Automatic rests by quantisation from chord-seq to voice


For some reason when I quantize my chord-seq to voice, voice never shows rests. Employing true-durations does not change a thing. (Sometimes when the the chord-seq has a rest at the beginning, but it never does not show rests after.) Is there a trick about that? (I, ve tried with older versions of OM, but always the same.)

Please, I have an urgent need for answer to this question!

Many regards!


Hi Aliser,

First of all , a chord-seq is not necessarly a single voice. It could be a polyphony, i.e durations may overlap.
So , you need to use a single “voiced” chord-seq ( without overlapping durations), if not there’s of course a trick. (we will come to that later…)
Then, there’s an old old known issue concerning the connection of a chord-seq directly into a self’s voice input. This won’t give any rests, even if the chord-seq is correctly used as a single voice.
What i propose to you is to send me a small example and i will send you a patch showing how to do this.


Dear Karim,

Thank you for your quick answer!

Here I send you a patch.

Also, since quantization is not very (or it is too much) precise I am planing to write the rhythm as first in Sibelius and than to import it in OM. Yet, all my filtration patches (E.g. filtering single notes to rests) I was doing in chord-seq based on sequential order of notes. Is it possible to make something like this with voice? (Beside this I was usually working with harmonic score objects and voices and poly I was using “only” to “translate” the material to symbolic notation. So I am not so familiar with rhythm-trees.)

Thank you very much once more!

patch-for-Karim.omp (1.73 MB)

Dear Alizer,

No prob.
Well your chord-seq looks good, no overlapping durations.
So all you need to do is use true-durations and omquantify as shown in the patch attached and you will get your rests!
Of course , you could tune your parameters in omquantfy in order to get what you feel the most approching to your chord-seq.

Now for your filtrereing problem , of course you can do it with voice in conjunction with the Rhythm trees. It is just trickier. but works good. Just state clearly your problem and we can do something with it. By the wayin your patch , theres linked patches missing.


patch-for-Karim-from-aliser-1.omp (2.31 MB)

Dear Karim,

Thank you once more.

Considering the question of filtering voice:
My rhythm filters are based on the on the position of the element in the list.
That is, the notes on a certain position (selected by filter) are changed to rests.

list: (1 2 3 4 5 6 7 8 9 10)
filter positions: (0 5 7 9)
->(1 6 8 10)

Is it possible to filter rhythm in voice in this way? (Of course, the corresponding pitches will be filtered in a cord-seq and subsequently connected to pitch input in voice.)

If its possible (and I really hope it is), please, tell me how! It is pretty urgent for me.

Many regards and thank you for your kindness!


Hi Alister,

yes will send you a patch ASAP…

Hi Alister,

Is this what you need ? (c.f attachment)


aliser-filter.omp (14.9 KB)

Dear Karim,

Million times thank you!

Yes, that’s the patch I was looking for!


Dear Karim, (or anybody who can help me),

The patch you have send to me seems to work only for simple filtration.
Here I am sending it you a patch where each 5th, 7th, 9th & 11th note should be filtered. Yet, the filtration seems to behave somehow erratic.

(Please, check for example bars 83/84!)

What is wrong there?

I trusted that it will function, so I am again in a problem!

Many regards!

PS. I am working with OM6.8, MacOS 10.7

patch-for-Karim-2.omp (338 Bytes)

Dear Aliser,

The patch you have sent me is empty !
PLease do send it , and i will look into it afap.


Dear Karim,

Here the patch again. I don’t know what happened!

patch-for-Karim-21.omp (586 KB)

I see the problem!
It’s in your posn-filter subpatch.
You see the positions should be progressive positions. So if you evaluate the posn-filter, you will see that the values are not progressive (croissant in french)…
So you should order them in a progressive order and remove the duplicates.

Will send you the fix…



Here it is !
It’s my fault… after all. However, you should sort the list. (c.f patch).
I am also including a new function that is more accurate for this case than the filter tree.
The problem is that filter tree takes into consideration some tied.rests etc… select-tree is more specific. I will ask Jean Bresson (dev of OM) to add it to the menu of score/trees…

So for the time being just drop the select-tree.lisp file in the patches folder of your om folder, THEN open the patch. You’ll have the function ready to go.

PLease do report if you encounter another problem.


patch-for-karim-22.omp (652 KB)

Dear Karim,

Thank you.You helped me out again!
(The think with sorted-list was just a mistake in haste. Sorry!)

All the best!


No trouble.
Tell me if it works out good.
And good music!


Dear Karim,

I would be curious to know the ‘trick’ to display polyphonic overlapping in a voice when using a chord-seq with such overlapping notes.

Thank you in advance for your help!

Dear Jimmie,

I don’t think it is possible to “display” visually these polyphonies in a voice. But i might have misunderstood your question. You were referring to a five year old discussion. Could you be more specific>


Dear Karim,

Thank you for the quick follow-up! I was referring to your first reply up this post: ‘‘First of all , a chord-seq is not necessarly a single voice. It could be a polyphony, i.e durations may overlap.
So , you need to use a single “voiced” chord-seq ( without overlapping durations), if not there’s of course a trick. (we will come to that later…)’’

I thought you might have been talking about what I was looking for, that is being able to convert a chord-seq with overlapping notes into a voice that would display chords-and tied notes accordingly (see image as an example).

I was about to try to devise a way to do that, but if there’s a trick, I’d take it!!

Thank you again,


Oh I see. But unfortunately this is not possible in a voice in openmusic. What is possible to do is parse the chord-seq into multiple voices. This is possible. It is also possible (i think it is what i was referring to), to trim the polyphony so you have basically a one voice even with chords but no overlapp. This is due to the structure of all music objects.The chord, chord-seq, multi-seq classes move in parrallel with voice and poly, but they don’t behave the same in all matters. Since these last ones as you know have the notational extra structure.
What do you need exactly , and why ? THese are basically the question you need to ask yourself. Keep in mind, the voice object is not a score. It mimics the symbolic representation, but it try to keep the music classes inside clear. One voice is one voice. So maybe you shoyuld use a poly. And if you need to transcribe it into a polyphonic ONE STAFF score, there;s no automatic wayunfortunately. Like Piano staves. THese are the most complicated to deel even with all the notational applications that exists.

Yes, as you say, it’s the ‘piano way’ that I am looking for… I can imagine a few options to do that, for instance ’slicing’ the music into a common denominator basic unit so that chords are created, and then recreate the longer values and ties afterwards… Well, I’ll see!

Thank you for the clarifications,

Best regards,