[Csnd] how to avoid aliasing in fm-modulation

[Csnd] how to avoid aliasing in fm-modulation

Date	2014-03-30 17:12
From	Stefan Thomas
Subject	[Csnd] how to avoid aliasing in fm-modulation
	Dear community, I have a problem with the following file. When I play in the highest octave of the piano, I get aliasing sounds. Off course, if the index is nearly 0, the aliasing diappears, but the sound looses its character. Is there another possibility to suppress the aliasing sound? Here is my snippet: <CsoundSynthesizer> <CsOptions> -odac -Ma -m0d </CsOptions> ; ============================================== <CsInstruments> sr = 44100 ksmps = 100 nchnls = 2 0dbfs = 1 gisine ftgen 0,0,2^13, 10, 1 alwayson 1 instr 1 iamp ampmidi 0.1 icps cpsmidi icps = icps3.64 ; key 69 sounds as "normal" a icar = 1 imod = 1.27475486 aenv linsegr 0,0.01,1,5,0,0.1,0 kndxenv expseg 1,0.1,0.75,5,0.5 index = 1 asig foscil aenviamp, icps, icar, imod, index*kndxenv, gisine outs asig, asig endin </CsInstruments> ; ============================================== <CsScore> </CsScore> </CsoundSynthesizer>

Date	2014-03-30 17:40
From	Hlöðver Sigurðsson
Subject	Re: [Csnd] how to avoid aliasing in fm-modulation
	Just an idea. To turn off the index for high notes instr 1 iamp ampmidi 0.1 icps cpsmidi icps = icps3.64 ; key 69 sounds as "normal" a icar = 1 imod = 1.27475486 aenv linsegr 0,0.01,1,5,0,0.1,0 kndxenv expseg 1,0.1,0.75,5,0.5 if (icps > 10000) then index = 0 else index = 1 endif asig foscil aenviamp, icps, icar, imod, indexkndxenv, gisine outs asig, asig endin 2014-03-30 16:12 GMT+00:00 Stefan Thomas <kontrapunktstefan@gmail.com>: Dear community, I have a problem with the following file. When I play in the highest octave of the piano, I get aliasing sounds. Off course, if the index is nearly 0, the aliasing diappears, but the sound looses its character. Is there another possibility to suppress the aliasing sound? Here is my snippet: <CsoundSynthesizer> <CsOptions> -odac -Ma -m0d </CsOptions> ; ============================================== <CsInstruments> sr = 44100 ksmps = 100 nchnls = 2 0dbfs = 1 gisine ftgen 0,0,2^13, 10, 1 alwayson 1 instr 1 iamp ampmidi 0.1 icps cpsmidi icps = icps3.64 ; key 69 sounds as "normal" a icar = 1 imod = 1.27475486 aenv linsegr 0,0.01,1,5,0,0.1,0 kndxenv expseg 1,0.1,0.75,5,0.5 index = 1 asig foscil aenviamp, icps, icar, imod, indexkndxenv, gisine outs asig, asig endin </CsInstruments> ; ============================================== <CsScore> </CsScore> </CsoundSynthesizer> -- Hlöðver Sigurðsson

Date	2014-03-30 19:38
From	Stefan Thomas
Subject	Re: [Csnd] how to avoid aliasing in fm-modulation
	Yes, that could be an idea, but than I will get another basis pitch (with this ratio between carrier and modulator the perceived pitch is lower). 2014-03-30 18:40 GMT+02:00 Hlöðver Sigurðsson <hlolli@gmail.com>: Just an idea. To turn off the index for high notes instr 1 iamp ampmidi 0.1 icps cpsmidi icps = icps3.64 ; key 69 sounds as "normal" a icar = 1 imod = 1.27475486 aenv linsegr 0,0.01,1,5,0,0.1,0 kndxenv expseg 1,0.1,0.75,5,0.5 if (icps > 10000) then index = 0 else index = 1 endif asig foscil aenviamp, icps, icar, imod, indexkndxenv, gisine outs asig, asig endin 2014-03-30 16:12 GMT+00:00 Stefan Thomas <kontrapunktstefan@gmail.com>: Dear community, I have a problem with the following file. When I play in the highest octave of the piano, I get aliasing sounds. Off course, if the index is nearly 0, the aliasing diappears, but the sound looses its character. Is there another possibility to suppress the aliasing sound? Here is my snippet: <CsoundSynthesizer> <CsOptions> -odac -Ma -m0d </CsOptions> ; ============================================== <CsInstruments> sr = 44100 ksmps = 100 nchnls = 2 0dbfs = 1 gisine ftgen 0,0,2^13, 10, 1 alwayson 1 instr 1 iamp ampmidi 0.1 icps cpsmidi icps = icps3.64 ; key 69 sounds as "normal" a icar = 1 imod = 1.27475486 aenv linsegr 0,0.01,1,5,0,0.1,0 kndxenv expseg 1,0.1,0.75,5,0.5 index = 1 asig foscil aenviamp, icps, icar, imod, indexkndxenv, gisine outs asig, asig endin </CsInstruments> ; ============================================== <CsScore> </CsScore> </CsoundSynthesizer> -- Hlöðver Sigurðsson

Date	2014-03-31 19:04
From	David Mooney
Subject	Re: [Csnd] how to avoid aliasing in fm-modulation
	You could also use a low pass filter. Stack a few butterlp filters somewhat below the Nyquist limit for the sample rate you are using: a1 butlp asig,20000 a2 butlp a1,20000 aout butlp a2,20000 Stacking them hardens the cutoff. --David Mooney On Sun, Mar 30, 2014 at 12:12 PM, Stefan Thomas <kontrapunktstefan@gmail.com> wrote: Dear community, I have a problem with the following file. When I play in the highest octave of the piano, I get aliasing sounds. Off course, if the index is nearly 0, the aliasing diappears, but the sound looses its character. Is there another possibility to suppress the aliasing sound? Here is my snippet: <CsoundSynthesizer> <CsOptions> -odac -Ma -m0d </CsOptions> ; ============================================== <CsInstruments> sr = 44100 ksmps = 100 nchnls = 2 0dbfs = 1 gisine ftgen 0,0,2^13, 10, 1 alwayson 1 instr 1 iamp ampmidi 0.1 icps cpsmidi icps = icps3.64 ; key 69 sounds as "normal" a icar = 1 imod = 1.27475486 aenv linsegr 0,0.01,1,5,0,0.1,0 kndxenv expseg 1,0.1,0.75,5,0.5 index = 1 asig foscil aenviamp, icps, icar, imod, index*kndxenv, gisine outs asig, asig endin </CsInstruments> ; ============================================== <CsScore> </CsScore> </CsoundSynthesizer> -- Opaque Melodies http://opaquemelodies.com

Date	2014-03-31 19:05
From	Justin Smith
Subject	Re: [Csnd] how to avoid aliasing in fm-modulation
	Frequency aliasing places higher frequencies into lower ones. You would need to also up the sr in order for filtering to really work. On Mon, Mar 31, 2014 at 11:04 AM, David Mooney <dmooney023@gmail.com> wrote: You could also use a low pass filter. Stack a few butterlp filters somewhat below the Nyquist limit for the sample rate you are using: a1 butlp asig,20000 a2 butlp a1,20000 aout butlp a2,20000 Stacking them hardens the cutoff. --David Mooney On Sun, Mar 30, 2014 at 12:12 PM, Stefan Thomas <kontrapunktstefan@gmail.com> wrote: Dear community, I have a problem with the following file. When I play in the highest octave of the piano, I get aliasing sounds. Off course, if the index is nearly 0, the aliasing diappears, but the sound looses its character. Is there another possibility to suppress the aliasing sound? Here is my snippet: <CsoundSynthesizer> <CsOptions> -odac -Ma -m0d </CsOptions> ; ============================================== <CsInstruments> sr = 44100 ksmps = 100 nchnls = 2 0dbfs = 1 gisine ftgen 0,0,2^13, 10, 1 alwayson 1 instr 1 iamp ampmidi 0.1 icps cpsmidi icps = icps3.64 ; key 69 sounds as "normal" a icar = 1 imod = 1.27475486 aenv linsegr 0,0.01,1,5,0,0.1,0 kndxenv expseg 1,0.1,0.75,5,0.5 index = 1 asig foscil aenviamp, icps, icar, imod, index*kndxenv, gisine outs asig, asig endin </CsInstruments> ; ============================================== <CsScore> </CsScore> </CsoundSynthesizer> -- Opaque Melodies http://opaquemelodies.com

Date	2014-03-31 19:06
From	Victor Lazzarini
Subject	Re: [Csnd] how to avoid aliasing in fm-modulation
	If the aliasing is in the generated signal, filtering like that will not help. On 31 Mar 2014, at 19:04, David Mooney wrote: > You could also use a low pass filter. Stack a few butterlp filters somewhat below the Nyquist limit for the sample rate you are using: > > a1 butlp asig,20000 > a2 butlp a1,20000 > aout butlp a2,20000 > > Stacking them hardens the cutoff. > > --David Mooney > > > On Sun, Mar 30, 2014 at 12:12 PM, Stefan Thomas wrote: > Dear community, > I have a problem with the following file. > When I play in the highest octave of the piano, I get aliasing sounds. Off course, if the index is nearly 0, the aliasing diappears, but the sound looses its character. Is there another possibility to suppress the aliasing sound? > Here is my snippet: > > > -odac -Ma -m0d > > > ; ============================================== > > > sr = 44100 > ksmps = 100 > nchnls = 2 > 0dbfs = 1 > gisine ftgen 0,0,2^13, 10, 1 > alwayson 1 > instr 1 > iamp ampmidi 0.1 > icps cpsmidi > icps = icps3.64 ; key 69 sounds as "normal" a > icar = 1 > imod = 1.27475486 > aenv linsegr 0,0.01,1,5,0,0.1,0 > kndxenv expseg 1,0.1,0.75,5,0.5 > index = 1 > asig foscil aenviamp, icps, icar, imod, index*kndxenv, gisine > outs asig, asig > endin > > > ; ============================================== > > > > > > > > > > -- > Opaque Melodies > http://opaquemelodies.com Dr Victor Lazzarini Senior Lecturer Dept. of Music NUI Maynooth Ireland tel.: +353 1 708 3545 Victor dot Lazzarini AT nuim dot ie Send bugs reports to https://github.com/csound/csound/issues Discussions of bugs and features can be posted here To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe csound"

Date	2014-04-01 09:07
From	Stefan Thomas
Subject	Re: [Csnd] how to avoid aliasing in fm-modulation
	Dear friends, I found out that changing the ratio between modulator and carrier will result in the same spectrum but with desired basis-pitch. The ratio is 4.64010769 (I've calculated this with the software scala). 2014-03-31 20:06 GMT+02:00 Victor Lazzarini <Victor.Lazzarini@nuim.ie>: If the aliasing is in the generated signal, filtering like that will not help. On 31 Mar 2014, at 19:04, David Mooney wrote: > You could also use a low pass filter. Stack a few butterlp filters somewhat below the Nyquist limit for the sample rate you are using: > > a1 butlp asig,20000 > a2 butlp a1,20000 > aout butlp a2,20000 > > Stacking them hardens the cutoff. > > --David Mooney > > > On Sun, Mar 30, 2014 at 12:12 PM, Stefan Thomas <kontrapunktstefan@gmail.com> wrote: > Dear community, > I have a problem with the following file. > When I play in the highest octave of the piano, I get aliasing sounds. Off course, if the index is nearly 0, the aliasing diappears, but the sound looses its character. Is there another possibility to suppress the aliasing sound? > Here is my snippet: > <CsoundSynthesizer> > <CsOptions> > -odac -Ma -m0d > </CsOptions> > > ; ============================================== > <CsInstruments> > > sr = 44100 > ksmps = 100 > nchnls = 2 > 0dbfs = 1 > gisine ftgen 0,0,2^13, 10, 1 > alwayson 1 > instr 1 > iamp ampmidi 0.1 > icps cpsmidi > icps = icps3.64 ; key 69 sounds as "normal" a > icar = 1 > imod = 1.27475486 > aenv linsegr 0,0.01,1,5,0,0.1,0 > kndxenv expseg 1,0.1,0.75,5,0.5 > index = 1 > asig foscil aenviamp, icps, icar, imod, index*kndxenv, gisine > outs asig, asig > endin > > </CsInstruments> > ; ============================================== > <CsScore> > </CsScore> > </CsoundSynthesizer> > > > > > > > -- > Opaque Melodies > http://opaquemelodies.com Dr Victor Lazzarini Senior Lecturer Dept. of Music NUI Maynooth Ireland tel.: +353 1 708 3545 Victor dot Lazzarini AT nuim dot ie Send bugs reports to https://github.com/csound/csound/issues Discussions of bugs and features can be posted here To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe csound"

Date	2014-04-01 14:44
From	Aidan Collins
Subject	Re: [Csnd] how to avoid aliasing in fm-modulation
	I'm also pretty interested in this topic. I had been experimenting with FM in the past and hadn't really appreciated the aliasing concern. Stefan, could you describe a little more the thought process that lead you to that alternate ratio? Does anyone else have any other interesting ways to address these aliasing in FM synthesis? Is the typical approach to do the math or use your ears to just avoid generating those frequencies, or using a really high sr? Thanks! Aidan On Tue, Apr 1, 2014 at 4:07 AM, Stefan Thomas <kontrapunktstefan@gmail.com> wrote: Dear friends, I found out that changing the ratio between modulator and carrier will result in the same spectrum but with desired basis-pitch. The ratio is 4.64010769 (I've calculated this with the software scala). 2014-03-31 20:06 GMT+02:00 Victor Lazzarini <Victor.Lazzarini@nuim.ie>: If the aliasing is in the generated signal, filtering like that will not help. On 31 Mar 2014, at 19:04, David Mooney wrote: > You could also use a low pass filter. Stack a few butterlp filters somewhat below the Nyquist limit for the sample rate you are using: > > a1 butlp asig,20000 > a2 butlp a1,20000 > aout butlp a2,20000 > > Stacking them hardens the cutoff. > > --David Mooney > > > On Sun, Mar 30, 2014 at 12:12 PM, Stefan Thomas <kontrapunktstefan@gmail.com> wrote: > Dear community, > I have a problem with the following file. > When I play in the highest octave of the piano, I get aliasing sounds. Off course, if the index is nearly 0, the aliasing diappears, but the sound looses its character. Is there another possibility to suppress the aliasing sound? > Here is my snippet: > <CsoundSynthesizer> > <CsOptions> > -odac -Ma -m0d > </CsOptions> > > ; ============================================== > <CsInstruments> > > sr = 44100 > ksmps = 100 > nchnls = 2 > 0dbfs = 1 > gisine ftgen 0,0,2^13, 10, 1 > alwayson 1 > instr 1 > iamp ampmidi 0.1 > icps cpsmidi > icps = icps3.64 ; key 69 sounds as "normal" a > icar = 1 > imod = 1.27475486 > aenv linsegr 0,0.01,1,5,0,0.1,0 > kndxenv expseg 1,0.1,0.75,5,0.5 > index = 1 > asig foscil aenviamp, icps, icar, imod, index*kndxenv, gisine > outs asig, asig > endin > > </CsInstruments> > ; ============================================== > <CsScore> > </CsScore> > </CsoundSynthesizer> > > > > > > > -- > Opaque Melodies > http://opaquemelodies.com Dr Victor Lazzarini Senior Lecturer Dept. of Music NUI Maynooth Ireland tel.: +353 1 708 3545 Victor dot Lazzarini AT nuim dot ie Send bugs reports to https://github.com/csound/csound/issues Discussions of bugs and features can be posted here To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe csound"