This week we’ve been taking a closer look at the REX file format which was originally developed by Swedish music software company Propellerheads. Most sample libraries released these days include REX among the formats on offer with Nine Volt Audio in particular designing their libraries first and foremost for REX/RMX users. We caught up with the company’s owner Kyle Z, to find out more about the format….
What is the REX format?
The REX format is a compressed audio format that allows timing and “slice” info to be saved within it. This info is then interpreted by the sequencer, sampler or REX file player, enabling the REX audio file to adapt to the tempo of the track. Creating REX files can only be done using Propellerhead’s ReCycle program.
In which software can REX files be used?
Just about every major (and minor) sequencer can play REX files natively – or includes a player that can use them. Beyond sequencers, many beat and loop oriented samplers can also play the format, including (but not limited to) Stylus RMX, Kontakt and of course several of the units within Propellerhead’s Reason program. If you don’t own a good REX player, the UVI Workstation is free and is very flexible.
Beyond the ability to adapt to a track’s tempo, the REX format has quite a few other helpful features. For example, with most REX players it is extremely easy to modify the loop to create something that sounds completely different from the original audio. If you need to change the pitch of three specific slices, reverse two, delete eight others, rearrange the order of all the slices and then add your own swing settings, you can do this in short order with a well sliced REX file.
Do you have any top tips for using REX files?
ReCycle features a “stretch” function that has been designed to fill-in-the-gaps between slices when you slow your loops down below its original recorded tempo. In practice, the quality of the “stretched” portion of the sound is highly dependent on the source material. Loops with lots of high frequency content will work better; like hi-hats. Loops with lots of sustained low frequencies, like bass guitar, don’t work well at all. So test out the “stretch-ability” in ReCycle before saving it to the REX format. By default, ReCycle has the stretch turned to 40%.
In many ways these formats are very similar, as they all rely on the file creator to add timing info and slices to the audio before saving it. However, the ability to manipulate, edit, and be creative at an individual slice level is generally much easier with a REX file.
Are there any disadvantages to using REX files?
The REX format works extremely well with percussion loops, but does not work quite as well with tonal material – but this is also true with most other “slice” formats (ACID wav and Apple Loops).
The other disadvantage is if the file creator does a poor job of slicing the file. If he or she puts a slice in the wrong place – or more typically, doesn’t put slices in all the places that they should go, all the cool functionality that the REX format is capable of can go out the window pretty quickly and can be rhythmically “off” if used at any tempo other than the original. If you’ve ever purchased a poorly made REX library it can be disappointing! If the REX file isn’t made perfectly, there’s not much use in having it!
But Nine Volt Audio came up with the “BPM Flex Series” to combat these disadvantages. Along with our drum and percussion libraries, we have many tonal REX libraries (guitar, bass & synth) that can be used at huge ranges of tempi while still sounding completely natural – and of course every loop is expertly sliced!