Re: [music-dsp] OSC problem on STM32F4Discovery

2012-04-10 Thread Olli Niemitalo
On Tue, Apr 10, 2012 at 12:06 PM, Julian Schmidt julian_schm...@chipmusik.de wrote: okay, i used exactly RBJs code with 1024 samples tablesize and  I get a  -60 dB spectral distortion floor. That's again what no interpolation would give, so probably there is a bug in the interpolation code,

Re: [music-dsp] OSC problem on STM32F4Discovery

2012-04-10 Thread Olli Niemitalo
On Tue, Apr 10, 2012 at 12:06 PM, Julian Schmidt julian_schm...@chipmusik.de wrote: okay, i used exactly RBJs code with 1024 samples tablesize and  I get a  -60 dB spectral distortion floor. That's again exactly what no interpolation gives, so probably there is a bug in the interpolation code,

Re: [music-dsp] OSC problem on STM32F4Discovery

2012-04-10 Thread Nigel Redmon
Not alone, Emanuel. Clicks, especially 2-3 seconds apart doesn't describe aliasing—and looking at the spectral distortion seems to be a separate issue. Julian, does that still describe the problem you're hearing, after your recent code changes? On Apr 10, 2012, at 6:40 AM, Emanuel Landeholm

Re: [music-dsp] OSC problem on STM32F4Discover

2012-04-10 Thread robert bristow-johnson
now that i think of it, if you're doing linear interpolation and you forget to add that extra repeated point at the end of the wavetable: float wavetable[257]; // one extra point for doing linear interpolation // make sure that wavetable[256] = wavetable[0] you will

Re: [music-dsp] OSC problem on STM32F4Discovery

2012-04-10 Thread Olli Niemitalo
On Tue, Apr 10, 2012 at 6:54 PM, Nigel Redmon earle...@earlevel.com wrote: Clicks, especially 2-3 seconds apart doesn't describe aliasing Here are clicks created by aliasing for you to listen (loudness warning!):

Re: [music-dsp] OSC problem on STM32F4Discovery

2012-04-10 Thread Nigel Redmon
Interesting Olli—though I don't hear that as clicks—maybe they match the OP's interpretation, but not the impression I got when he said there were clicks... On Apr 10, 2012, at 10:06 AM, Olli Niemitalo wrote: On Tue, Apr 10, 2012 at 6:54 PM, Nigel Redmon earle...@earlevel.com wrote: Clicks,

Re: [music-dsp] OSC problem on STM32F4Discover

2012-04-10 Thread Nigel Redmon
Excellent point, Robert. (Another way to avoid it is to mask the index with 0xff, if you want to keep the table 256, but not check for wrap in the mid-interpolation.) On Apr 10, 2012, at 9:05 AM, robert bristow-johnson wrote: now that i think of it, if you're doing linear interpolation and