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Some General Notes about Midi Input, Output and Editing.
Basic Editing Suggestions
Common Guitar Editing Problems
Mimicking The Acoustic Guitar's Interior Reverberation
Using Notation Programs
Midi Input
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When I first started to put my studio together, a friend with quite a bit of experience gave me one piece of advice. That was "Insist on a good performance." I think it was great advice. Once you start saying we'll fix it in the mix you're heading down an endlessly long road that seldom results in a good recording (and never, a great one), and I think this is just as true when it comes to midi. If you have to spend a week fixing everything just to get the right notes, you're going to run out of gas long before you get around to the real work of making your midi track sound real.
This can be especially true of guitar tracks, and I've had conversations with several people where the consensus seemed to be that the guitar isn't a very useful midi input device. OK. The statement needs to be framed by some pretty stringent qualifiers. Midi Guitar recordings are often full of unwanted notes and other data, but if guitar is your main instrument and you're not a keyboard player, it becomes the only practical midi input option for a complex piece. Certainly it can be daunting to record your guitar part and find maybe hundreds of short notes you don't want, and then face the job of sorting through and erasing them all. You may very well find that every string touch has been recorded sometimes including a lot of information like erroneous bend data. Of course the reason these events are recorded is that something was detected that at the very least, had the properties of velocity, pitch, time and duration, but in the output of this data we find ourselves restricted to whatever sounds the soundfont or midi instrument has to offer. And if a fingered F is recorded as an E bent up a half step, then we have more problems than we want to deal with.
Many of these problems can be avoided by taking the time to get your pitch-to-midi converter set up properly, and in a way that suits the piece you want to record. Most of this redundant data is easily erased, and if it's CC (control change) data, like decay etc, it probably won't cause any problems if it disappears. Bend data requires special care, since it can result in misnamed notes. It's something that needs to be controlled at the source and there should be a setting on your converter that will control the limit of bend data which is recognized before the next higher note name is recorded. It's usually indicated in semitones. For a pop style solo, you'll probably want it set to at least 2 or even 12 as Paul White suggests in his review of the Roland GR-33 at www.soundonsound.com . But I find it gets a bit messy if you have a very smooth style and are playing a lot of chord work with bits of melody in between. In that case, I find it better to set the bend range to 0, and draw any bends in later in the Key Editor.
Note events that are very short, and sometimes of surprisingly silly pitches, may be generated by finger squeaks, touching a string near a location that would generate a strong natural harmonic (or just touching it at all), or your finger leaving a string. If you can set the sensitivity of your synth or converter lower, you can get rid of a lot of this aggravation, but if you set it low enough to remove all of these artifacts, you'll probably find that you are missing some data (notes) that you would like to have.
The trick here is to find a balance between too much editing and too few notes, or maybe having note values recorded with too short durations because the sensitivity threshold is set too high. Having a few extra note messages isn't always a bad thing if the soundfont provides a creative way to use them. After all, something happened to make that signal in the first place, and no matter how quiet or short the event was, it probably contributed in some way to the acoustic performance. So, rather than simply get rid of these events, wouldn't it make more sense to try to find something to do with them that might enhance the midi performance? In the tutorial about editing the Mixed Bag Demo, I use the Logical Editor in Cubase to place all the very short notes on a channel preset that played muted notes. You can then play with velocities and so on. If there's no way to use the event to good effect, you can always mute it or delete it. In a future version I intend to have a preset in the G1 fonts, that includes finger-squeaks.
There are lots of extraneous noises that come from the guitar, even when played by a very clean and accomplished player. It's the lack of these noises that strikes me as a good clue that we're listening to a midi recording rather than a live performance -that's assuming the rest of the sound is near flawless. You've probably noticed that many demos for guitar soundfonts demonstrate the instrument in a group setting. I chose to show it soloed in the Mixed Bag Demo, so you could hear just the font, and with a bass part in the Home Sweet Home demo to demonstrate how the excessive cleanliness seems to disappear in the company of another instrument - almost the same as how extraneous guitar noises disappear in a group setting.
All of these problems with Midi Guitar beg a question, which I am often asked: Why would a guitar player want an acoustic guitar soundfont?
Well, even though I have the original guitar used for these samples, sometimes it's easier to use the soundfont, particularly for a simple part on a scratch track as I did here. To use the sound font in this instance was just as effective and far easier and more flexible than stopping everything I was doing to set up and record myself to an audio file. It also gives you the opportunities to road test various guitars for a certain purpose, if you have a nice collection of sound fonts to choose from.
Even good players will benefit from using midi guitar tracks if they are working in a situation where they might later want to edit tempos or delete a beat somewhere in the piece to make it fit with a visual, or some other time constraint. And lastly, but perhaps more importantly, there is the guitarist who works as a sound designer. Perhaps he or she doesn't get enough time away from the computer to always be in top shape. As music gets more and more ubiquitous in our culture, it also gets 'cheaper by the pound' if you will, since more people are competing for fewer dollars. Very often the budget for a decent studio, engineer and player just isn't there, and the sound designer is caught in the vice of having to produce a real-sounding track with the wrong gear. A good soundfont can save the day.
Regarding instruments, I use a Godin Jazz, Godin ACS nylon, and a Roland GK-2a pickup, which I move around between my G&L Asat and my Northwood OM-60 acoustic. The Godins work very well with the Roland GR-33, as does the GK2a, but it does pay to set the GK-2a up carefully to Roland's instructions. I also have a Gibson Tennessean, but I haven't felt the need to use that for midi work.
If you are going to use a midi equipped guitar for input, it really helps to use at least use the same type (acoustic/electric) as you are trying to imitate. At least then you stand a chance of getting useful decay data (if you want to use it), using the envelope setting on your pitch to midi converter, and perhaps more important, you get the right play feel and physical feedback from the right instrument. I find it difficult to play the Mixed Bag demo piece on an electric guitar. It just doesn't feel right. Since I move my GK-2a around quite a bit, I use that reusable adhesive (some folks call it dum-dum) to temporarily mount the pickup on my flat-top acoustic. You can use fairly thick lumps of it, which eliminates the need for shims, and it doesn't mar the finish on the instrument. To mount the controller and jack module, I just use a couple of bits of double sided carpet tape. This certainly doesn't constitute a Roland approved GK2a installation! And you will see in the demo editing that I pay for it when it comes editing time, but it gets the job done.
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Some Basic Editing Suggestions
There are lot's of sites on the net where you can find editing pointers that are platform and program specific, so I won't try that here. These are just a few points I haven't seen elsewhere.
Do your editing at a very slow tempo. This is midi! Take full advantage of it. If your sequencer has a tempo track as well as a fixed tempo, you can set one at the final tempo for the tune and the other at a slower tempo, maybe half the final.
Try not to delete too many notes at first. Mute them if necessary. You may want them later.
And bear in mind that sometimes it will make sense just to reduce their velocities to something really low. A little extra noise can be a good thing. Play with the velocities and try different presets for these notes.
You can use a the logical editor in Cubase to achieve this: You could try Transform - Notes - And - Length - Less than 50 - Target - Value 2 - Divide by 2, as a starting point.
Speaking of editors, the Key Editor or Piano Roll is at first, the friendliest looking. It's a great tool for having a graphical view of the file, for seeing the pitch, overlaps, lengths and channels of notes. It's also great for inputting notes with the mouse, and drawing continuous controller data, like pitch bends. You could do just about all your editing there, but if you did, you'd be missing out on some of the great things the List Editor has to offer.
The List Editor provides a data view of the Midi file, and with this tool you can easily create sets of Controller Change data like Attack Time, Decay Time and Brightness, which are the ones I use most often. Having set up the file with notes, overlaps etc., in the Key Editor, I like to move to the List Editor to get to the details. It's easy there to create say an attack time message and then copy and paste it to affect specific notes for fixing slides, turns, hammer-ons and pull-offs. I also find it easier to make decisions about individual note velocities in a data view. It's just a personal preference, but I do like numbers.
For doing large scale edits, like separating all notes by pitch, or location (on the beat - off the beat) to different channel, the Logical Editor is king. Almost any time when you need to collect a group of notes that share a common property, be it channel, length, velocity, location within the bar, the Logical Editor lets you select them efficiently and change some aspect of their data. It's especially preferable to the Key and List Editors, when that selection set consists of non-consecutive notes. And by keeping track of the base Attack Time, Release Time and Brightness values, you'll be able to select those values throughout the file and change them with a single command. You can also develop a whole battery of presets that you use frequently.
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Common Guitar Editing Problems
Say, for instance, you have a 2 fret slide-up ( let's say F# to G# on the 4th string). The midi input will faithfully print each note it sees, including the G natural, but that's not what you want to hear. If you delete the G natural, it sounds too clean, too abrupt. If you just lower the velocity on the G natural, it leaves a hole in the sound, but if you drag the length of the F# so it rings over the velocity-reduced G natural, it begins to give a better approximation of what you heard from the guitar. One thing we need to consider here is reverberation -not of the room you're recording in, but in the guitar box. The shortest note you can play will always ring some time after you release the string. The midi pick-up doesn't really catch the full length of this because it has it's own threshold for recording the start and stop of a note(the midi note will be cut off when this threshold is reached, even though the sound is still there in the guitar). What I'm getting at here is that when you play that slide, for an instant you will hear the F# and the G natural ringing together, even though they are played on the same string. You need to let the midi file reflect that.
When I edited the Mixed Bag audio demo, I experimented with selecting all the notes in the track and lengthening the whole bunch of them so the short ones overlapped, just a bit. It generally helped to smooth out the sound and make it more guitar-like, but it's no silver bullet. Every edit needs to be assessed on its own merits.
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Mimicking The Acoustic Guitar's Interior Reverberation
A couple of paragraphs ago, I mentioned the reverberation that takes place inside the guitar box. I suppose this is a matter of opinion, but I think one of the shortcomings of recording single note samples from acoustic guitars, is that they tend not to carry the same reverberation in the guitar box as is there in the act of normal playing. This comes about from muting all strings except the one being sampled. In a real playing situation there will often be open or fretted strings that are free to ring sympathetically with the struck note. This sympathetic ringing will both colour the sound of the struck note, and carry over a bit when the note is stopped.
I've experimented mainly with release times as a method of dealing with this, but the best success so far has been controlling release times in combination with the use of an inserted impulse reverb. I can't recommend Voxengo Pristine Space highly enough. You'll also note in the mixer sections of the demo editing articles that I'm a Voxengo addict anyway. Another very nice free impulse reverb is SIR.
The multi-channel capability of Pristine Space is really handy. On the Noisevault site, you'll find impulse responses of a piano and guitar. In both cases the instrument was struck with a ceramic spoon, and the ringing of the strings afterward was recorded. The guitar responses were recorded near and far, so there are 2 versions. With Pristine Space, you can load them both, and apply them to the track.
Here are some screenshots form some early experiments with PS used as a send effect:
PS Slot with Uprite piano impulse from Noisevault available here.
Pristine Space Impulse Reverb Plugin Slot 2 with Derlon Santuary impulse, also available on the Voxengo Site
Pristine Space Impulse Reverb Plugin Slot 2 with EQ settings for Derlon Santuary impulse.
You may also find the free plugin, Pianoverb available at www.pspaudioware.comuseful.
I've tried using it as an insert rather than a send with no more than about 18% effect, quite short decay times and a very slight downward detune. Here's a screen shot of the settings I used on some early versions of the demos.
Once I get an acceptable 'dry' sound using Pianoverb I send that mix to the reverb of choice for room effects. I'd really like to see a 'Guitarverb' based on the same design concept -especially if it could analyze the current harmonic structure and provide a resonance based on the available open and fretted strings.
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Using Notation Programs
I frequently find that it's easier to start a midi file in a notation program like Finale. This may be because I already have a lead sheet for the song, or it may have been easier to flesh out my musical ideas in notation first before even thinking about the midi or audio processes. Sometimes for me, the midi file is just a side issue, and the notation is what I'm really after, so I can take the charts to a gig. I also work with quite q few vocalists, and it's often handy to be able to give them a midi file of a song to rehearse with, so then the notation is important so the musicians will play it the way the vocalist has rehearsed it.
Most notation programs have midi export functions, which allow you to export type 0 or type 1 midi files (usually both are supported). They also commonly have rhythm section generators that can automatically generate drum, bass and piano parts according to the chord changes you specified which can be a useful starting point once exported in to your sequencer. The rhythmic possibilities of these generators are limited, but they can reduce some of the more repetitive work out of building rhythm section parts in a piano roll. If you're going to go this route, it really pays to organize your work so you get all the work you want done in one program before exporting to the next. Juggling files back and forth can quickly make you wish you'd just started in the sequencer and stayed there.
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Last updated Feb 1/06 19:00 MST
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