Logic Pro X: FREE Script for Incredible New Scripter MIDI FX Plug-In

An unsung hero in Logic Pro X is the Scripter MIDI FX Plug-in. Using JavaScript you can create your own MIDI FX. Peter Schwartz (Mr Environment to his friends) has created a special one to download.  

With the advent of Logic Pro X, many a Logic user's long-awaited prayers have been answered: arpeggiators, MIDI delays, chord memorizers, and other MIDI-based effects no longer need to be painstakingly created in the Environment and literally wired up by hand. They've been effectively replaced by a new series of MIDI FX plug-ins that you insert right in an Instrument channel strip '" up to 8 per strip!

Logic Pro X's new Instrument Channel Strip, shown here with four MIDI FX.

Logic Pro X's new Instrument Channel Strip, shown here with four MIDI FX.

Apple's Logic development team has done a superlative job creating a highly useful suite MIDI FX with modern-looking GUI's.

The new Arpeggiator and Chord Trigger plugins

The new Arpeggiator and Chord Trigger plug-ins.

A Nail In the Environment's Coffin?

Included in the FX collection is a new plug-in that effectively eliminates 95% of the need to use the Environment for MIDI processing. For me, it's the most exciting plug-in in the collection, one that lets us write our own custom MIDI plug-ins! It's called the Scripter. 

Figure 1: The custom appearance of the GUI for the free script linked in this article!

Figure 1: The custom appearance of the GUI for the free script linked in this article!

The Scripter Plug-in


Peter Schwartz, composer, orchestrator, arranger, pianist, synthesist, and musical director, began piano studies at age 5 and went on to earn a degree in piano performance from Manhattan School of Music. It wasn't long afterward that he began working as a product specialist for New England Digital (Synclavier) and also as a sound progr... Read More


Peter Schwartz thank you for the gift. Incredible.
Great stuff! Thank you for that. Give us more scripts, I think there is a lot of power in the scripter plugin.

Best regards,
More of this, please!


This was one of my favorite updates off of the bat on Logic Pro X
Amazing! Thanks so much!
Magic Fingers
Wow!!! are you kidding me? Logic Pro X is taking away the need to learn several 3rd party apps and become exhausted with learning environment tricks (stuff that I am doing daily in LP9), and it's all under one hood now. I can't wait to upgrade my operating system so I can take advantage of all these new features. Way to go Logic Pro!!!
Magic Fingers
Wow!!! are you kidding me? Logic Pro X is taking away the need to learn several 3rd party apps and become exhausted with learning environment tricks (stuff that I am doing daily in LP9), and it's all under one hood now. I can't wait to upgrade my operating system so I can take advantage of all these new features. Way to go Logic Pro!!!
Peter Schwartz
I'm really glad you guys are digging this, and getting insight and inspiration as to what Scripting can do.
Cyril Blanc
I was looking to access Meta data to handle score accidents
Did you find the trick ?

Peter Schwartz
It does not seem possible to generate Meta or Fader events from a script.

Even if it was possible, you can't use Scripts to process data before it enters Logic (at the Sequencer Input object in the Environment), and that is the ONLY place where Meta events can be passed into Logic for the purpose of recording them on a track. Since you can't insert a Script in any object in the Environment, and since Scripts can't generate Meta events anyway, it's just not possible.

Now, you can still attempt to use Environment objects to generate Meta events (for score symbols or whatever) and feed them into the Sequencer Input. However, it will be an exercise in futility. Or, I should say, in Logic 9 and prior it was futile, because something in the code prevented that from working. I haven't tried it in Logic X tho. If I get a chance I will and post back here if I get a positive result.
Cyril Blanc
Hello Sky

Thanks for your answer.

I do not want to generate meta, but read Meta that are in the score to send changes of articulation in Vienna Symphonic Library first, I may also extend it to Play and .......

It will look like this :

If Meta = "Legato" then send "C0"
If Meta = "Staccato" then send "C#0
if Meta = "pppp" then send "ctrl 7 with value 20"
if Meta = "ppp" then send "ctrl 7 with value 30"
if Meta = "pp" then send "ctrl 7 with value 40"
if Meta = "p" then send "ctrl 7 with value 50"
if Meta = "f" then send "ctrl 7 with value "64"

So how can you read Meta ?
Do you have the list of the Meta with there code ?

Thanks in advance


Peter Schwartz
Scripts cannot read Meta Events, so you're out of luck there.

I believe it's possible to do this directly in the environment. However, I'd like to suggest that the idea of associating dynamic markings with specific values sounds good in theory but isn't a practical approach. First, just adjusting the volume (CC#7) won't give your parts a natural sound. Second, if you had a sudden (subito) jump from "p" to "f" and any of the "p" notes overlapped even slightly into the "f" part, the transition is going to sound unnatural.

While riding volume alone won't give you an very natural sound, it's better than nothing, and in that case I'd suggest riding automation on your parts to match the dynamics you want.

If you want natural dynamics from Vienna stuff, you have to use a combination of riding the values of velocity xfade, the filter, and volume. But that's a whole other subject. :)
Cyril Blanc
Hi Ski

Thanks for your mail

> Scripts cannot read Meta Events, so you're out of luck there.

So this Scripter IS A PIECE OF S.....



WE ARE Thousands USERS USING VSL, QLSO ... and that are needing to drive articulation changes from score
Cyril is right... the Scriptor is Totally Useless.... First i thought... yeah great ... then i began to script articulation switches.... everything is just recordable into the Automation ... I dont need something like this ... i need the midi data or the Meta Events, recorded into the file... not into the Automation....
Cyril Blanc
Cubase, Notation, Sibelius, Finale has listen to there user. They are totally interfaced with VSL, Play .....

Cubase has the VST Expression Map since more than a year !

Logic is behind ! shame !!!!!!!!!

I am still downloading Logic X on a very slow connection so as of yet I cannot tell for myself but I have a question:

Can I, for example, make a script that SOMETIMES plays one chord and sometimes another given a single note AND actually 'use' that data?

From the article:

Scripts, like all other MIDI FX, are non-destructive insert FX: they are always “live” and intercept MIDI data after it enters the instrument channel but before it arrives the instrument plug-in itself. So when you record a part, the track will contain only your original notes and controllers, just as in the example recording. In fact, if you examine the Event List in the example project you’ll see that it only contains notes. During performance or playback, however, the Script generates additional MIDI data that tells EXS which articulations to trigger for notes above and below the split.

My question is: Can I record or save somehow the additional MIDI data for later use? eg editing?

I hope this makes sense
Cyril Blanc
you can do this with the environment already
Peter Schwartz
Hi Dave, what you said totally makes sense, and you've got it exactly right. Scripting and other MIDI FX are "non-destructive" and therefore only process MIDI data entering the software instrument's channel strip. What you'll see in a region is the data as it originally came into the software instrument's channel strip. But within the channel strip, the MIDI is processed on its way to the plugin instrument.

Recording the output of the process (i.e., the output of the Script) is proving problematic. In fact, I've been working hard trying to find a foolproof way to record the output of a Script without any kind of "gotchas". I think I'm making progress, so "please stand by". :)
Peter Schwartz
Cyril, can you explain how you do this in the environment? Are you talking about using IAC?
Cyril Blanc
You do that with "chord memorizer "

You can add "transformers" that will select different "chord memorizer " depending of either a CC change or a specific note range

Have one in Minor, another one in Major, another in Major 7 ........

If you want to record the result you send the end of the chain to another midi instrument and record it
Peter Schwartz
Just read your reply. I don't believe your idea will work, because you can't record the output of an instrument. So if you cabled your environment process to another MIDI instrument, it would play that instrument but it wouldn't be recorded.
Cyril Blanc
to record if it does not work connect to sequencer input
Hi Peter,

Thanks for the awesome little script, however for some reason I cannot get it to work properly.

I am literally copying and pasting the script from the file in your article into the scripter in a new project in Logic Pro x (I have even saved it as a preset in the script window).

Basically when I run the script, the GUI/front end loads up the two boxes to select the play methods (legato, pizzicato etc) and the Split note (e.g. C3) but it doesnt seem to actually split the keyboard - or change the sound according to the play methods I select. When I looked in the script, it says the following
Pluginparemeter[0] missing unit
Pluginparemeter[3] missing unit

Which I assume is the above split and below split paremeters not working properly.

I am a bit of a code newb so not sure how, in the process of my copy and paste, I am getting this wrong haha

Any info appreciated.

Thanks in advance

P.S do you know of anywhere we can get more scripts like this - been looking around and not much available.

Peter Schwartz
Hi Chris, sorry you're having trouble with it. The messages you see about the missing unit in the Plugin Parameter are benign. However, I've gone and changed the code so that it no longer reports that message. It's working 100% as far as I can tell at 3:30 in the morning.

I'm going to post a new message after this one with the new code. You can copy and paste it into the Scripter. Then, hit "Run Script". It should work 100% fine. If not, post back.

Regarding other Scripts, it's early days yet. Presently there are problems associated with having too many scripts in a project which apparently Apple is aware of. But I'm pressing on all the same, and have a variety of plugins that I'm developing to do all kinds of neat stuff.
Peter Schwartz

function HandleMIDI(e) {

var sus = new ControlChange;

if (e instanceof NoteOn > 0) {
if (e.pitch < GetParameter("Split Point")) {
sus.number = 1;
sus.value = (GetParameter("Below Split")*25);
} else {
sus.number = 1;
sus.value = (GetParameter("Above Split")*25);

var PluginParameters = [

{name:"MacProVideo", type:"menu",unit:"blobs",minValue:0,maxValue:1,numberOfSteps:2,defaultValue:1,

{name:"Above Split", type:"menu", unit:"blobs",minValue:0,maxValue:5,numberOfSteps:6,defaultValue:1 ,
valueStrings:["Legato","Staccato", "Pizzicato","Tremolo","H.Trill","W.Trill"]},

{name:"Split Point", type:"menu", unit:"blobs",minValue:0,maxValue:127,numberOfSteps:128,defaultValue:60,

{name:"Below Split", type:"menu",unit:"blobs", minValue:0, maxValue:5, numberOfSteps:6, defaultValue:0,
valueStrings:["Legato","Staccato", "Pizzicato","Tremolo","H.Trill","W.Trill"]}];
Thanks for this. I tried the new code and alas still no love.

Perhaps its something to do with the setup of my instrumentation - I am going into EXS24 > Orchestral > Strings > FullStings+ right?

I have tried Stereo and Multi output versions - but still get the same result.

Basically, the scripter says it works (so no more missing plugins) but seems to be sticking to the default sound that loads up when the sampleter starts (i.e. doesnt change when I change the selections in the scripter)

not sure how the flipping flip I am going wrong with this...

Cheers for your help

Peter Schwartz
Gonna suggest that you download the project from the link above (it's been updated with the new code) and save the Channel Strip as a new Channel Strip Setting.

Note that the script won't work unless Full Strings+ is modified as shown in the picture above, so the easiest move would be to save this as a Channel Strip Setting. No need to copy and paste code to make it work.

Also, just for the record (wink) there weren't any missing plugins. The original code worked fine. I just didn't specify a few non-critical parameters that resulted in what appeared to be error messages but had no bearing on how well the script worked.
Boom. That did it. Nice one, thanks.

Is this script limited to just FullStrings+ in EXS or are there other ways it can be tweaked?

Awesome job though, sounds great with the two 'multis' at the same time.


Peter Schwartz
Hi Chris,

Glad it's working for you.

Yes, this script can be used with any EXS-24 instrument that has multiple samples (articulations) where each one is programmed within the EXS instrument itself to have a unique Articulation ID. Critical to the operation is setting the EXS's modulation matrix as shown above.

Full Strings+ has 6 articulations, and the value of 25 you see in the code specifically addresses having six Articulation ID's. If an instrument had a greater or lesser number of articulations, that value would have to be adjusted (and so would the labels in the menus).
Thanks all
Trying to write a script to filter the channel strip incoming midi channel (like environment's channel splitter.any ideas?
thanks again
I've followed Ski's method laid out in another forum thread to allow for more expressive playing of stock EXS strings using the modwheel (thanks!). But does anyone know if you can program a script that approximates this with non-Logic EXS instruments like Garritan or Sonatina Symphonic Orchestra? Some of these free or cheap libraries could work much better I feel if we could impose the same filter cutoff and volume tweaks using the mod wheel for better expression. Thanks in advance!
Thanks Peter for these insights. I have to say though, it would be nice to have a MacProVideo tutorial about the Logic Scripter. For someone who comes from the musicians side it's quite difficult to get into coding JS/Midi... But this looks really promising I think. Enormous potential this scripture has! (Greetings from Yoda) U

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