324 lines
8.7 KiB
C
324 lines
8.7 KiB
C
/*
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An experiment in very, very low-spec ColorChord. This technique foregoes
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multiplies.
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Approach 1:
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This approach uses a table, like several colorchord algorithms to only
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process one octave each cycle. It then uses a table to decide how often
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to process each bin. It performs that bin at 4x the bin's sampling
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frequency, in quadrature. So that it performs the +real, +imag, -real,
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-imag operations over each cycle.
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You can observe an overtone at the current bin - 1.5 octaves! This is
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expected, since, it's the inverse of what the DFT of a square wave would
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be.
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That is a minor drawback, but the **major** drawback is that any DC
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offset, OR lower frequencies present when computing higher frequencies will
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induce a significant ground flutter, and make results really inaccurate.
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This will need to be addressed before the algorithm is ready for prime-time.
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NOTE: To explore:
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1) Consider SAMPLE_Q to possibly use all 4 cycles - though this will
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add latency, it will be more "accurate" --> YES! This helps!
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2) Use the cursor to move left and right to sweep tone and up and down
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to change DC-bias. This exhibits this algo's shortcoming.
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TODO: Can we somehow zero out the DC offset?
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DISCOVERY: This approach (octave-step in octave) is very sensitive FSPS
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Theories:
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* If we force all 4 quadrature value to be the same number of
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integration cycles, does that solve it? --> NO! IT GETS MESSY (see Approach 1B)
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*/
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#include <stdio.h>
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#include <math.h>
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#define CNFG_IMPLEMENTATION
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#define CNFGOGL
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#include "rawdraw_sf.h"
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#include "os_generic.h"
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uint32_t EHSVtoHEX( uint8_t hue, uint8_t sat, uint8_t val );
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int lastx = 200;
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int lasty = 1000;
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int main()
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{
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#define FSPS 22100 // Careful, this matters! It is selected to avoid periodic peaks encountered with DC offsets.
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#define OCTAVES 6
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#define BPERO 24
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#define BASE_FREQ 22.5
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#define QUADRATURE_STEP_DENOMINATOR 16384
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// Careful: It makes a lot of sense to explore these relationships.
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#define SAMPLE_Q 4
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#define MAG_IIR 0
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#define RUNNING_IIR 31
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#define COMPLEX_IIR 2
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#define TEST_SAMPLES 256
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int16_t samples[TEST_SAMPLES];
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int i;
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CNFGSetup( "Example App", 1024, 768 );
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// Precomputed Tables
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int8_t whichoctave[2<<OCTAVES];
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for( i = 0; i < (2<<OCTAVES); i++ )
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{
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int j;
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for( j = 0; j < OCTAVES; j++ )
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{
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if( i & (1<<j) ) break;
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}
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if( j == OCTAVES )
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whichoctave[i] = -1;
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else
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whichoctave[i] = OCTAVES - j - 1;
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}
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// Make a running counter to count up by this amount every cycle.
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// If the new number > 2048, then perform a quadrature step.
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int32_t flipdistance[BPERO];
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for( i = 0; i < BPERO; i++ )
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{
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double freq = pow( 2, (double)i / (double)BPERO ) * (BASE_FREQ/2.0);
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double pfreq = pow( 2, OCTAVES ) * freq;
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double spacing = (FSPS / 2) / pfreq / 4;
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flipdistance[i] = QUADRATURE_STEP_DENOMINATOR * spacing;
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// Spacing = "quadrature every X samples"
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//printf( "%f %d\n", spacing, flipdistance[i] );
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}
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// This is for timing. Not accumulated data.
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int32_t quadrature_timing_last[BPERO*OCTAVES] = { 0 };
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uint8_t quadrature_state[BPERO*OCTAVES] = { 0 };
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uint32_t last_accumulated_value[BPERO*OCTAVES*2] = { 0 };
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uint32_t octave_timing[OCTAVES] = { 0 };
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int32_t real_imaginary_running[BPERO*OCTAVES*2] = { 0 };
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uint32_t sample_accumulator = 0;
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int32_t qcount[BPERO*OCTAVES] = { 0 };
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int32_t magsum[BPERO*OCTAVES] = { 0 };
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int frameno = 0;
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double dLT = OGGetAbsoluteTime();
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int samplenoIn = 0;
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int sampleno = 0;
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double ToneOmega = 0;
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int ops;
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while( CNFGHandleInput() )
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{
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CNFGClearFrame();
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frameno++;
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float freq =
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//pow( 2, (frameno%600)/100.0 ) * 25;
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pow( 2, (lastx)/100.0 ) * lastx;
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//101;
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for( i = 0; i < TEST_SAMPLES; i++ )
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{
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samples[i] = lasty/5 + sin( ToneOmega ) * 127;// + (rand()%128)-64;
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ToneOmega += 1 / (double)FSPS * (double)freq * 3.14159 * 2.0;
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}
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char cts[1024];
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sprintf( cts, "%f %d %f", freq, sampleno, ops/(double)sampleno );
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CNFGColor( 0xffffffff );
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CNFGPenX = 2;
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CNFGPenY = 2;
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CNFGDrawText( cts, 2 );
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while( OGGetAbsoluteTime() < dLT + TEST_SAMPLES / (double)FSPS );
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dLT += TEST_SAMPLES / (double)FSPS;
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if( 0 )
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{
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memset( real_imaginary_running, 0, sizeof( real_imaginary_running ) );
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memset( last_accumulated_value, 0, sizeof( last_accumulated_value ) );
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memset( quadrature_timing_last, 0, sizeof( quadrature_timing_last ) );
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memset( quadrature_state, 0, sizeof( quadrature_state ) );
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memset( octave_timing, 0, sizeof( octave_timing ) );
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sample_accumulator = 0;
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}
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for( i = 0; i < TEST_SAMPLES; i++ )
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{
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sample_accumulator += samples[i];
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int octave = whichoctave[(sampleno)&((2<<OCTAVES)-1)];
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sampleno++;
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if( octave < 0 )
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{
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// A "free cycle" this happens every 1/(2^octaves)
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continue;
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}
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#define WATCHBIN 1
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int b;
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int binno = octave * BPERO;
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int ocative_time = octave_timing[octave] += QUADRATURE_STEP_DENOMINATOR;
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for( b = 0; b < BPERO; b++, binno++ )
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{
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ops+=5;
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if( ocative_time - quadrature_timing_last[binno] > 0 )
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{
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ops+=20;
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quadrature_timing_last[binno] += flipdistance[b];
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// This code will get appropriately executed every quadrature update.
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int qstate = quadrature_state[binno] = ( quadrature_state[binno] + 1 ) % 4;
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int last_q_bin = (binno * 2) + ( qstate & 1 );
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int delta = sample_accumulator - last_accumulated_value[last_q_bin];
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last_accumulated_value[last_q_bin] = sample_accumulator;
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// Qstate =
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// (0) = +Cos, (1) = +Sin, (2) = -Cos, (3) = -Sin
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if( qstate & 2 ) delta *= -1;
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// Update real and imaginary components with delta.
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int running = real_imaginary_running[last_q_bin];
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running = running - (running>>RUNNING_IIR) + delta;
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real_imaginary_running[last_q_bin] = running;
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int q = ++qcount[binno];
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if( q == SAMPLE_Q ) // Effective Q factor.
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{
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ops+=20;
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qcount[binno] = 0;
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int newmagR = real_imaginary_running[(binno * 2)];
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int newmagI = real_imaginary_running[(binno * 2)+1];
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real_imaginary_running[(binno * 2)] = newmagR - (newmagR>>COMPLEX_IIR);
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real_imaginary_running[(binno * 2)+1] = newmagI - (newmagI>>COMPLEX_IIR);
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// Super-cheap, non-multiply, approximate complex vector magnitude calculation.
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newmagR = (newmagR<0)?-newmagR:newmagR;
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newmagI = (newmagI<0)?-newmagI:newmagI;
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int newmag =
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//sqrt(newmagR*newmagR + newmagI*newmagI );
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newmagR > newmagI ? newmagR + (newmagI>>1) : newmagI + (newmagR>>1);
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int lastmag = magsum[binno];
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magsum[binno] = lastmag - (lastmag>>MAG_IIR) + newmag;
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}
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}
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}
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}
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int lx, ly;
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for( i = 0; i < BPERO*OCTAVES; i++ )
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{
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CNFGColor( (EHSVtoHEX( (i * 256 / BPERO)&0xff, 255, 255 ) << 8) | 0xff );
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float real = real_imaginary_running[i*2+0];
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float imag = real_imaginary_running[i*2+1];
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float mag = sqrt( real * real + imag * imag );
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mag = (float)magsum[i] * pow( 2, i / (double)BPERO );
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int y = 768 - ((int)(mag / FSPS * 10) >> MAG_IIR);
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if( i ) CNFGTackSegment( i*4, y, lx*4, ly );
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lx = i; ly= y;
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//printf( "%d %d\n", real_imaginary_running[i*2+0], real_imaginary_running[i*2+1] );
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}
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CNFGSwapBuffers();
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}
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}
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void HandleKey( int keycode, int bDown ) { }
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void HandleButton( int x, int y, int button, int bDown ) { }
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void HandleMotion( int x, int y, int mask ) { lastx = x; lasty = y; }
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void HandleDestroy() { }
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uint32_t EHSVtoHEX( uint8_t hue, uint8_t sat, uint8_t val )
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{
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#define SIXTH1 43
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#define SIXTH2 85
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#define SIXTH3 128
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#define SIXTH4 171
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#define SIXTH5 213
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uint16_t or = 0, og = 0, ob = 0;
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hue -= SIXTH1; //Off by 60 degrees.
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//TODO: There are colors that overlap here, consider
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//tweaking this to make the best use of the colorspace.
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if( hue < SIXTH1 ) //Ok: Yellow->Red.
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{
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or = 255;
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og = 255 - ((uint16_t)hue * 255) / (SIXTH1);
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}
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else if( hue < SIXTH2 ) //Ok: Red->Purple
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{
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or = 255;
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ob = (uint16_t)hue*255 / SIXTH1 - 255;
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}
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else if( hue < SIXTH3 ) //Ok: Purple->Blue
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{
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ob = 255;
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or = ((SIXTH3-hue) * 255) / (SIXTH1);
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}
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else if( hue < SIXTH4 ) //Ok: Blue->Cyan
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{
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ob = 255;
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og = (hue - SIXTH3)*255 / SIXTH1;
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}
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else if( hue < SIXTH5 ) //Ok: Cyan->Green.
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{
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og = 255;
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ob = ((SIXTH5-hue)*255) / SIXTH1;
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}
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else //Green->Yellow
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{
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og = 255;
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or = (hue - SIXTH5) * 255 / SIXTH1;
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}
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uint16_t rv = val;
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if( rv > 128 ) rv++;
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uint16_t rs = sat;
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if( rs > 128 ) rs++;
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//or, og, ob range from 0...255 now.
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//Need to apply saturation and value.
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or = (or * val)>>8;
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og = (og * val)>>8;
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ob = (ob * val)>>8;
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//OR..OB == 0..65025
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or = or * rs + 255 * (256-rs);
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og = og * rs + 255 * (256-rs);
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ob = ob * rs + 255 * (256-rs);
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//printf( "__%d %d %d =-> %d\n", or, og, ob, rs );
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or >>= 8;
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og >>= 8;
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ob >>= 8;
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return or | (og<<8) | ((uint32_t)ob<<16);
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}
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