Head of Xbox, Phil Spencer, wanted to shed some light about backwards compatibility for Xbox 360 games played on the Xbox One. He went to speak on Giant Bomb’s E3 Day One podcast and he had lots to say about how the 360 games will play from a technical standpoint. What Spencer said is below.

“Millions of people made investments in 360 content,” he said. “We thought the right thing to do was to make that content go forward, but we didn’t know how difficult it would be. Emulation is hard!”

“The approach that we’ve taken is to actually emulate the full Xbox 360 hardware layer. So the operating system for the 360 is actually running when you run the game,” Spencer explained.

“If you watch the game’s boot you’ll see the Xbox 360 boot animation come up. From a performance standpoint it allows emulation to work. We’re able to get frame by frame performance equivalents.”

“Xbox Live thinks you’re on a 360, so people have been asking ‘hey, why are you playing Mass Effect on the 360?,’ I was actually playing on the Xbox One.”

Normal Xbox One features such as streaming and screens hotting are still available since the Xbox One thinks you are playing a normal game.

“The 360 games think they’re running on the 360 OS, which they are. And the 360 OS thinks its running on the hardware, which it’s not, it’s running on an emulated VM. On the other side, the Xbox One thinks it’s a game. That’s why things like streaming, game DVR, and screenshots all work, because it thinks there’s just one big game called 360.”

Spencer went on to explain exactly how the emulation process works.

“You download a kind of manifest of wrapper for the 360 game, so we can say ‘hey, this is actually Banjo, or this is Mass Effect. The emulator runs exactly the same for all the games.

“I was around when we did the original Xbox backwards compatibility for Xbox 360 where we had a shim for every game and it just didn’t scale very well. This is actually the same emulator running for all of the games. Different games do different things, as we’re rolling them out we’ll say ‘oh maybe we have to tweak the emulator.’ But in the end, the emulator is emulating the 360, so it’s for everybody.”

Phil said that the games are not going to be altered from their original 360 form at all.

“The bits are not touched,” he said. “There’s some caveats, and as always I like to be as transparent as I can be on this: Kinect games won’t work from the 360, because translating between the Kinect sensors is almost impossible.”

An issue Spencer address that engineers were having trouble with are multi-disc games.

“We’re still working on multi-disc,” he said. “Lost Odyssey and Blue Dragon are some of my favourites from the 360. There’s actually work in packing a multi-disc into single that requires us to go back and look at the original package on the multiple discs and reconfigure that.”

Microsoft announced the backwards compatibility feature at their E3 press conference, which has already been a great marketing strategy to sell their console. The feature will be available for Xbox One Holiday 2015.

Source: Gamespot

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