Discussion:
[jOrgan-user] Soundfont - Interpolate
BrianS
2017-06-01 06:27:05 UTC
Permalink
What is the meaning and function of the different Interpolate values on the
Fluidsynth propery?

I see the following, and some dispositions, have difference values selected
here:

1. None
2. Linear
3. Order_4'th
4. Order_7'th

Does this have anything to do with latency or audio quality?

Brian.



-----
Regards,

BrianS
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Graham Goode
2017-06-01 07:31:04 UTC
Permalink
Fluidsynth uses interpolation algorithms to resample between samples
in the soundfont and the audio driver. For example, if a sample is
44.1kz and the audio device is playing back at 48kz then interpolation
is used for the conversion. See
https://www.dsprelated.com/freebooks/pasp/Linear_Interpolation.html
for the math.

If your samples are not the same sample rate as your audio device,
then yes - it will have an effect on both latency and quality as the
cpu is running more calculations. Shorter samples (like Bruce Miles'
soundfont as used in the Christie) require less processing, and so use
less resources, etc..

GG
Post by BrianS
What is the meaning and function of the different Interpolate values on the
Fluidsynth propery?
I see the following, and some dispositions, have difference values selected
1. None
2. Linear
3. Order_4'th
4. Order_7'th
Does this have anything to do with latency or audio quality?
Brian.
-----
Regards,
BrianS
--
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BrianS
2017-06-01 11:02:45 UTC
Permalink
Thank you Graham.

Brian.



-----
Regards,

BrianS
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John Beach
2017-06-01 07:39:59 UTC
Permalink
Brian, Apparently, the default setting is Order 4th. But I am going to
check out how jOrgan functions--differently, with each setting, None, Linear
and Order 7th to see if there is a noticeable
difference in quality or function. I'll let you know what I find out.

John Beach

-----Original Message-----
From: BrianS
Sent: Thursday, June 1, 2017 2:27 AM
To: jorgan-***@lists.sourceforge.net
Subject: [jOrgan-user] Soundfont - Interpolate

What is the meaning and function of the different Interpolate values on the
Fluidsynth propery?

I see the following, and some dispositions, have difference values selected
here:

1. None
2. Linear
3. Order_4'th
4. Order_7'th

Does this have anything to do with latency or audio quality?

Brian.



-----
Regards,

BrianS
--
View this message in context:
http://jorgan.999862.n4.nabble.com/Soundfont-Interpolate-tp4665019.html
Sent from the jOrgan - User mailing list archive at Nabble.com.

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John Beach
2017-06-01 09:18:32 UTC
Permalink
Brian, Having no idea of what to expect in terms of relative difference
between the 4 possible settings of Interpolation, I never even thought to
try anything other than the "default" setting (4th Order, figuring that the
programmer knew what was best as a "default" setting. The output quality is
probably dependent on a large number of considerable factors, wave file
sample quality, probably being the
most important of them all. I recently changed my method making soundfonts,
using one wave file for each key of the compass of the keyboard, 61
instances, instead of, in some cases, 3 keys per
wave file, or, in others, one octave per wave file. I think this makes
Fluidsynth tunings more feasible and correct, unless the computer treats
each note pitch as an individual entity without regard to
the fact that the wave file is "stretched" over three adjacent keys, which,
seemingly, would complicate the issue of calculations for parameters.
Anyway, I changed the Interpolation setting from 4th Order
to NONE. I use a Fluidsynth Reverb setting of Room=9, Width=6, Damping=2,
Level=4, the number is the number of green lights lit in the Classic skin of
jOrgan. The sound is a kind of phenomenal, cathedral-acoustic environment.
The articulation is excellent and, especially, the string stops (which I
think are the most difficult wave files from which to obtain convincingly
good quality. So,
I definitely notice a marked improvement in quality using the NONE setting
on Interpolation. As with all observations, mine are subjective. I think
"LINEAR" produces more "ringing" but this may
be a Reverb factor also. Again, there are so many variables affecting sound
quality that it is difficult to make judgments based on those correlative,
interdependent factors.
I have not tried 7th Order, yet, but will and will let you know what it
does.

John


-----Original Message-----
From: BrianS
Sent: Thursday, June 1, 2017 2:27 AM
To: jorgan-***@lists.sourceforge.net
Subject: [jOrgan-user] Soundfont - Interpolate

What is the meaning and function of the different Interpolate values on the
Fluidsynth propery?

I see the following, and some dispositions, have difference values selected
here:

1. None
2. Linear
3. Order_4'th
4. Order_7'th

Does this have anything to do with latency or audio quality?

Brian.



-----
Regards,

BrianS
--
View this message in context:
http://jorgan.999862.n4.nabble.com/Soundfont-Interpolate-tp4665019.html
Sent from the jOrgan - User mailing list archive at Nabble.com.

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BrianS
2017-06-01 10:45:02 UTC
Permalink
Thank you John.

Brian.



-----
Regards,

BrianS
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John Beach
2017-06-01 14:31:10 UTC
Permalink
Brian and Graham, the Audacity Wave Editor program allows for bulk editing
so that all the wave files of a soundfont, for example, can be resampled
from 44.1K to 48K. So, the need for Interpolation is not really necessary.
One thing that might be advantageous to all would be to know what the
optimal factors of the wave files and parameters in Instruments of
soundfonts are, in order for peak efficiency to be attained by a computer.
I realize that recorded pipe sounds, as the "real thing," are duplications
of "original timber." In theory, they can't be improved on.
The consideration should be the least amount of unnecessary or redundant
calculations in processing. So, assuming that an Interpolation setting of
NONE requires no redundant, compensatory processing, which wave file size is
optimal, giving best performance for the least amount of work by the PC?
Since the article considers Linear Interpolation and First Order
Interpolation, which
are presented as being optimal, what is the particular significance or
reasoning for 4th Order or 7th Order Interpolation, (or NONE) as options for
us? Given the particular quality aspects of
wave files, what rate is considered optimal for processing?

John






-----Original Message-----
From: Graham Goode
Sent: Thursday, June 1, 2017 3:31 AM
To: jorgan-***@lists.sourceforge.net
Subject: Re: [jOrgan-user] Soundfont - Interpolate

Fluidsynth uses interpolation algorithms to resample between samples
in the soundfont and the audio driver. For example, if a sample is
44.1kz and the audio device is playing back at 48kz then interpolation
is used for the conversion. See
https://www.dsprelated.com/freebooks/pasp/Linear_Interpolation.html
for the math.

If your samples are not the same sample rate as your audio device,
then yes - it will have an effect on both latency and quality as the
cpu is running more calculations. Shorter samples (like Bruce Miles'
soundfont as used in the Christie) require less processing, and so use
less resources, etc..

GG
Post by BrianS
What is the meaning and function of the different Interpolate values on
the
Fluidsynth propery?
I see the following, and some dispositions, have difference values
selected
1. None
2. Linear
3. Order_4'th
4. Order_7'th
Does this have anything to do with latency or audio quality?
Brian.
-----
Regards,
BrianS
--
http://jorgan.999862.n4.nabble.com/Soundfont-Interpolate-tp4665019.html
Sent from the jOrgan - User mailing list archive at Nabble.com.
------------------------------------------------------------------------------
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