Re: [chuck-users] analog to digital conversion simulation

Sorry... I think I get were the problem is. I am using the same lpf before and after conversion. Using a separate lpf gives better results. One of the problems is that I was passing lpf.last to pulse.next, but pulse is also connected to lpf in the patch. On Oct 12, 2007, at 6:41 PM, eduard wrote:

Hi list,

I'm trying to simulate how adc conversion works using chuck. However, I'm not succeeding as I'm getting too many artifacts in the output sound. Don't know whether i'm getting this wrong from a conceptual point of view or I'm using/setting chuck's UGens wrongly. The patch I use is:

<<<"usage:", "sample_and_hold.ck:output_gain:sr" >>>; adc => OnePole lpf => blackhole; Impulse pulse => lpf => Gain g => dac; .8 => g.gain; if( me.args() ) Std.atof( me.arg(0) ) => g.gain; 1::second/1::samp => float chuck_sr => float new_sr; if( me.args() > 1 ) Std.atof( me.arg(1) ) => new_sr; chuck_sr/new_sr => float next_samp; 1. - new_sr/chuck_sr => lpf.pole; <<>>; <<< next_samp>>>; while(true) { now => time T; next_samp::samp +=> T; lpf.last() => pulse.next; while( now < T ) { 1::samp => now; } }

Then the user should be able to give a certain SR and experience how the input sound would sound when sampled at SR. I'd like to be able to set lpf cutoff frequency at SR/2 and what I thougt of is something like:

1. - new_sr/chuck_sr => lpf.pole;

thus, if user_sr= 44100, then pole=0 and cutoff freq=chuck_sr/2 (should be 22050 if running at 44.1). if user_sr=22050, then pole=0.5 and cutoff freq=chuck_sr/4 (should be 11025 if running at 44.1) etc...

Am I doing this right? On the other hand, a Onepole filter will not suffice to get rid off all frequencies above the cutoff. Is there a way of having a kind of brickwall filter in chuck?

Thanks,

eduard _______________________________________________ chuck-users mailing list chuck-users@lists.cs.princeton.edu https://lists.cs.princeton.edu/mailman/listinfo/chuck-users