CUBASE NOTES

Tempo-independent Loops

Published in SOS September 2002
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Technique : Cubase Notes

Cubase has always had good facilities for creating tempo-independent loops, and this month we take a look at how Cubase SX makes this procedure even more accessible.

Working with audio loops has to be one of the most common techniques musicians embrace when producing music with Cubase, so it's no coincidence that one of the most common questions asked by users is "how do I change the tempo of my loop to fit the project?" Aside from time-stretching, the usually less-than-satisfactory mathematical process of changing the tempo of a loop without altering the pitch, the best way to change the tempo of drum or single-line instrument loops is by using an application like Recycle.

However, as many long-time users will be aware, Cubase has always had Recycle-like abilities for slicing a loop into its component pieces so they can effectively be played back at any tempo. Indeed, we covered VST's popular 'Get M Points, Snip At M Points' approach in April 2002's Cubase Notes. But the process of working with hitpoints for audio has been improved for the better in Cubase SX, and that's what we're going to be looking at this month.

So you've imported an audio loop onto the Project window and encountered the inevitable stumbling block: either you want to change the tempo of the project to match the unknown tempo of the loop, or you want to change the tempo of the loop to match the existing tempo of the project. What do you do?

Figure one: The display of Cubase's Hitpoint Mode will look quite familiar to users of Recycle.

First, select the audio event containing the loop on the Project window and press P on your computer's keyboard. This is a handy shortcut for setting the positions of the left and right locators to the start and end points of the current selection, which in this case is the loop. Next, double-click the audio event to open it in the Sample Editor.

Cubase needs to calculate where the beats fall in the loop in order to generate a series of audio hitpoints. To do this, activate Hitpoint Mode by clicking the Hitpoint Mode button on the Sample Editor's toolbar – this is the last button to the right of the toolbar, next to the Selection pop-up menus. After a short moment, the hitpoints should appear, as shown in figure one.

When Hitpoint Mode is active, you'll notice that the right side of the Sample Editor's toolbar displays a whole new set of parameters. By entering the length of the loop in bars and beats and specifying the time signature, Cubase will be able to calculate the tempo of the loop, which is shown by the parameter labelled Original Tempo.

At this point, you could just set the tempo of the project to the tempo of the loop, although you'll have to do this manually since there's no 'tempo to project' function at the moment. Admittedly, though, that's just wishful thinking from a lazy computer musician.

However, if you don't want to change the tempo of your Project, the alternative is to change the tempo of the loop, which requires a few more commands.

Cubase SX provides a versatile collection of facilities that enable you to fine-tune the locations of hitpoints to perfection. This is important because the final step in making a loop tempo-independent is to divide it up into a series of slices, based on the positions of the hitpoints. The general rule of thumb for hitpoints is to have one hitpoint per beat so that, ideally, there's effectively one beat in every slice.

You might have noticed another addition to the Sample Editor's toolbar when Hitpoint Mode is active: the Hitpoint Sensitivity slider. As its name suggests, this slider sets how sensitive Cubase's hitpoint-detection algorithm is, enabling you to decrease or increase the number of hitpoints in the loop by dragging the Hitpoint Sensitivity slider left or right respectively.

When you have a loop open in the Sample Editor, it's very easy to spot where the beats are and whether all the necessary hitpoints have been created – there should be a hitpoint for every beat of the loop, just like the example in figure one. You'll probably find the default setting perfectly adequate nine times out of ten, but occasionally the Hitpoint Sensitivity slider can come in useful if not every beat has been detected, or if too many superfluous hitpoints have been added where there are clearly no distinct beats.

Useful as the Hitpoint Sensitivity slider can be, occasionally it just doesn't seem to be able to get the right balance between essential and superfluous beats. If you want to remove certain hitpoints, and the Hitpoint Sensitivity slider removes more than just the hitpoints you don't want to keep, the Hitpoint Edit tool (available in the selection of tools on the Sample Editor's toolbar) can be very useful.

The Create Audio Slices command chops an audio event into smaller audio events and creates an audio part to hold them.

Clicking a the triangular part of a hitpoint with the Hitpoint Edit tool selected effectively 'mutes' that hitpoint, which is why your mouse pointer takes on the shape of the Mute tool you'll recognise from the Project window. If you do this, notice how the triangle greys out a little, but stays at the top of the display – you can click this again with the Hitpoint Edit tool to reinstate a hitpoint.

It's also possible to 'lock' hitpoints so they don't disappear when you drag the Hitpoint Sensitivity slider. With the Hitpoint Edit tool selected, click it again to choose the Hitpoint Lock tool from the pop-up menu. Now, by clicking the triangular part of a hitpoint again, you can 'lock' it, and notice how a small padlock is displayed by the triangle to indicate a particular hitpoint is indeed locked. And, as you'd expect, clicking a locked hitpoint with the Hitpoint Lock tool reverses the procedure.

You can further configure the way Cubase automatically creates hitpoints with the Use pop-up menu on the Sample Editor's toolbar, which by default is set to Sensitivity. Rather than creating hitpoints by detecting beats, you can create a set of hitpoints based on quantise positions by setting Use to quarter, eighth, sixteenth or thirty-second notes. And when Hitpoint Mode is active, you can even use the Sample Editor's pencil tool to create hitpoints manually.

After you're happy with the number of hitpoints, you can tweak their positions by dragging the triangular part of a hitpoint with either the Range Selection or Hitpoint Move tools – the latter is available by selecting the Hitpoint tool, clicking it again and choosing Move from the pop-up menu. To check you have the hitpoints in the right place, ensuring that each slice contains just one beat, you can click anywhere between two hitpoints with the Play (speaker) tool to audition that slice.

Finally, the bit you've all been waiting for: after the positions of the hitpoints have been tuned to perfection, select "Audio / Hitpoints / Create Audio Slices".

If you're using Cubase SX 1.02, you could now be scratching your head since the loop might appear to have vanished from the Project window. Don't worry, however, you haven't done anything wrong – this is an annoying bug that seems to have crept into version 1.02, though fortunately there's an easy solution.

When you select Create Audio Slices, what should happen is that the audio event is split into a collection of audio events, which are stored in a newly created part. Although this is exactly what happens in 1.02, the length of the audio part unfortunately gets set to zero. In order to resize it, first make sure there are no other events or parts on the track that should contain the full loop and right-click on this track in the track list, choosing Select All Events from the pop-up menu.

On the Event Info Line, notice the Length parameter and change it from 0.0.0.0 to the actual length of the audio loop. With a one-bar loop, you'd need to change the Length parameter to 1.0.0.0, for example. And that's it! The loop should now play back at the project's tempo, and if you change the tempo of the Project, the loop should always play in time.

Sadly, that's all we have space for this month. Next time, we'll be looking at how to make your sliced-up audio loops play back a little smoother at tempos that are significantly slower or faster than the original speed, plus some of the other interesting things you can do with hitpoints once you've created them.

Cubase News     There's been plenty of interesting Cubase news in the last month, including Steinberg's announcement that the much-anticipated Mac OS X version of Cubase SX will be released at the beginning of the forth quarter this year. While the vague timeframe has disappointed some users, it's still good to know that there'll be one less reason to boot into OS 9 by the fall. Since the review of Cubase SX 1.01 in the last issue, Steinberg have released a minor update to version 1.02. Most significantly, a second Track Mixer has been implemented (a surprisingly popular request) and mixer view presets make a welcome return, allowing you to easily store and recall popular mixer configurations. Cubase SX running on Mac OS X: notice the OS X-compatible Virtual Guitarist VST plug-in also being used with the application. After many 'less than legal' versions of Cubase SX finding their way onto the Internet that could run under Windows 98, Steinberg have responded to the criticism from some users and the full 1.02 installer will allow you to install and run SX on Windows 98. However, this doesn't mean that Steinberg have reversed their decision to support Cubase on the Windows 98 platform. Cubase developer Dave Nicholson posted a full explanation of the situation on a dedicated forum at www.cubase.net, but the bottom line is that while SX appears to run on Windows 98, it wasn't developed with this in mind and no testing has been undertaken. Still, with a demo version now in the pipeline, it's understandable that Steinberg want people to have the opportunity to try SX, so letting prospective users run Cubase SX without needing to upgrade their operating system first seems like a good idea. If you want to try installing SX on a Windows 98 machine and you don't have a 1.02 CD, you'll need to contact your Steinberg distributor (Arbiter in the UK, for example) for a replacement CD – a 1.00 or 1.01 CD with the update installers will not work. There will apparently be a small charge to cover postage and packaging. In addition to Cubase SX, Steinberg have now released Cubase SL, a junior version offering the core advantages of SX at a lower price point. Compared to SX, SL doesn't have the extended mixer views (although you can still mix from the Project window), surround sound support, the audio analysis functions, TrueTape, the SPL DeEsser, or the professional score layout abilities. You can only write automation with the Touch Fader mode, and the Offline Process History only works for built-in audio processes, not plug-ins. A full list of the differences between SX and SL is available at www.steinberg.net. While this is admittedly a very negative way to present the feature list, SL still looks like a great product and retains 'cherries on top' like the A1 synth, Quadrafuzz and Apogee's UV22 (but not the 'high resolution' version included in SX). Cubase SL is available now and upgrades from Cubase VST are priced at £129.99 (or £69.99 if you purchased your copy after the 1st March this year).