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#1884670 - 04/22/12 10:41 PM Re: Sampled VS Modelled Pianos ??? [Re: voxpops]
MacMacMac Offline
3000 Post Club Member

Registered: 09/24/09
Posts: 3788
Loc: North Carolina
Originally Posted By: voxpops
You'd be very aware of it if there were only 127 positions between you and the kitchen.
Maybe yes, maybe no. You might not be aware of just how close I am to the kitchen! smile

Quote:
You could enter a robot dance contest!
That describes me perfectly, first thing in the morning when I've not yet had my first coffee. smile Under those circumstances, I couldn't tell the difference between 2 steps or 127 steps or 1000 steps.

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#1884674 - 04/22/12 10:48 PM Re: Sampled VS Modelled Pianos ??? [Re: musicmad]
gvfarns Offline
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Posts: 3483
Loc: Pennsylvania
I think this one got carried away a little into argument for argument's sake. The original (well, kind of) question is whether 127 is too few levels for playing.

I think it's been accepted that 127 can be too few for recording and studio work. Also that more than 127 won't hurt anything.

Is it too few for piano playing? We can't really test without a piano that can do 127 and more than 127. I think both sides accept that it might be or it might not. Whether your gut tells you it might be enough or whether it says it might not, it's really just a gut feeling because we can't distinguish this limitation from other limitations in our pianos or software.

Unfortunately the available hardware and software doesn't allow the hypothesis to be examined any more closely. I'd love to know, but I don't see it happening. The rest is just arguments about semantics, isn't it?


Edited by gvfarns (04/22/12 10:48 PM)

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#1884675 - 04/22/12 10:50 PM Re: Sampled VS Modelled Pianos ??? [Re: musicmad]
voxpops Offline
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Registered: 03/20/07
Posts: 3021
Loc: Oregon
That's actually an interesting theory, which would suggest that the world is more akin to a digital representation than we might like to think. As with the "spin" of a quantum particle it is either one way or another, but never anything in between - rather like the zeros and ones of computing. And that would also suggest that the driving force is mathematics. Trouble is if you try to imagine what's between the minimum spaces you get tied in mental knots.

(this relates to the posts prior to the last two!)


Edited by voxpops (04/22/12 10:53 PM)
_________________________
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#1884693 - 04/22/12 11:34 PM Re: Sampled VS Modelled Pianos ??? [Re: Macy]
anotherscott Online   content
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Registered: 02/20/10
Posts: 3159
Originally Posted By: Macy
It makes ZERO difference that a player can't hit specific target velocities on demand.

Then we do agree to at least some extent, that "the value of a velocity point's existence is not predicated on the player's ability to produce that velocity at will." But I am not differentiating between being able to hit velocity x on demand, and being able to hit the same velocity twice in a row, which I think is the distinction you are making. The way I see it, either way, we're talking about the value of providing a velocity response point that is beyond the player's motor ability to reliably reproduce.

I guess my question, then, is, whether or not you think there is value in providing velocities that are within the "margin of noise." That is, if your attempts to repeat a note at the same velocity can regularly result in velocities that are 9 or 10 units off from one another, is it or is it not worthwhile to have all those in-between velocities available in the first place? I think you and MMM have suggested that, if they are beyond your ability to exercise control over (i.e. your attempt to generate one will as likely generate one of the others anyway), their existence is moot; whereas I am suggesting that they are still valuable, and would clearly make their presence known as you crescendo'd through the range.

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#1884698 - 04/22/12 11:47 PM Re: Sampled VS Modelled Pianos ??? [Re: gvfarns]
anotherscott Online   content
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Registered: 02/20/10
Posts: 3159
Originally Posted By: gvfarns
We can't really test without a piano that can do 127 and more than 127. I think both sides accept that it might be or it might not. Whether your gut tells you it might be enough or whether it says it might not, it's really just a gut feeling because we can't distinguish this limitation from other limitations in our pianos or software.

Unfortunately the available hardware and software doesn't allow the hypothesis to be examined any more closely.


Someone could play a VAX77 and Pianoteq with its 14,000 point resolution, or with 127 point resolution, and see if they could reliably tell which one they were playing, that might at least provide a clue...

As for unprovable gut feelings, my own is that the reduced expressivity of digital pianos compared to acoustics is at least as much a result of imperfection in translating our finger motions to the 127 points as it is to the limitation of there being only 127 points.

As an aside, in my experience, some acoustic pianos exhibit noticeably more timbral change at different velocities than others do. Though even pianos with lesser dynamic tonal variation still undeniably feel like real, acoustic instruments!

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#1884764 - 04/23/12 03:51 AM Re: Sampled VS Modelled Pianos ??? [Re: gvfarns]
sullivang Online   blank
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Registered: 07/05/09
Posts: 2191
Loc: Sydney, Australia
Originally Posted By: gvfarns
We can't really test without a piano that can do 127 and more than 127.


It is very easy to test with with less than 127, though. Just quantise the MIDI signal to whatever degree you want. Just perhaps, we may not even notice a difference with a 6 bit quantisation (63 steps). If we reach a point where we do notice a difference, introducing dithering to that signal may restore the overall experience to approximately what it was at a higher number of steps. I.e - there may be a point where the quantisation of our (human) random noise becomes audible, yet, we are in fact capturing the intended velocity with enough precision. Dithering allows the intermediate steps to be randomly invoked, hopefully in a fashion as if the velocity were being captured with higher precision at the outset.

If the goal is to reproduce any given performance very accurately, then that changes everything. In this case, the velocity "noise" may not be noise at all, if it causes audible differences. It doesn't matter if the performer can't reliably reproduce that same performance at will - we want to capture that performance as accurately as possible.

Greg.


Edited by sullivang (04/23/12 04:05 AM)

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#1884783 - 04/23/12 04:41 AM Re: Sampled VS Modelled Pianos ??? [Re: anotherscott]
Macy Offline
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Registered: 03/09/10
Posts: 605
Originally Posted By: anotherscott
Originally Posted By: Macy
It makes ZERO difference that a player can't hit specific target velocities on demand.

Then we do agree to at least some extent, that "the value of a velocity point's existence is not predicated on the player's ability to produce that velocity at will." But I am not differentiating between being able to hit velocity x on demand, and being able to hit the same velocity twice in a row, which I think is the distinction you are making. The way I see it, either way, we're talking about the value of providing a velocity response point that is beyond the player's motor ability to reliably reproduce.

Yes, I agree that we are talking about the value of providing velocity quantization that I think is beyond a players motor ability to reliably produce. For the purposes of my model, it is only important that the player can't hit the same set of velocities every time the play the same piece of music, so I'm not concerned whether there is any distinction between that and hitting a specified target velocity.

Originally Posted By: anotherscott
I guess my question, then, is, whether or not you think there is value in providing velocities that are within the "margin of noise." That is, if your attempts to repeat a note at the same velocity can regularly result in velocities that are 9 or 10 units off from one another, is it or is it not worthwhile to have all those in-between velocities available in the first place? I think you and MMM have suggested that, if they are beyond your ability to exercise control over (i.e. your attempt to generate one will as likely generate one of the others anyway), their existence is moot; whereas I am suggesting that they are still valuable, and would clearly make their presence known as you crescendo'd through the range.

First, let me say thank you for taking the time to understand what I was saying and then considering the merits and issues of that model. I'm reminded of a college professor that once told me that unless you can understand the other person's argument so well that you could switch places and present their argument (without having to believe its merits), you have no business arguing with them in the first place. Hence the first step before arguing with someone is to fully understand what they saying. Unless of course, you are arguing with your wife, which is futile anyway. But I digress ...

To return to your question - yes, I think it is important to provide velocities that are "within the player's margin of noise". But the question ultimately becomes how many velocities within the player's noise margin (i.e. how small should the quantization step size be)? The reasoning is easily understood by considering the MIDI velocity quantization as a second velocity noise source. The player's noise and the quantization noise combine (but not simply additively, we need a little math to combine them) to produce the total velocity noise while playing, i.e. the total uncertainty and randomness of the velocities actually produced. The more MIDI velocity values provided within the player's noise margin (i.e. the smaller the quantization step size) the less quantization "noise" and therefore the less total velocity noise. However, there are non-linear diminishing returns. The player's velocity noise will begin to dominate at some point and then making the quantization step size smaller (more levels) doesn't help much more.

An equivalent way of looking at the quantization noise is to simply realize that the player is producing an analog key velocity with analog velocity noise (due to motor abilities) and the sum of those elements is being digitized with a quantization error set by the MIDI quantization step size. So we want to reduce the quantization step size until their are multiple quantization steps within the player's noise and the player's noise is dominant. We want to set a digital noise floor that is below the player's analog noise floor, but as the quantization becomes smaller the digital noise floor will be essentially hidden below the analog velocity noise. We have a wealth of analytical (mathematical) tools that we can apply to understanding the digitization characteristics of analog velocity "signals" just as we would apply those tools to designing digitization for analog audio or video signals.

So that's a long way of saying - No you can't eliminate all MIDI values that fall within the player's noise "margin".
_________________________
Macy

CVP-409GP, Vintage D, Ivory II GP's & American Concert D, True Keys American D, Ravenscroft 275, Garritan Authorized Steinway, Alicia's Keys, EWQL Pianos, MainStage, iPad/forScore/PageFlip Cicada, Custom Mac MIDI/Audio Software Design, Macs Everywhere

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#1884790 - 04/23/12 04:57 AM Re: Sampled VS Modelled Pianos ??? [Re: Macy]
sullivang Online   blank
2000 Post Club Member

Registered: 07/05/09
Posts: 2191
Loc: Sydney, Australia
Originally Posted By: Macy

So that's a long way of saying - No you can't eliminate all MIDI values that fall within the player's noise "margin".


We certainly can eliminate all those intermediate values, if those intermediate values produce neglible change in sound in the instrument. If they produce a noticable change in sound, the there are two ways of solving that problem: a) increasing the resolution with which we sample the velocity (i.e - sample the human noise as well as the human velocity proper), or b) introducing dithering, so that those intermediate steps are invoked in a natural way, as if we had sampled the human noise to begin with.

Greg.


Edited by sullivang (04/23/12 04:58 AM)

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#1884791 - 04/23/12 05:06 AM Re: Sampled VS Modelled Pianos ??? [Re: sullivang]
Macy Offline
500 Post Club Member

Registered: 03/09/10
Posts: 605
Originally Posted By: sullivang
Originally Posted By: gvfarns
We can't really test without a piano that can do 127 and more than 127.


It is very easy to test with with less than 127, though. Just quantise the MIDI signal to whatever degree you want. Just perhaps, we may not even notice a difference with a 6 bit quantisation (63 steps).

You beat me to it.

I was going to suggest taking a MIDI performance file that people agree (ah there's the rub) produces a good result with a particular software piano, and then run that file through a MIDI filter that re-quantizes it to 6-bits instead of 7-bits. We could then record the piano audio from the two examples and post 4 unlabeled audio files, 2 identical files with the 7-bit MIDI and 2 identical files with the 6-bit MIDI, and invite people to a) identify which files are the matching pairs, and b) which files they prefer for piano realism. If people can't identify the matching pairs with statistical significance, we can say that 127 MIDI levels produces no different performance than 63 MIDI levels. But if the group can identify the matching pairs, then we can take the votes of the people that got the matches correct and see whether they thought the 6-bit or 7-bit pairs produced the more realistic piano sound. i.e. we would like to not only know if the pairs were different, but did fewer MIDI levels actually degrade the sound quality.

Maybe someone has time to setup such an experiment. I'm afraid I don't.

Of course, if the group can't statistically identify the matching pairs, we may be in for audiophile A/B testing-like nightmares courtesy of folks that still have some green ink on the rims of their old CDs.


Edited by Macy (04/23/12 05:49 AM)
_________________________
Macy

CVP-409GP, Vintage D, Ivory II GP's & American Concert D, True Keys American D, Ravenscroft 275, Garritan Authorized Steinway, Alicia's Keys, EWQL Pianos, MainStage, iPad/forScore/PageFlip Cicada, Custom Mac MIDI/Audio Software Design, Macs Everywhere

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#1884798 - 04/23/12 05:40 AM Re: Sampled VS Modelled Pianos ??? [Re: musicmad]
sullivang Online   blank
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Registered: 07/05/09
Posts: 2191
Loc: Sydney, Australia
@Macy
Yes, good idea. We could start with a standard Pianoteq preset, and if no difference was detected, try increasing the amplitude and/or timbral dynamic range, and re-run the test etc etc. This test won't determine the precision of human velocity though - it will merely determine the precision required to produce undetectable (or unimportant) differences in the output sound, and only for the particular sounds we test with.

Greg.

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#1884799 - 04/23/12 05:45 AM Re: Sampled VS Modelled Pianos ??? [Re: sullivang]
Macy Offline
500 Post Club Member

Registered: 03/09/10
Posts: 605
Originally Posted By: sullivang
Originally Posted By: Macy

So that's a long way of saying - No you can't eliminate all MIDI values that fall within the player's noise "margin".


We certainly can eliminate all those intermediate values, if those intermediate values produce neglible change in sound in the instrument.


We can't eliminate ALL the MIDI values within the noise component (my original quoted statement above), only those below a level we consider has negligible effects on the player noise and subsequently on the loudness/timbre.

Originally Posted By: sullivang
If they produce a noticable change in sound, the there are two ways of solving that problem: a) increasing the resolution with which we sample the velocity (i.e - sample the human noise as well as the human velocity proper),

That's what our MIDI keyboard already does. It samples/digitizes the human velocity which includes whatever human noise there is. So I'm not quite sure what else you are saying there? Can you clarify?

Originally Posted By: sullivang
or b) introducing dithering, so that those intermediate steps are invoked in a natural way, as if we had sampled the human noise to begin with.

I'm not sure about using dithering in this manner. When we dither audio or video signals we dither frequencies below the Nyquist sampling rate, but here we are taking discrete samples of singular events (once for each key press or note). For instance, in the limit, when we play a single note we can dither the resulting audio sound over 1000's of samples during the second or so that sound is produced from the single key hit. But we can only apply dither to a single MIDI velocity value for that key hit, which accomplishes nothing but introducing a singular error in that particular MIDI velocity. I'm not sure adding dither noise to a succession of "widely-time-spaced" key hit values does anything more than increase the amplitude of the player noise, which isn't an positive effect. Can you expand on what your thinking is for this case?


Edited by Macy (04/23/12 04:42 PM)
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Macy

CVP-409GP, Vintage D, Ivory II GP's & American Concert D, True Keys American D, Ravenscroft 275, Garritan Authorized Steinway, Alicia's Keys, EWQL Pianos, MainStage, iPad/forScore/PageFlip Cicada, Custom Mac MIDI/Audio Software Design, Macs Everywhere

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#1884803 - 04/23/12 06:08 AM Re: Sampled VS Modelled Pianos ??? [Re: musicmad]
sullivang Online   blank
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Posts: 2191
Loc: Sydney, Australia
@Macy:
Let's assume that after careful testing, it is determined that humans can only reliably strike a key at about 16 different velocities. If we ask them to strike with any more precision than that (say, 32 velocities), we find that they're just as likely to strike at velocity value 1 as they are velocity value 2. They will always strike 1 or 2, but they can't strike either of those two velocities with statistical significance. Same goes for 16 & 17, etc etc. Given this, we decide to quantise the velocity to 4 bits, to make our design as efficient as possible.

So, we now feed this 16 step MIDI signal to our nice Disklavier piano, and see how it sounds. wink We may find that certain tone shades which were sometimes invoked by the player before are simply NEVER produced, and this IS noticable. The player can't produce these tone shades on demand, but they notice that now, they can NEVER produce them, and it bothers them.

To solve this problem, I'm asserting that it is entirely valid to superimpose a random signal (with an amplitude of +/- half a step), so that the player is once again able to produce those intermediate tonal shades, in a random fashion, because they were only ever able to produce them in a random fashion to begin with. The required resolution of this new velocity signal will depend on the characteristics of the instrument. This process of adding random noise is called dithering.

The brute force approach, though, is of course simply to increase the sampling resolution, so that the human noise is in fact sampled as well. (and the required resolution again depends on the characteristics of the instrument)

Greg.
p.s I realise that a 4-bit MIDI velocity can in fact only represent 15 velocities, because velocity 0 (zero) cannot be used - 0 means the same as a Note Off. (and this is why a 7-bit velocity has 127 values rather than 128).


Edited by sullivang (04/23/12 09:27 AM)

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#1884906 - 04/23/12 10:10 AM Re: Sampled VS Modelled Pianos ??? [Re: Macy]
voxpops Offline
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Registered: 03/20/07
Posts: 3021
Loc: Oregon
Originally Posted By: Macy
We could then record the piano audio from the two examples and post 4 unlabeled audio files, 2 identical files with the 7-bit MIDI and 2 identical files with the 6-bit MIDI, and invite people to a) identify which files are the matching pairs, and b) which files they prefer for piano realism. If people can't identify the matching pairs with statistical significance, we can say that 127 MIDI levels produces no different performance than 63 MIDI levels. But if the group can identify the matching pairs, then we can take the votes of the people that got the matches correct and see whether they thought the 6-bit or 7-bit pairs produced the more realistic piano sound.


This will tell you only about the listener's experience. It will say nothing about how a performer is affected by the change in quantization. If a performer feels that a piano is somehow not performing as s/he wishes, it will disturb their equilibrium and make it very difficult for them to perform at their best. This is a far more important aspect to this question than the playing back of MIDI files. This is why I said that this argument misses the point. It's not about sound, it's about playability.
_________________________
Occasional author and inveterate ivory tickler:
http://www.amazon.com/author/richardspanswick

https://soundcloud.com/richards-recordings/sets/strange-charm-waiting-for-the/s-ppGuy

"can hardly wait to hear what voxpox has to say..."
[HisKidd, May 2014]

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#1885134 - 04/23/12 04:41 PM Re: Sampled VS Modelled Pianos ??? [Re: sullivang]
Macy Offline
500 Post Club Member

Registered: 03/09/10
Posts: 605
Originally Posted By: sullivang
@Macy:
Let's assume that after careful testing, it is determined that humans can only reliably strike a key at about 16 different velocities. If we ask them to strike with any more precision than that (say, 32 velocities), we find that they're just as likely to strike at velocity value 1 as they are velocity value 2. They will always strike 1 or 2, but they can't strike either of those two velocities with statistical significance. Same goes for 16 & 17, etc etc. Given this, we decide to quantise the velocity to 4 bits, to make our design as efficient as possible.

So, we now feed this 16 step MIDI signal to our nice Disklavier piano, and see how it sounds. wink We may find that certain tone shades which were sometimes invoked by the player before are simply NEVER produced, and this IS noticable. The player can't produce these tone shades on demand, but they notice that now, they can NEVER produce them, and it bothers them.

To solve this problem, I'm asserting that it is entirely valid to superimpose a random signal (with an amplitude of +/- half a step), so that the player is once again able to produce those intermediate tonal shades, in a random fashion, because they were only ever able to produce them in a random fashion to begin with. The required resolution of this new velocity signal will depend on the characteristics of the instrument. This process of adding random noise is called dithering.

The brute force approach, though, is of course simply to increase the sampling resolution, so that the human noise is in fact sampled as well. (and the required resolution again depends on the characteristics of the instrument)

Greg.
p.s I realise that a 4-bit MIDI velocity can in fact only represent 15 velocities, because velocity 0 (zero) cannot be used - 0 means the same as a Note Off. (and this is why a 7-bit velocity has 127 values rather than 128).

Greg,

Thanks for the further explanation. That isn't what we normally think of as dithering and not what I thought you were describing earlier.

What you are describing here is a case where the MIDI quantization would be more coarse (fewer bits) than the the internal sound generator quantization. i.e. in your example the MIDI interface has 4-bits, while the internal samples or other sound generator mechanism might have 7-bits. So by adding random noise to the MIDI velocity values we randomly excite the additional available sound generator bits. I got it now, but that's not usually how dithering is used, which is why I wasn't sure what you were describing earlier.

Dithering is normally used in audio and video when reducing the bit-depth of signals. In other words, instead of having more bits available for the output (as in your example) we have fewer bits in the output than in the input. To avoid the coarseness (and correlation) of the output quantization error (which leads to "harsh" forms of distortion), dither adds noise but makes the output average out to a higher resolution result than the quantization error would otherwise allow. To put it another way, dither allows us to represent an input value with more resolution than the available output bits would normally allow by averaging the output, at the expense of added random noise. Conversely, in your case, a lower resolution number is being randomly converted to a larger set of output values, not to make the output more accurate, but to make it more "interesting". (Of course that means the "feedback" to the player is less accurate as well, but I will leave that for you to debate with voxpops.)
_________________________
Macy

CVP-409GP, Vintage D, Ivory II GP's & American Concert D, True Keys American D, Ravenscroft 275, Garritan Authorized Steinway, Alicia's Keys, EWQL Pianos, MainStage, iPad/forScore/PageFlip Cicada, Custom Mac MIDI/Audio Software Design, Macs Everywhere

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#1885161 - 04/23/12 05:15 PM Re: Sampled VS Modelled Pianos ??? [Re: voxpops]
Macy Offline
500 Post Club Member

Registered: 03/09/10
Posts: 605
Originally Posted By: voxpops
If a performer feels that a piano is somehow not performing as s/he wishes, it will disturb their equilibrium and make it very difficult for them to perform at their best. This is a far more important aspect to this question than the playing back of MIDI files. This is why I said that this argument misses the point. It's not about sound, it's about playability.

Originally Posted By: voxpops
What they want is feedback from the instrument. They want to feel that the response from the instrument matches their input as closely as possible. For the most advanced/sensitive musicians, I would suggest, 127 steps represents only a small fraction of their range of expressive possibilities, and therefore the feedback from an instrument limited in this way frustrates them.

I'm trying to understand why you think you need more MIDI steps for playability.

Please correct me but what I think you are saying is:

1) The player plays a note (or perhaps has played a succession of notes) and has received audio feedback (and maybe tactile feedback) from the note(s) he just played.

2) The player processes the feedback (somehow - consciously or subconsciously) and as a result of that feedback produces some velocity for the next note he plays based on the previous feedback.

3) The 127 MIDI steps are too coarse to allow the player to produce a velocity that results in the sound output he wants to produce in step (2). The errors between the sound output the player wanted to produce in step (2) and the sound output actually produced will "disturb their equilibrium and make it very difficult for them to perform at their best". Therefore, the 127 MIDI steps creates a playability problem.

Is that your reasoning for why 127 MIDI steps creates playability problems?
_________________________
Macy

CVP-409GP, Vintage D, Ivory II GP's & American Concert D, True Keys American D, Ravenscroft 275, Garritan Authorized Steinway, Alicia's Keys, EWQL Pianos, MainStage, iPad/forScore/PageFlip Cicada, Custom Mac MIDI/Audio Software Design, Macs Everywhere

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#1885172 - 04/23/12 05:41 PM Re: Sampled VS Modelled Pianos ??? [Re: musicmad]
ando Offline
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Registered: 11/23/10
Posts: 3523
Loc: Melbourne, Australia
Macy, this idea has been explained ad nauseum by myself and Vox. It's actually very straightforward. This will affect more skilled players (aurally and technically) than the less skilled because the skilled are much more attuned to the input/output balance. If a person is not a skilled player, they would have no real feeling for how this problem manifests and probably doubt its existence as a result.

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#1885176 - 04/23/12 05:43 PM Re: Sampled VS Modelled Pianos ??? [Re: musicmad]
sullivang Online   blank
2000 Post Club Member

Registered: 07/05/09
Posts: 2191
Loc: Sydney, Australia
@Macy:
Thanks! I agree and understand. The process I described is not dithering.

In our case, the human velocity signal is already "dithered" naturally, because of the naturally occurring human noise. So, taking my example, simply quantising the velocity to 15 (16-1) steps is good enough - we don't need to add noise to the velocity signal before we sample it (@4-bits), because we do that naturally.

If the musical instrument we are playing can make audible (interesting/desirable) differences with a step size that is less than our 15 step MIDI velocity, I'm suggesting that simply superimposing a random signal will produce a result that will be indistinguishable to the player and listener. We are synthesizing the non deterministic component of the human velocity.

Perhaps the process I am describing is simply humanization

Quote:

(Of course that means the "feedback" to the player is less accurate as well, but I will leave that for you to debate with voxpops.)


I don't agree with this. The feedback will be just as accurate, because we have sampled the person's desired velocity with sufficient precision. The random part has been added back in, and no-one is any wiser. wink

Greg.


Edited by sullivang (04/23/12 06:14 PM)

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#1885182 - 04/23/12 05:51 PM Re: Sampled VS Modelled Pianos ??? [Re: ando]
Macy Offline
500 Post Club Member

Registered: 03/09/10
Posts: 605
Originally Posted By: ando
Macy, this idea has been explained ad nauseum by myself and Vox. It's actually very straightforward. This will affect more skilled players (aurally and technically) than the less skilled because the skilled are much more attuned to the input/output balance. If a person is not a skilled player, they would have no real feeling for how this problem manifests and probably doubt its existence as a result.

OK. So did I describe your reasoning right or wrong?
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Macy

CVP-409GP, Vintage D, Ivory II GP's & American Concert D, True Keys American D, Ravenscroft 275, Garritan Authorized Steinway, Alicia's Keys, EWQL Pianos, MainStage, iPad/forScore/PageFlip Cicada, Custom Mac MIDI/Audio Software Design, Macs Everywhere

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#1885216 - 04/23/12 06:28 PM Re: Sampled VS Modelled Pianos ??? [Re: Macy]
voxpops Offline
3000 Post Club Member

Registered: 03/20/07
Posts: 3021
Loc: Oregon
Originally Posted By: Macy
Please correct me but what I think you are saying is:

1) The player plays a note (or perhaps has played a succession of notes) and has received audio feedback (and maybe tactile feedback) from the note(s) he just played.

2) The player processes the feedback (somehow - consciously or subconsciously) and as a result of that feedback produces some velocity for the next note he plays based on the previous feedback.

3) The 127 MIDI steps are too coarse to allow the player to produce a velocity that results in the sound output he wants to produce in step (2). The errors between the sound output the player wanted to produce in step (2) and the sound output actually produced will "disturb their equilibrium and make it very difficult for them to perform at their best". Therefore, the 127 MIDI steps creates a playability problem.

Is that your reasoning for why 127 MIDI steps creates playability problems?

That's a very good summary of what I'm saying. With my very mediocre playing ability, I'm able to detect a difference in the way a real acoustic responds to the way a digital does. I can play a (well-maintained) grand with a higher degree of sensitivity than a digital. It's certainly something that I notice less with my FP-7F than with other digitals, so it probably has to do with more than just MIDI velocity steps, but it's still there nonetheless.

Now amplify my skill level to that of a concert pianist of world-class stature (I wish!), at the peak of their performing career. Because their whole system is attuned to the way their instrument responds - their livelihood depends on it - they can detect the most subtle changes in tuning and response, and they are notoriously picky. So far, as far as I know, none has chosen a digital to take on stage with them. What is the reason for that? My conjecture - and it is only conjecture - is that the digital instrument cannot respond sufficiently well to meet their needs. I don't say that it's just velocity resolution - in fact it's more likely to be timbre with sampled pianos - but I really think it's time for a leap forward with all aspects of digitals, and that includes refining the whole system, and making full use of today's computing power. The V-Piano is much more responsive than the average sampled device, and that must be down to the fact that the timbre changes across the whole spectrum of available velocity levels. I believe that it makes use of more than 127 internally, but I cannot be sure, and I may be wrong. Either way, even the mighty V is only seen in the hands of concert pianists paid to endorse this product.

My proposition is this: don't hold back any aspect of DP development in the belief that it's currently good enough. While we may or may not ever see digitals being used for Chopin and Rachmaninoff in Carnegie Hall, it would be a wonderful testament to the designers and engineers if they could be.
_________________________
Occasional author and inveterate ivory tickler:
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#1885220 - 04/23/12 06:44 PM Re: Sampled VS Modelled Pianos ??? [Re: voxpops]
EssBrace Offline
2000 Post Club Member

Registered: 12/01/09
Posts: 2393
Loc: Suffolk, United Kingdom
Originally Posted By: voxpops
With my very mediocre playing ability, I'm able to detect a difference in the way a real acoustic responds to the way a digital does. I can play a (well-maintained) grand with a higher degree of sensitivity than a digital. It's certainly something that I notice less with my FP-7F than with other digitals, so it probably has to do with more than just MIDI velocity steps, but it's still there nonetheless.


I suspect the difference between acoustic and digital is all to do with factors other than the number of MIDI velocities. Or what I should say is that with the current state of the art the MIDI standard is not a significant limiting factor - it's everything else. The difference between a good DP and a bad one can be absolutely night and day - but they are still both using 127 velocities.

When the other DP inadequacies have been successfully addressed, THEN a limiting factor MIGHT be the number of MIDI velocities. I think R&D resources would be better spent by addressing the more obvious DP shortcomings before an overhaul of MIDI specifications needs looking at. Just my thoughts...
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#1885222 - 04/23/12 06:46 PM Re: Sampled VS Modelled Pianos ??? [Re: musicmad]
sullivang Online   blank
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Registered: 07/05/09
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Loc: Sydney, Australia
+1000 to EssBrace.

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#1885225 - 04/23/12 06:54 PM Re: Sampled VS Modelled Pianos ??? [Re: sullivang]
Macy Offline
500 Post Club Member

Registered: 03/09/10
Posts: 605
Originally Posted By: sullivang
In our case, the human velocity signal is already "dithered" naturally, because of the naturally occurring human noise. So, taking my example, simply quantising the velocity to 15 (16-1) steps is good enough - we don't need to add noise to the velocity signal, because we do that naturally.

I guess we have to take this a step at a time for me to understand. Blame it on me for being slow smile

What do you mean by "good enough". Good enough for what? You are quantizing the players analog velocity input. There is always quantizing error (noise) that also contributes to the players noise. Unless you make the quantizing noise significantly less than the human noise it adds additional error to whatever the player was trying to play. (The error is not "dithered" out, there is no averaging of multiple key presses into a single key press.)

Originally Posted By: sullivang
If the musical instrument we are playing can make audible (interesting/desirable) differences with a step size that is less than our 15 step MIDI velocity, I'm suggesting that simply superimposing a random signal will produce a result that will be indistinguishable to the player and listener. We are synthesizing the non determistic component of the human velocity.

What do you mean by "indistinguishable"? Do you mean the signal you created by adding random digital noise to the digitized velocity signal is indistinguishable from digitizing the human signal plus human noise with more MIDI resolution? If so, that isn't true even if the added digital noise is equal to the human noise. The signal you created also includes a much larger quantization error because you reduced the MIDI resolution from 7-bits to 4-bits. You may have "simulated" the human noise part but you increased the quantization noise by using less bits too.

Originally Posted By: sullivang
Quote:

(Of course that means the "feedback" to the player is less accurate as well, but I will leave that for you to debate with voxpops.)

I don't agree with this. The feedback will be just as accurate, because we have sampled the person's desired velocity with sufficient precision. The random part has been added back in, and no-one is any wiser. wink

I'm afraid not. You digitized the analog signal (with the human noise) using less resolution and therefore increased the quantization error too. Then you added your simulated human noise back in again. The result is not the same as digitizing the original analog velocity (with the human noise) using more quantization steps.
_________________________
Macy

CVP-409GP, Vintage D, Ivory II GP's & American Concert D, True Keys American D, Ravenscroft 275, Garritan Authorized Steinway, Alicia's Keys, EWQL Pianos, MainStage, iPad/forScore/PageFlip Cicada, Custom Mac MIDI/Audio Software Design, Macs Everywhere

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#1885245 - 04/23/12 07:24 PM Re: Sampled VS Modelled Pianos ??? [Re: Macy]
sullivang Online   blank
2000 Post Club Member

Registered: 07/05/09
Posts: 2191
Loc: Sydney, Australia
Originally Posted By: Macy

What do you mean by "good enough". Good enough for what? You are quantizing the players analog velocity input. There is always quantizing error (noise) that also contributes to the players noise. Unless you make the quantizing noise significantly less than the human noise it adds additional error to whatever the player was trying to play. (The error is not "dithered" out, there is no averaging of multiple key presses into a single key press.)


Of course the quantisation adds noise. We simply have to sample with sufficient resolution such that this noise is negligible.

Take an extreme example. Let's say a player plays a MIDI keyboard, and they're absolutely hopeless. After careful statistical analysis, we determine that his attempts at hitting any velocity result in white noise. (a random number 1 to 127) Do we need to sample this white noise in order to reproduce the same impression of that player? Of course not. We do not need to send ANY velocity information to our piano whatsoever, and instead, we can simply send a synthesized white noise signal that is created by generating a random number between 1 & 127. (at whatever resolution we think is appropriate)

If we are in fact interested in the precise detail of any given performance of this strange performer, then of course we then need to sample that white noise with whatever precision we deem necessary.

Do you at least agree with me thus far?

Greg.


Edited by sullivang (04/23/12 07:55 PM)

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#1885250 - 04/23/12 07:26 PM Re: Sampled VS Modelled Pianos ??? [Re: musicmad]
gvfarns Offline
3000 Post Club Member

Registered: 04/16/07
Posts: 3483
Loc: Pennsylvania
By the way, does anyone around here actually own a VAX77 and PianoTeq? It sort of gets mentioned a lot as a possibility but I haven't heard anyone talking about theirs, so I'm not sure it's possible for us (meaning the people involved in this discussion...I'm really on the periphery, but I still count myself).

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#1885255 - 04/23/12 07:36 PM Re: Sampled VS Modelled Pianos ??? [Re: voxpops]
Macy Offline
500 Post Club Member

Registered: 03/09/10
Posts: 605
Originally Posted By: voxpops
Originally Posted By: Macy
Please correct me but what I think you are saying is:

1) The player plays a note (or perhaps has played a succession of notes) and has received audio feedback (and maybe tactile feedback) from the note(s) he just played.

2) The player processes the feedback (somehow - consciously or subconsciously) and as a result of that feedback produces some velocity for the next note he plays based on the previous feedback.

3) The 127 MIDI steps are too coarse to allow the player to produce a velocity that results in the sound output he wants to produce in step (2). The errors between the sound output the player wanted to produce in step (2) and the sound output actually produced will "disturb their equilibrium and make it very difficult for them to perform at their best". Therefore, the 127 MIDI steps creates a playability problem.

Is that your reasoning for why 127 MIDI steps creates playability problems?

That's a very good summary of what I'm saying.


Ok, so we will make you a piano with twice as many MIDI steps, so that it has steps 1/2 the size as now. Then in step (2), from the feedback you received in step (1), you will have to be able to precisely produce a velocity for each note that is within 1/2 of the current 127 MIDI step size that you intend to produce for that note, else you will not get the sound from the piano that you intended to produce. Any errors between what you want to produce and what you really produce in step (2) will be more than a 1/2 step and just as coarse (or more coarse) than what you get with 127 MIDI steps. Any errors, will as described in step (3), disturb your equilibrium and you will have the same playability problems described in step (3).

So do you think you can play from note to note with that precision, consciously, subconsciously, or supernaturally? Otherwise, adding more MIDI steps won't solve that playability problem.

Originally Posted By: voxpops
With my very mediocre playing ability, I'm able to detect a difference in the way a real acoustic responds to the way a digital does. I can play a (well-maintained) grand with a higher degree of sensitivity than a digital. It's certainly something that I notice less with my FP-7F than with other digitals, so it probably has to do with more than just MIDI velocity steps, but it's still there nonetheless.


I think we can all tell the difference between the way an acoustic piano and a digital piano responds. I suspect I can think of a dozen better reasons than only having 127 MIDI steps.
_________________________
Macy

CVP-409GP, Vintage D, Ivory II GP's & American Concert D, True Keys American D, Ravenscroft 275, Garritan Authorized Steinway, Alicia's Keys, EWQL Pianos, MainStage, iPad/forScore/PageFlip Cicada, Custom Mac MIDI/Audio Software Design, Macs Everywhere

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#1885260 - 04/23/12 07:48 PM Re: Sampled VS Modelled Pianos ??? [Re: Macy]
voxpops Offline
3000 Post Club Member

Registered: 03/20/07
Posts: 3021
Loc: Oregon
Originally Posted By: Macy
Ok, so we will make you a piano with twice as many MIDI steps, so that it has steps 1/2 the size as now. Then in step (2), from the feedback you received in step (1), you will have to be able to precisely produce a velocity for each note that is within 1/2 of the current 127 MIDI step size that you intend to produce for that note, else you will not get the sound from the piano that you intended to produce. Any errors between what you want to produce and what you really produce in step (2) will be more than a 1/2 step and just as coarse (or more coarse) than what you get with 127 MIDI steps. Any errors, will as described in step (3), disturb your equilibrium and you will have the same playability problems described in step (3).

So do you think you can play from note to note with that precision, consciously, subconsciously, or supernaturally? Otherwise, adding more MIDI steps won't solve that playability problem.


Let's take your reasoning and apply it in the opposite direction. That would imply that the fewer the steps available the more likely I am to be able to play accurately, because I am much more likely to be able to strike at a particular velocity and therefore meet my feedback/restrike criteria. I think 10 steps should do it. wink

Again, that is not the way we play. It would suggest that an acoustic with an "infinite" number of steps available would be impossible to play! The feedback would overwhelm the player because they would become unable to strike anything at the desired level.

No, a player almost subconsciously molds his playing to the input he is receiving. The finer the resolution available, the better he is able to play.


Edited by voxpops (04/23/12 07:50 PM)
_________________________
Occasional author and inveterate ivory tickler:
http://www.amazon.com/author/richardspanswick

https://soundcloud.com/richards-recordings/sets/strange-charm-waiting-for-the/s-ppGuy

"can hardly wait to hear what voxpox has to say..."
[HisKidd, May 2014]

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#1885264 - 04/23/12 07:57 PM Re: Sampled VS Modelled Pianos ??? [Re: sullivang]
Macy Offline
500 Post Club Member

Registered: 03/09/10
Posts: 605
Originally Posted By: sullivang
Originally Posted By: Macy

What do you mean by "good enough". Good enough for what? You are quantizing the players analog velocity input. There is always quantizing error (noise) that also contributes to the players noise. Unless you make the quantizing noise significantly less than the human noise it adds additional error to whatever the player was trying to play. (The error is not "dithered" out, there is no averaging of multiple key presses into a single key press.)


Of course the quantisation adds noise. We simply have to sample with sufficient resolution such that this noise is negligible.

Ok, well I thought that is about where we are today. I can't see reducing MIDI to 6-bits, let alone 4-bits, because I think it would add too much quantization noise. There are certainly people here that would like to increase it to 8-bits or more, which would be fine too if the virtual/digital piano designers would use the extra resolution advantageously. Right now, I see too many examples of not doing 127 levels very well. But suppose they produce some really good sound generation with 8-bit or 9-bit velocity input, then it might be interesting to see what adding some noise bits as you suggest would do with the current MIDI 127 levels.
_________________________
Macy

CVP-409GP, Vintage D, Ivory II GP's & American Concert D, True Keys American D, Ravenscroft 275, Garritan Authorized Steinway, Alicia's Keys, EWQL Pianos, MainStage, iPad/forScore/PageFlip Cicada, Custom Mac MIDI/Audio Software Design, Macs Everywhere

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#1885272 - 04/23/12 08:05 PM Re: Sampled VS Modelled Pianos ??? [Re: musicmad]
sullivang Online   blank
2000 Post Club Member

Registered: 07/05/09
Posts: 2191
Loc: Sydney, Australia
@Macy:
I was simply giving an extreme example, to try and make my point clearer. I don't know how precise humans are at playing a keyboard and generating a velocity signal. It would require very careful testing with many different playing techniques. The feedback to the player should also be very good - perhaps much stronger than a piano - for example, allowing the player to observe the MIDI velocities displayed by a MIDI monitor. This would then cater for a wide range of instruments.

Greg.

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#1885303 - 04/23/12 08:57 PM Re: Sampled VS Modelled Pianos ??? [Re: voxpops]
Macy Offline
500 Post Club Member

Registered: 03/09/10
Posts: 605
Originally Posted By: voxpops
Originally Posted By: Macy
Ok, so we will make you a piano with twice as many MIDI steps, so that it has steps 1/2 the size as now. Then in step (2), from the feedback you received in step (1), you will have to be able to precisely produce a velocity for each note that is within 1/2 of the current 127 MIDI step size that you intend to produce for that note, else you will not get the sound from the piano that you intended to produce. Any errors between what you want to produce and what you really produce in step (2) will be more than a 1/2 step and just as coarse (or more coarse) than what you get with 127 MIDI steps. Any errors, will as described in step (3), disturb your equilibrium and you will have the same playability problems described in step (3).

So do you think you can play from note to note with that precision, consciously, subconsciously, or supernaturally? Otherwise, adding more MIDI steps won't solve that playability problem.


Let's take your reasoning and apply it in the opposite direction. That would imply that the fewer the steps available the more likely I am to be able to play accurately, because I am much more likely to be able to strike at a particular velocity and therefore meet my feedback/restrike criteria. I think 10 steps should do it. wink


True the fewer the steps the more likely that you could hit the steps you intend out of the available steps. The problem is that too few steps will sound awful. Try 3 steps for instance. You won't have much expression because you have so few loudness/timbre choices to play for each note. So we increase the steps to give you more choices and your playing can sound better. Do we continue to 10,000 steps just because we could? At some point, the steps get so small we can no longer control our motor skills well enough to reliably play the steps we would like to play, even assuming we can somehow (consciously or sub-consciously) process the feedback from our playing with enough resolution to intend to play in those smaller steps. We simply can't do it.

Even a machine will have some resolution and tolerance limits. Once we reach the limit of what we control we are simply creating additional randomness (noise) to our performance if we add more steps. Is that good? It might be if we are a mechanical machine that only produces 8 steps, but produces them so precisely we never get anything but those 8 steps. Adding another bit or two (16 or 32 steps) with 1 or 2 steps of noise might make the machines playing seem less mechanical.

Do humans need more steps of randomness than what we have now? We have 127 steps. How many of those can the best pianist use reliably and how many become his noise? I don't know. I've never claimed to know that answer. I just know what I can do. Mac3 postulates, I think, that just adding some more steps of velocity input noise to a higher resolution sound generator might improve a performance. I wonder how the best concert pianist would react to that? We are going to add a little randomness to the existing randomness of your playing to improve it? Not real well, I would guess. smile

Originally Posted By: voxpops
[Again, that is not the way we play.

You can't get away with that any more. I asked you how you played, and then described my understanding of your process, and you agreed it was a very good summary of what you were saying. So let's stick to that process.

Originally Posted By: voxpops
[It would suggest that an acoustic with an "infinite" number of steps available would be impossible to play! The feedback would overwhelm the player because they would become unable to strike anything at the desired level.

It suggests no such thing. You can't process the feedback with infinite resolution. You don't blow a mental transistor because your mind or muscle memory can no longer distinguish one small change in volume or timbre from another. You simply process things to the level you are capable, and then use that feedback to drive your motor skills to the level they are capable.

Originally Posted By: voxpops
No, a player almost subconsciously molds his playing to the input he is receiving. The finer the resolution available, the better he is able to play.

No, none of us have infinite feedback sensor resolution or infinite motor skills resolution. Once you abandon that concept I think this entire subject becomes easier to analyze.
_________________________
Macy

CVP-409GP, Vintage D, Ivory II GP's & American Concert D, True Keys American D, Ravenscroft 275, Garritan Authorized Steinway, Alicia's Keys, EWQL Pianos, MainStage, iPad/forScore/PageFlip Cicada, Custom Mac MIDI/Audio Software Design, Macs Everywhere

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#1885314 - 04/23/12 09:31 PM Re: Sampled VS Modelled Pianos ??? [Re: musicmad]
sullivang Online   blank
2000 Post Club Member

Registered: 07/05/09
Posts: 2191
Loc: Sydney, Australia
@Macy,
With respect, after having read your reply to Voxpops, I still don't think you have fully understood what I have been trying to say.

Adding the noise to the MIDI velocity is simply to restore the randomness that the quantisation has removed. For example, in your example where you have quantised the player's velocity to 10000 steps, it may be that the steps which you have thrown away that fall inbetween those 10000 steps are important. There is no way to invoke those intermediate steps any more - they have been stolen away from the instrument. The player cannot play any given one of those intermediate steps on demand, however the player may notice the complete absence of those steps.

There are two issues here:
1. How many steps does it take to sample a human's intended velocity with sufficient accuracy?
2. How many usable/interesting steps is the instrument able to reproduce?

These two issues must be treated seperately.

Greg.

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