Ableton Live is a Digital Audio Workstation (DAW) that can be used for music production. I've been using it for a couple of years to create DJ mixes and remix other artists songs (also using another DAW called Reason). I got into Ableton when version 5 was released, as this added lots of features useful for DJs. The most significant feature introduced was 'warping', otherwise known as time stretching, which allows you to change the tempo of a piece of audio without changing the pitch. This is something of a departure from DJing on turntables, where you explicitly have a "pitch" control that true to form changes both the tempo and pitch of the record. Ableton's warping feature gives you creative freedom to modify both tempo and pitch, meaning that you can make use of songs that would be impossible on turntables because they're either too fast/slow and also create in key mixes. For DJs, Ableton also makes looping, restructuring songs and adding a whole wealth of effects very quick and easy, and also removes the hardware limit of turntables meaning that you can play as many songs as you can imagine all at the same time. Ableton is in fact so good, that when version 7 was released, I bought the full Suite edition and came to own my first ever piece of boxed, retail software.
The warping algorithm used in Live since version 5 has been Elastique Audio Efficient, and although this is an amazing piece of software that gives high quality audio results, one of the complaints about upgrades to Live is that they haven't included the Elastique Audio Pro algorithm. Ableton have obviously listened to their critics as one of the key features of the upcoming version 8 release is that they've included the Pro algorithm. The main difference in the Pro algorithm is that it preserves formants, I'd love to tell you why that's a good thing, but that Wikipedia article confused me.
I've been playing around with the Beta a little bit, and I thought I'd do a comparison between the old "Complex" (Efficient) warp mode and the new "Complex Pro" (Pro) warp mode. To do this I've used a snippet of Scott Matthew's Elusive played at normal speed, double speed, and half speed. This is a fairly extreme scenario, so the results are hopefully interesting. Below you'll find three audio files rendered from the same arrangement, one using Complex, one using Complex Pro and for the nerds one with Complex on the left channel and Complex Pro on the right channel.
The results aren't quite as marked as I was perhaps expecting, but the difference is certainly there and Pro appears yeilds better audio with less artifacts when altering pitch wildly. I had thought it would be worth the upgrade price alone, but having experimented, I'm not so sure. We'll see once the pricing is announced.