fix vibrato, implement 6xy
This commit is contained in:
Andy Sloane
parent
17123cc5f1
commit
b82a350011
1 changed files with 55 additions and 35 deletions
90
xm.js
90
xm.js
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@ -51,9 +51,11 @@ var tempo = 4;
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// Return 2-pole Butterworth lowpass filter coefficients for
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// center frequncy f_c (relative to sampling frequency)
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function FilterCoeffs(f_c) {
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// if (f_c > 0.5) { // we can't lowpass above the nyquist frequency...
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// return [1, 0, 0];
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// }
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// if (f_c > 0.5) { // we can't lowpass above the nyquist frequency...
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// return [1, 0, 0];
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// }
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// what happens instead is the filter wraps around to an alias frequency,
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// and that also works OK, though it isn't strictly right... FIXME
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var wct = Math.sqrt(2) * Math.PI * f_c;
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var e = Math.exp(-wct);
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var c = e * Math.cos(wct);
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@ -75,11 +77,6 @@ function PeriodForNote(ch, note) {
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return 1920 - note*16 - ch.inst.fine / 8.0;
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}
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function UpdateChannelNote(ch, note) {
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ch.period = PeriodForNote(ch, note);
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UpdateChannelPeriod(ch, ch.period);
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}
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var cur_songpos = -1, cur_pat = -1, cur_row = 64, cur_ticksamp = 0;
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var cur_tick = 6;
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var patdisplay = [];
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@ -183,7 +180,7 @@ function next_row() {
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ch.vibratopos = 0;
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ch.env_vol = new EnvelopeFollower(inst.env_vol);
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ch.env_pan = new EnvelopeFollower(inst.env_pan);
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UpdateChannelNote(ch, note);
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ch.period = PeriodForNote(ch, note);
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}
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}
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var debug = document.getElementById("debug");
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@ -259,12 +256,14 @@ function next_tick() {
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for (var j = 0; j < nchan; j++) {
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var ch = channelinfo[j];
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var inst = ch.inst;
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ch.periodoffset = 0;
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if (ch.effectfn) {
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ch.effectfn(ch);
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}
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if (inst === undefined) continue;
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ch.volE = ch.env_vol.Tick(ch.release, 64);
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ch.panE = ch.env_pan.Tick(ch.release, 32);
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UpdateChannelPeriod(ch, ch.period + ch.periodoffset);
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}
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}
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@ -272,6 +271,10 @@ function next_tick() {
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// already to avoid clicks and pops when samples end.
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function MixSilenceIntoBuf(ch, start, end, dataL, dataR) {
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var s = ch.filterstate[1];
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if (isNaN(s)) {
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console.log("NaN filterstate?", ch.filterstate, ch.filter);
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return;
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}
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for (var i = start; i < end; i++) {
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if (Math.abs(s) < 1.526e-5) // == 1/65536.0
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break;
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@ -281,6 +284,10 @@ function MixSilenceIntoBuf(ch, start, end, dataL, dataR) {
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}
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ch.filterstate[1] = s;
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ch.filterstate[2] = s;
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if (isNaN(s)) {
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console.log("NaN filterstate after adding silence?", ch.filterstate, ch.filter, i);
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return;
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}
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return 0;
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}
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@ -291,7 +298,7 @@ function MixChannelIntoBuf(ch, start, end, dataL, dataR) {
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var looplen = 0;
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// nothing on this channel, just filter the last dc offset back down to zero
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if (inst === undefined || ch.mute) {
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if (inst == undefined || ch.mute) {
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return MixSilenceIntoBuf(ch, start, end, dataL, dataR);
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}
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@ -312,13 +319,31 @@ function MixChannelIntoBuf(ch, start, end, dataL, dataR) {
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if (volR < 0) volR = 0;
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if (volR == 0 && volL == 0)
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return;
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if (isNaN(volR) || isNaN(volL)) {
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console.log("NaN volume!?", volL, volR, colE, panE, ch.vol);
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return;
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}
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var k = ch.off;
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var dk = ch.doff;
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var Vrms = 0;
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for (var i = start; i < end; i++) {
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var s = 0;
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// if ((k|0) != (k-dk)|0)
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s = samp[k|0];
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if (k >= sample_end) { // TODO: implement pingpong looping
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if (loop) {
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k %= looplen;
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} else {
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// kill sample
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ch.inst = undefined;
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// fill rest of buf with filtered dc offset using loop above
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return Vrms + MixSilenceIntoBuf(ch, i+1, end, dataL, dataR);
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}
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}
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var s = samp[k|0];
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// TODO: robustify, then remove these NaN checks from the inner loops
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if (isNaN(s)) {
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console.log("NaN sample idx", samp.length, k|0);
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tempo = 10000;
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break;
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}
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// we low-pass filter here since we are resampling some arbitrary
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// frequency to f_smp; this is an anti-aliasing filter and is
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// implemented as an IIR butterworth filter (usually we'd use an FIR
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@ -326,6 +351,10 @@ function MixChannelIntoBuf(ch, start, end, dataL, dataR) {
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// sounds fine)
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var si = ch.filter[0] * (s + ch.filterstate[0]) +
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ch.filter[1]*ch.filterstate[1] + ch.filter[2]*ch.filterstate[2];
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if (isNaN(si)) {
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console.log("NaN after filter sample idx", samp, k|0, ch.filter, ch.filterstate, s);
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break;
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}
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ch.filterstate[2] = ch.filterstate[1];
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ch.filterstate[1] = si; ch.filterstate[0] = s;
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// we also low-pass filter volume changes with a simple one-zero,
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@ -338,16 +367,6 @@ function MixChannelIntoBuf(ch, start, end, dataL, dataR) {
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dataR[i] += ch.vR * si;
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Vrms += (ch.vL + ch.vR) * si * si;
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k += dk;
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if (k >= sample_end) { // TODO: implement pingpong looping
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if (loop) {
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k -= looplen;
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} else {
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// kill sample
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ch.inst = undefined;
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// fill rest of buf with filtered dc offset using loop above
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return Vrms + MixSilenceIntoBuf(ch, i+1, end, dataL, dataR);
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}
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}
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}
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ch.off = k;
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ch.doff = dk;
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@ -455,10 +474,8 @@ function eff_t0_f(ch, data) { // set tempo
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return;
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} else if(data < 0x20) {
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tempo = data;
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console.log("tempo", tempo);
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} else {
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bpm = data;
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console.log("bpm", bpm);
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}
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}
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@ -471,9 +488,9 @@ var effects_t0 = [ // effect functions on tick 0
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eff_t0_1,
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eff_t0_2,
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eff_t0_3,
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eff_t0_4,
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eff_t0_4, // 4
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eff_unimplemented_t0, // 5
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eff_unimplemented_t0, // 6
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eff_t0_a, // 6, same as A on first tick
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eff_unimplemented_t0, // 7
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eff_unimplemented_t0, // 8
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eff_unimplemented_t0, // 9
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@ -489,21 +506,21 @@ function eff_t1_0(ch) { // arpeggio
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if (ch.effectdata != 0) {
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var arpeggio = [0, ch.effectdata>>4, ch.effectdata&15];
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var note = ch.note + arpeggio[cur_tick % 3];
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UpdateChannelNote(ch, note);
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ch.period = PeriodForNote(ch, note);
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}
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}
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function eff_t1_1(ch) { // pitch slide up
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if (ch.slideupspeed !== undefined) {
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// is this limited? it appears not
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ch.period -= ch.slideupspeed;
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UpdateChannelPeriod(ch, ch.period);
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}
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}
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function eff_t1_2(ch) { // pitch slide down
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if (ch.slidedownspeed !== undefined) {
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ch.period += ch.slidedownspeed;
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UpdateChannelPeriod(ch, ch.period);
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// 1728 is the period for C-1
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ch.period = Math.min(1728, ch.period + ch.slidedownspeed);
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}
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}
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@ -514,17 +531,20 @@ function eff_t1_3(ch) { // portamento
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} else {
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ch.period = Math.min(ch.periodtarget, ch.period + ch.portaspeed);
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}
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UpdateChannelPeriod(ch, ch.period);
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}
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}
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function eff_t1_4(ch) { // vibrato
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ch.period += Math.sin(ch.vibratopos * Math.PI / 32) * ch.vibratodepth;
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UpdateChannelPeriod(ch, ch.period);
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ch.periodoffset = Math.sin(ch.vibratopos * Math.PI / 32) * ch.vibratodepth;
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ch.vibratopos += ch.vibratospeed;
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ch.vibratopos &= 63;
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}
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function eff_t1_6(ch) { // vibrato + volume slide
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eff_t1_a(ch);
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eff_t1_4(ch);
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}
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function eff_t1_a(ch) { // volume slide
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if (ch.volumeslide !== undefined) {
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ch.vol = Math.max(0, Math.min(64, ch.vol + ch.volumeslide));
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@ -539,7 +559,7 @@ var effects_t1 = [ // effect functions on tick 1+
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eff_t1_3,
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eff_t1_4,
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eff_unimplemented, // 5
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eff_unimplemented, // 6
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eff_t1_6,
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eff_unimplemented, // 7
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eff_unimplemented, // 8
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eff_unimplemented, // 9
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