3 Keyboard is not compatible with Rock Band 4, as none of the songs have had their keyboard notes charted (I know, it really sucks). The Rock Band 3 Pro Guitar is currently in testing, but not supported. Guitar Hero 2 controllers are currently in testing as well. Singstar and Lips microphones are not supported. That hugely expensive ION Drum Kit? Compatible on PS4, not on Xbox One (it's wired). Rock Band 4 includes support for the cymbal add-on for the drums, but not for the stage kit (aka home-grade fog machine and strobe light), though support for the latter might be coming post-launch.
