FEEL-GOOD FACTOR

Giving Your MIDI Tracks A Live Feel: Part 2

Published in SOS August 2001
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Technique : Sequencing & MIDI Controllers

Simon Millward demonstrates how to use the tools for extracting groove templates from audio recordings within most MIDI + Audio sequencers and offers his tips and techniques for using them to achieve more feel in your tracks.

Last month I explored the basics of improving the live feel of your MIDI tracks using the various groove manipulation tools available, with reference to the real-world example of James Brown's classic song 'I Got You (I Feel Good)'. As I've already demonstrated, there are many ways in which to create your own grooves. However, there are times when it is much more useful to fit the groove of your MIDI parts around that of an existing audio recording — for example, if you're building a track around a sampled loop. In such cases, you need to extract a groove template of some sort from the audio recording.

Though many hardware units now offer simple groove manipulation tools, dedicated facilities for extracting groove templates from audio are currently the preserve of software systems. However, these systems can be tricky to get the best out of, so I'm going to walk you through the process of generating a groove template from a loop of James Brown's 'I Feel Good' within Steinberg's Cubase VST in order to show you not only how to go about the process in general, but also to demonstrate the extent of VST's capabilities in this area for those of you unfamiliar with this sequencer.

Here are a number of MIDI file groove templates which Simon Millward generated from James Brown's 'I Got You (I Feel Good)' for this article: • rawfeelgood.mid is the groove as initially extracted. • feelgoodlazy8.mid is a more general-purpose version of rawfeelgood.mid. • feelgoodtight8.mid has been quantised to make its effects more subtle. • feelgoodgroove16.mid is a more general-purpose version of rawfeelgood.mid, and has also been adapted for processing 16th-note material. • feelgoodshuffle8.mid shows how the 'I Feel Good' groove can be adapted for a shuffle feel.

For information on other software packages which offer groove extraction, take a glance at the boxes throughout this article.

The first thing you need to decide is which bit of audio you're going to use for the groove-extraction process. If you're wanting to match your MIDI programming to a sampled loop then this choice won't tax the grey cells, but if you're wanting to impart the groove of a well-known song to your own track then it's worth taking some time to consider which bits of the source material are likely to be most useful. Ask yourself which sections have a particularly pleasing groove, bearing in mind that live musicians sometimes get more settled into a groove the further they get into a track — as we found, in fact, when looking at the tempo changes of 'I Feel Good' last month.

You may find that there are a number of equally pleasing sections of the groove, in which case you should try to whittle down your list of sections in terms of the practicalities of extracting groove information from them. In which of the sections is the definition of the rhythmic instruments particularly clear? If attack transients aren't well defined, of if players aren't tight enough with each other, this can confuse the groove extraction algorithm as to where each beat and division of the audio is meant to be. Another thing to consider is how much the tempo is fluctuating through your chosen sections — if it changes too much, this could make the resulting extracted groove unconvincing.

If you find that you still have several sections of audio which are both satisfying and clearly defined, then it's worth using a number of them for generating groove templates. As I made clear last month, the key to a successful live feel is a constantly changing groove, and this can be achieved quite easily if you have a number of similar groove templates which you can alternate and combine. Finally, on a practical note, it is a good idea to copy the segments of audio you have chosen to separate audio files, allowing a little extra audio on either side of each to keep your options open for the next stage of the extraction process.

Taking the first of your audio sections, the first thing to do when extracting a groove is to trim the boundaries of the audio so that it loops correctly. Doing this allows you to use the automatic tempo-matching function within many sequencers to superimpose your song's regular metric grid correctly on the audio. In Cubase VST, you do this from the non-destructive Audio editor.

First set up by eye an approximate playback loop and then, with the loop playing, tweak it until you get the best-sounding result. Obviously, you needn't pay any attention to any current bar and beat positions given in the editor window at this point, as these will be unrelated to the positions of the bars and beats in the audio at present. It may also help to switch off any snap-to-grid function in order to get the required editing resolution.

Don't be afraid to spend a bit of time getting the loop exactly right, as the precision of the loop is extremely important. Innaccuracies here will result in subtle innaccuracies in the eventual groove, and we have already seen last month how important subtleties are to a great groove. It is also vital to establish a good downbeat at the start of the loop, to make sure that your groove is not 'out of phase' with the sequencer's metric grid later. When you are satisfied that the loop is as good as you can get it, make sure the audio is highlighted and trim the section at the loop start and end points, deleting the unwanted audio outside these points. In Cubase, you can use the Snip Loop option within the Audio editor's Do menu.

Next, you mark a time period corresponding to the number of bars you wish the newly trimmed audio segment to fill once tempo-matching is complete. Often, the sequencer's loop markers are used for this. In Cubase you select Fit Event To Loop Range in the Do menu, which brings up a dialogue box where you can choose to change the tempo of the Song to fit its metric grid correctly over the audio. Once the tempo has been changed, double-check that the tempo is matched by playing back the audio against the sequencer's internal click.

It is now time to establish where the main beats and their divisions occur in the audio material. These are usually the most strongly accented points in the audio waveform, and are referred to as Match Points in Cubase. They can be found automatically using the Get M-points option in the Audio editor's Do menu. The dialogue this leads to includes settings for Sensitivity and Attack, which regulate how the analysis software finds the Match Points — when the process is done, you are able to view the Match Points under the audio waveform. Some experimentation is required to find the best settings for the particular audio being processed, and you should aim to get at least one point every eighth or sixteenth note, depending on the smallest beat division in the audio. Even when you've experimented with the settings, you may still find you're not getting the correct number of Match Points, in which case you may need to add or delete some of them manually, which Cubase lets you do with its pencil tool.

Bear in mind that each of Cubase's Match Points has a velocity value, indicated vertically, and that this velocity setting can be used to create a more natural groove. Consider tweaking the velocity values if comparatively unstressed beats have high velocity values assigned to them, or if accented beats aren't registering a high velocity setting.

Once you are satisfied with the number, placement and velocity of the Match Points, it's time to extract the groove from them. Open the Match Audio & Tempo editor from the Do menu. The audio waveform and Match Points are shown in the lower half of the display. In this window's Audio menu is the M-Points To Groove option. This extracts the groove and saves it in the default grooves folder, whereupon it is immediately available within the Cubase Groove Control window. This raw groove will often only be usable on selected material, as was the case with my initially extracted groove. After all, as we gleaned from our analysis of the James Brown track last month, grooves tend to be intricately connected to the actual parts within a track's arrangement. However, you can create a more generally usable template by toning down a little of the raw groove's individuality.

To begin with, it can help to manually adjust any notes which are particularly 'out of time' to bring them just a little more into line with the metric grid — it is the most extreme timing variations which most tie a groove to a specific track. However, be careful not to overdo this, or you could upset the flow of the groove as a whole. Once this has been done, you can make the groove even more general-purpose by applying a subtle iterative quantise — I suggest no more than a 25 percent strength to start with — to slightly tighten up the feel.

If the track you've analysed is based around eighth-note divisions, and you want to apply it to parts with 16ths, then you're going to have to generate suitable new quantisation points in between the existing ones. Cubase allows you to do this easily, because it lets you open up your groove templates in a piano roll-style editor from a button in the Groove Control window. What I do is duplicate the main eighth notes of the groove, drag them all a 16th note later, and then iteratively quantise them to be locked a little more tightly to the beat.

It can be worth saving a number of different versions of your new groove, in which the 16th notes get successively tighter. Not only does this allow you to experiment to find the most applicable groove for a given part, but it also allows you to make a part's timing tighter as the track progresses — a phenomenon which we saw demonstrated in 'I Feel Good'. Another thing to consider is dipping the velocity values associated with 16th-note quantise points, in order to make them lighter and more natural-sounding. As a matter of habit, try to remember to name your grooves according their resolution and character. Therefore the raw 'I Feel Good' groove could be named 'feelgoodraw8', while the 16th-note groove might be labelled 'feelgoodraw16'.

You ought now to have a range of natural-sounding grooves which will be good for humanising a wide range of material. However, there is more mileage to be got out of our extracted groove yet! The first way you can adapt this groove for different uses is to push the main quarter-note down beats slightly early, while delaying all the up beats a little. This produces a very subtle shuffle feel which can help enliven uninteresting drum programming. It is best applied to the hi-hat and snare and tends to make the rhythm sound tighter and snappier.

information     A variety of groove templates generated from 'I Feel Good' are available on the SOS web site, at the following URL: www.soundonsound.com/sos/aug01/articles/groove2.asp For more information on the software mentioned in this article, check out the following web sites: www.cakewalk.com www.digidesign.com www.emagic.de www.markoftheunicorn.com www.propellerheads.se www.steinberg.net

If your groove covers a number of bars, another nice trick is to push the groove's main beats a little early towards its beginning and end, while delaying them a little towards its middle. This cyclic pattern can work well, especially when applied selectively. Using it on just your bass drum and hi-hat parts, for example, can produce pleasant flamming effects between them and the snare. The amount of push and delay you need to use will vary depending on the material to processed — obviously, a tight feel will only be able to cope with a little such tweaking before starting to sound messy.

Another fertile place for experimentation is in the field of velocity and duration. If your sequencer allows you to program these into the groove, then take the time to try it out, as this can make a great deal of difference to the feel. While Cubase and other sequencers do tend to be pretty good at extracting natural velocity characteristics, you still shouldn't necessarily take it for granted that the extracted velocity settings are the best for your track. If an extracted groove feels lumpy then it may well require attention in this area.

The first thing to realise is that velocity and duration are both responsible for accentuation. Heavily accented notes will usually tend to have a longer duration, for example, and short notes which require accentuation will need especially high velocity values to compensate for their brevity. Manipulating velocity values is a common practice in drum programming when creating variety and realism, and many hardware and software sequencers make this easy to do. However, because considerations of note length are often considered irrelevant when processing drums, it is tempting also to forget about duration when processing more melodic material. This is a shame, as many instrumental grooves are heavily dependent on duration characteristics — take staccato slap bass, for example. And even drums can benefit from subtle duration tweaking, so don't completely reject it out of hand.

A few experiments are worth doing and could produce exactly the effect you're looking for. Try the simple technique of accenting every other 16th note within a groove or, alternatively, try something more unusual, such as accenting the second of every three 1/16th notes to give a kind of continuous off-the-beat feel. Another angle to try is to increase the difference between the accented and unaccented notes in your groove — this usually only requires a single MIDI process and can make MIDI parts more lively and natural. Other options include randomisation of velocities and durations, or the use of undulating patterns of these values.

Most readers will already be familiar with how to apply standard quantise functions within their chosen sequencer, and the use of groove templates is often very similar. In Cubase VST, the groove templates you create are available in the Groove Control window, alongside any other grooves you may have in the default grooves folder on the hard disk. From this window you can apply the groove's timing, velocity and duration scaling to any MIDI part in varying degrees, depending on the positions of three sliders. An invaluable element of this is that you get a chance to regulate and test the groove processing in real time before you apply it, and this is something which is excellent for experimentation. Other sequencers are even more flexible, carrying out all their groove processing in real time, which allows even easier tweaking.

I would recommend hard-quantised bass-drum, snare and hi-hat parts for the initial testing of any grooves you extract. A four-on-the-floor bass drum with a standard snare on the second and fourth beats of the bar is a good starting point, with hi-hats at eighth or 16th-note intervals. This allows clearly defined comparisons to be made between straight and grooved versions. It may also be appropriate to test the grooves on other drum and percussion parts you find yourself using frequently. The more characteristic the groove, the fewer types of material it's likely to work with. On the other hand, if you can find which type of part a particular groove does work with, then the pay off can be well worth the effort of finding it.

It is important to remember that the effects of groove quantising are often subtle enough that they can only be picked out consciously by very careful listening. The process of creating and testing grooves requires patience and the willingness to spend time developing an instinct for which kinds of combinations and relationships of groove templates work best. This means doing lots of comparisons and lots of trial-and-error processing. However, with a little practice, the results can be magical.

The difference between monotonously programmed machine music and subtle performance is like the difference between painting by numbers and great works of art. Fortunately, music software is now beginning to become advanced enough to digitally approach our human analogue reality. Functions such as groove quantising are the cutting edge, which is why the creation and use of groove templates can be so exciting, and why they can teach us so much about what makes musical performances special.

Simon Millward is the author of the successful Fast Guide To Cubase VST book, now in its third edition and available through SOS Mail Order at www.soundonsound.com/shop

Successful Groove Extraction: Key Factors     Groove extraction from audio can be a delicate process, but if you keep the following key factors in mind, you ought to be able to get good results most of the time: • Choose the target audio segment carefully, making sure that its rhythmic elements are clearly defined. • Make sure that the chosen section is edited to begin precisely on the down beat of the first bar, and that it is the correct length so that it loops smoothly and in time. • Take time to experiment with the settings for the groove extraction algorithm in your chosen MIDI + Audio sequencer, and aim to get at least one quantise point per division of the beat. • Manually edit the groove data after extraction to delete any unwanted quantisation points, and correct any errors. • If you need more beat divisions in the groove data, generate them from the existing data using a copy procedure, and consider further quantising them if necessary. • Experiment with editing your groove data in different ways, and create several variations of the same groove to allow for flexibility in use. • For a general-purpose template, consider applying a mild iterative quantise to the groove data, to even it out slightly. • Test your groove template on target MIDI parts to make sure that it produces the desired results. Remember that the groove can be applied selectively to different parts of the arrangement — each groove template will not necessarily work well with all types of material. • Name your groove template meaningfully, according to its resolution and purpose. This makes it easier to use at a later date when you may have forgotten where it came from.