Re: [Csnd] unexpected integ offset

Date	2011-09-25 21:04
From	"Partev Barr Sarkissian"
Subject	Re: [Csnd] unexpected integ offset
	Victor, Was looking at the opcodes in the online manual, dcblock2 looks good for this application? -partev =============================================================== --- Victor.Lazzarini@nuim.ie wrote: From: Victor Lazzarini To: csound@lists.bath.ac.uk Subject: Re: [Csnd] unexpected integ offset Date: Sun, 25 Sep 2011 10:24:55 +0100 yes, there is a DC and that is what the code tries to remove. But I would use a DC blocker instead. Victor On 25 Sep 2011, at 04:35, Partev Barr Sarkissian wrote: > Victor, > > I think that makes sense. Correct me if I'm wrong, but when you > mathemtically break down a signal into it's components, with a > number of Low-Pass filter types, isn't there a DC component in > there? That Split Side-Band paper you did (in JAES, September > 2008 was it?), wasn't there a DC component in the Taylor Series > Expansion you did? > > > Regards, cheers, > -Partev > > > ================================================================ > > > --- Victor.Lazzarini@nuim.ie wrote: > > From: Victor.Lazzarini@nuim.ie > To: csound@lists.bath.ac.uk > Subject: Re: [Csnd] unexpected integ offset > Date: Wed, 21 Sep 2011 20:12:18 +0100 > > The integrtator is an IIR LP filter, so it will produce a signal with > a certain amount of DC as it has a pole at 0Hz. The code assumes this > to be about 0.5 and tries to remove it. I'd say a more robust > approach is to use a DC blocker. > Victor > ----- Original Message ----- > From: ebmtranceboy > Date: Wednesday, September 21, 2011 6:37 pm > Subject: [Csnd] unexpected integ offset > To: csound@lists.bath.ac.uk >> Hi all, >> Sorry in advance if this is not the right place to ask this kind of >> question. >> I'm trying to understand the following instrument and I'm >> puzzled by the >> "asaw = asawdc - .5" line >> >> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; >> instr 1; band limited sawtooth wave >> ; coded by Josep M Comajuncosas / jan98 >> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; >> >> iamp >> = 10000; intended max. amplitude >> kenv linen 1, .2,p3,.2; volume envelope >> kfreq >> = cpspch(p4) >> ibound = sr/4; >> set it to sr/2 for true BL square wave >> apulse buzz 1, kfreq, ibound/kfreq, 1 >> asawdc integ apulse >> asaw >> = asawdc - .5 >> out asawdciampkenv >> endin >> >> Indeed, if the fundamental period is 2pi and N the number of > required >> harmonics (ibound/kfreq in instr 1), buzz opcode provides a >> signal (assumely >> continuous) >> >> b(t) = (sum { cos(kt), k = 1.. > N}) / N >> >> so, by integration, >> >> saw(t) = integ [b(u)du, u = 0..t] >> saw(t) = (sum { sin(kt) / k, k = 1.. > N}) / N >> >> which is precisely the reconstruction of the signal whose Fourier >> coefficients are (N times smaller than) (1,1/2,1/3,...,1/N) that >> is just the >> asaw signal we're trying to build and I don't understand where >> the 1/2 >> offset comes from. >> >> Is it a numerical (discrete signal) consequence ? If so, why >> this 1/2 >> coefficient doesn't depend of N (setting ibound to sr/2 for >> example still >> requires the offset set to 1/2 to get the asaw expected). >> >> Help me with my maths please! >> >> >> >> -- >> View this message in context: >> http://csound.1045644.n5.nabble.com/unexpected-integ-offset- >> tp4827197p4827197.htmlSent from the Csound - General mailing >> list archive at Nabble.com. >> >> >> Send bugs reports to the Sourceforge bug tracker >> > https://sourceforge.net/tracker/?group_id=81968&atid=564599 >> Discussions of bugs and features can be posted here >> To unsubscribe, send email sympa@lists.bath.ac.uk with body >> "unsubscribe csound" >> > Dr Victor Lazzarini, Senior Lecturer, Dept. of Music, > National University of Ireland, Maynooth > > > > > _____________________________________________________________ > Netscape. Just the Net You Need. > > > Send bugs reports to the Sourceforge bug tracker > https://sourceforge.net/tracker/?group_id=81968&atid=564599 > Discussions of bugs and features can be posted here > To unsubscribe, send email sympa@lists.bath.ac.uk with body > "unsubscribe csound" > 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 the Sourceforge bug tracker https://sourceforge.net/tracker/?group_id=81968&atid=564599 Discussions of bugs and features can be posted here To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe csound" _____________________________________________________________ Netscape. Just the Net You Need. Send bugs reports to the Sourceforge bug tracker https://sourceforge.net/tracker/?group_id=81968&atid=564599 Discussions of bugs and features can be posted here To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe csound"

Date	2011-09-25 21:11
From	Victor Lazzarini
Subject	Re: [Csnd] unexpected integ offset
	I guess both dcblock and dcblock would do the job. Victor On 25 Sep 2011, at 21:04, Partev Barr Sarkissian wrote: > Victor, > > Was looking at the opcodes in the online manual, dcblock2 looks > good for this application? > > > -partev > > > =============================================================== > > > > --- Victor.Lazzarini@nuim.ie wrote: > > From: Victor Lazzarini > To: csound@lists.bath.ac.uk > Subject: Re: [Csnd] unexpected integ offset > Date: Sun, 25 Sep 2011 10:24:55 +0100 > > yes, there is a DC and that is what the code tries to remove. But I > would use a DC blocker instead. > > Victor > On 25 Sep 2011, at 04:35, Partev Barr Sarkissian wrote: > >> Victor, >> >> I think that makes sense. Correct me if I'm wrong, but when you >> mathemtically break down a signal into it's components, with a >> number of Low-Pass filter types, isn't there a DC component in >> there? That Split Side-Band paper you did (in JAES, September >> 2008 was it?), wasn't there a DC component in the Taylor Series >> Expansion you did? >> >> >> Regards, cheers, >> -Partev >> >> >> ================================================================ >> >> >> --- Victor.Lazzarini@nuim.ie wrote: >> >> From: Victor.Lazzarini@nuim.ie >> To: csound@lists.bath.ac.uk >> Subject: Re: [Csnd] unexpected integ offset >> Date: Wed, 21 Sep 2011 20:12:18 +0100 >> >> The integrtator is an IIR LP filter, so it will produce a signal with >> a certain amount of DC as it has a pole at 0Hz. The code assumes this >> to be about 0.5 and tries to remove it. I'd say a more robust >> approach is to use a DC blocker. >> Victor >> ----- Original Message ----- >> From: ebmtranceboy >> Date: Wednesday, September 21, 2011 6:37 pm >> Subject: [Csnd] unexpected integ offset >> To: csound@lists.bath.ac.uk >>> Hi all, >>> Sorry in advance if this is not the right place to ask this kind of >>> question. >>> I'm trying to understand the following instrument and I'm >>> puzzled by the >>> "asaw = asawdc - .5" line >>> >>> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; >>> instr 1; band limited sawtooth wave >>> ; coded by Josep M Comajuncosas / jan98 >>> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; >>> >>> iamp >>> = 10000; intended max. amplitude >>> kenv linen 1, .2,p3,.2; volume envelope >>> kfreq >>> = cpspch(p4) >>> ibound = sr/4; >>> set it to sr/2 for true BL square wave >>> apulse buzz 1, kfreq, ibound/kfreq, 1 >>> asawdc integ apulse >>> asaw >>> = asawdc - .5 >>> out asawdciampkenv >>> endin >>> >>> Indeed, if the fundamental period is 2pi and N the number of >> required >>> harmonics (ibound/kfreq in instr 1), buzz opcode provides a >>> signal (assumely >>> continuous) >>> >>> b(t) = (sum { cos(kt), k = 1.. >> N}) / N >>> >>> so, by integration, >>> >>> saw(t) = integ [b(u)du, u = 0..t] >>> saw(t) = (sum { sin(kt) / k, k = 1.. >> N}) / N >>> >>> which is precisely the reconstruction of the signal whose Fourier >>> coefficients are (N times smaller than) (1,1/2,1/3,...,1/N) that >>> is just the >>> asaw signal we're trying to build and I don't understand where >>> the 1/2 >>> offset comes from. >>> >>> Is it a numerical (discrete signal) consequence ? If so, why >>> this 1/2 >>> coefficient doesn't depend of N (setting ibound to sr/2 for >>> example still >>> requires the offset set to 1/2 to get the asaw expected). >>> >>> Help me with my maths please! >>> >>> >>> >>> -- >>> View this message in context: >>> http://csound.1045644.n5.nabble.com/unexpected-integ-offset- >>> tp4827197p4827197.htmlSent from the Csound - General mailing >>> list archive at Nabble.com. >>> >>> >>> Send bugs reports to the Sourceforge bug tracker >>> >> https://sourceforge.net/tracker/?group_id=81968&atid=564599 >>> Discussions of bugs and features can be posted here >>> To unsubscribe, send email sympa@lists.bath.ac.uk with body >>> "unsubscribe csound" >>> >> Dr Victor Lazzarini, Senior Lecturer, Dept. of Music, >> National University of Ireland, Maynooth >> >> >> >> >> _____________________________________________________________ >> Netscape. Just the Net You Need. >> >> >> Send bugs reports to the Sourceforge bug tracker >> https://sourceforge.net/tracker/?group_id=81968&atid=564599 >> Discussions of bugs and features can be posted here >> To unsubscribe, send email sympa@lists.bath.ac.uk with body >> "unsubscribe csound" >> > > 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 the Sourceforge bug tracker > https://sourceforge.net/tracker/?group_id=81968&atid=564599 > Discussions of bugs and features can be posted here > To unsubscribe, send email sympa@lists.bath.ac.uk with body > "unsubscribe csound" > > > > > > _____________________________________________________________ > Netscape. Just the Net You Need. > > > Send bugs reports to the Sourceforge bug tracker > https://sourceforge.net/tracker/?group_id=81968&atid=564599 > Discussions of bugs and features can be posted here > To unsubscribe, send email sympa@lists.bath.ac.uk with body > "unsubscribe csound" > 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 the Sourceforge bug tracker https://sourceforge.net/tracker/?group_id=81968&atid=564599 Discussions of bugs and features can be posted here To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe csound"