http://elists.resynthesize.com Electronic Music Mailing List Archives - musicdsp en-us http://elists.resynthesize.com/musicdsp/2008/05/1948562/ 2008-05-14 09:00:00 http://elists.resynthesize.com/musicdsp/2008/05/1948116/ 2008-05-14 05:33:59 I was also wondering whether it might be possible to store amplitude > data less frequently in either the time or frequency dimension for higher > frequency bins without noticeable degredation in quality.=A0 I was also=20 > considering using ADPCM with uLaw compression to compress both the > amplitudes and frequencies.=A0 This seems the most useful data reduction approach. The first thing=20 that came to mind is fitting breakpoint line envelopes as is often done with additive resynthesis data. You may be able to find a rea]]> http://elists.resynthesize.com/musicdsp/2008/05/1948088/ 2008-05-14 04:26:34 http://elists.resynthesize.com/musicdsp/2008/05/1945590/ 2008-05-10 12:09:58 http://elists.resynthesize.com/musicdsp/2008/05/1945505/ 2008-05-09 05:33:35 http://elists.resynthesize.com/musicdsp/2008/05/1945019/ 2008-05-09 12:59:41 There was a 'pretty good' IIR approximation Hilbert in CSound source > last time I looked (a few years ago). Maybe still in there. > > The CSound Hilbert was a digital emulation of an analog Hilbert which > was published by Bernie Hutchins in his Electronotes magazine long ago. > > It sends the signal thru two legs of cascaded first-order phase > shifters. The 'staggered' FC's of the two phase shifter chains, > resulted in the output of one phase shifter cascade, a pretty good > approximation of 90 degrees shifted against the other phase shifter > cascade ]]> http://elists.resynthesize.com/musicdsp/2008/05/1944829/ 2008-05-08 03:45:43 http://elists.resynthesize.com/musicdsp/2008/05/1944816/ 2008-05-08 03:04:53 >> ----- Original Message ----- >> From: "Charles Henry" >> To: "A discussion list for music-related DSP" >> Subject: Re: [music-dsp] FAQ is BAQ! - frequency shifting. >> Date: Thu, 8 May 2008 14:36:14 -0500 >> >> >> Quick question, here. I have sometimes struggled to create a good RT >> Hilbert transform (I made a couple of pd patches that while appearing >> to be correct on the surface with relevant math behind it, but >> produces horrible phase shifts). How does one make an RT Hilbert >> transform? >> (I can also prov]]> http://elists.resynthesize.com/musicdsp/2008/05/1944808/ 2008-05-08 02:39:55 ----- Original Message ----- > From: "Charles Henry" > To: "A discussion list for music-related DSP" > Subject: Re: [music-dsp] FAQ is BAQ! - frequency shifting. > Date: Thu, 8 May 2008 14:36:14 -0500 >=20 >=20 > Quick question, here. I have sometimes struggled to create a good RT > Hilbert transform (I made a couple of pd patches that while appearing > to be correct on the surface with relevant math behind it, but > produces horrible phase shifts). How does one make an RT Hilbert > transform? > (I can also provide details on my method, if desired.) it's a filter, but a true Hilbe]]> http://elists.resynthesize.com/musicdsp/2008/05/1944743/ 2008-05-08 12:36:14 there is a technical value judgement here ("best, simple[st], [most] efficient, clean[est]") that might not be universally held. another method that is current (even more current because in Weaver's day, they didn't have real-time Hilbert transformers) involves a single "filter" (the Hilbert transformer, i won't count the corresponding delay line as another filter) and two sine/cosine multiply operations. a quick Google search finds this link to illustrate: > > http://www56.homepage.villanova.edu/scott.sawyer/fpga/II_fre]]>