added panning envelopes
refactored envelopes. no idea if the final panning is right, though. need to do some tests vs FT2.
This commit is contained in:
Andy Sloane
parent
741efc0f25
commit
94d378d4ce
2 changed files with 110 additions and 45 deletions
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@ -5,7 +5,8 @@
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<body>
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<pre>
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todo:
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- pan envelopes
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- instrument fadeout
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- pingpong loops
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- volume effects
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- 8x
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- others?
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152
xm.js
152
xm.js
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@ -46,22 +46,6 @@ var channelinfo = [];
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var instruments = [];
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var tempo = 4;
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function GetEnvelope(env, ticks) {
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// TODO: optimize, maybe
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var y0;
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for (var i = 0; i < env.length; i += 2) {
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y0 = env[i+1];
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if (ticks < env[i]) {
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var x0 = env[i-2];
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var y0 = env[i-1];
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var dx = env[i] - x0;
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var dy = env[i+1] - y0;
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return y0 + (ticks - x0) * dy / dx;
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}
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}
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return y0;
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}
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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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@ -178,6 +162,8 @@ function next_row() {
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// alone
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ch.envtick = 0;
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ch.release = 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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}
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}
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@ -186,6 +172,8 @@ function next_row() {
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ch.release = 0;
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ch.envtick = 0;
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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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}
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}
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@ -200,6 +188,59 @@ function next_row() {
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pat.innerHTML = patdisplay.join("\n");
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}
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function Envelope(points, type, sustain, loopstart, loopend) {
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this.points = points;
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this.type = type;
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this.sustain = sustain;
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this.loopstart = loopstart;
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this.loopend = loopend;
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}
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Envelope.prototype.Get = function(ticks) {
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// TODO: optimize follower with ptr
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// or even do binary search here
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var y0;
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var env = this.points;
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for (var i = 0; i < env.length; i += 2) {
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y0 = env[i+1];
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if (ticks < env[i]) {
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var x0 = env[i-2];
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var y0 = env[i-1];
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var dx = env[i] - x0;
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var dy = env[i+1] - y0;
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return y0 + (ticks - x0) * dy / dx;
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}
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}
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return y0;
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}
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function EnvelopeFollower(env) {
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this.env = env;
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this.tick = 0;
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}
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EnvelopeFollower.prototype.Tick = function(release) {
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if (this.env === undefined) {
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return 64;
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}
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var value = this.env.Get(this.tick);
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if (this.env.type & 1) { // sustain?
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// if we're sustaining a note, stop advancing the tick counter
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if (!release &&
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this.tick >= this.env.points[this.env.sustain*2]) {
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return this.env.points[this.env.sustain*2 + 1];
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}
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}
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this.tick++;
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if (this.env.type & 2) { // envelope loop?
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if (!release &&
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this.tick > this.env.loopend) {
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this.tick -= this.env.loopend - this.env.loopstart;
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}
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}
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return value;
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}
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function next_tick() {
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cur_tick++;
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if (cur_tick >= tempo) {
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@ -213,20 +254,8 @@ function next_tick() {
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ch.effectfn(ch);
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}
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if (inst === undefined) continue;
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if (inst.env_vol !== undefined) {
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ch.env_vol = GetEnvelope(inst.env_vol, ch.envtick);
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if (inst.env_vol_type & 2) { // sustain loop?
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// if we're sustaining a note, leave env_vol alone
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if (ch.release == 0) {
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if (ch.envtick >= inst.env_vol[inst.env_vol_sustain*2]) {
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continue;
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}
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}
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}
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ch.envtick++;
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} else {
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ch.env_vol = 64;
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}
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ch.volE = ch.env_vol.Tick(ch.release);
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ch.panE = ch.env_pan.Tick(ch.release);
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}
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}
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@ -263,10 +292,11 @@ function audio_cb(e) {
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sample_end = looplen + inst.loop;
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}
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var samplen = inst.len;
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var env_vol = ch.env_vol / 64.0;
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var p = ch.pan - 128;
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var volL = env_vol * (128 - p) * ch.vol / 8192.0;
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var volR = env_vol * (128 + p) * ch.vol / 8192.0;
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var volE = ch.volE / 64.0;
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var panE = (ch.panE - 32);
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var p = panE + ch.pan - 128;
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var volL = volE * (128 - p) * ch.vol / 8192.0;
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var volR = volE * (128 + p) * ch.vol / 8192.0;
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if (volL < 0) volL = 0;
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if (volR < 0) volR = 0;
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if (volR == 0 && volL == 0)
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@ -277,8 +307,17 @@ function audio_cb(e) {
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for (var i = offset; i < offset+tickduration; i++) {
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if (ch.mute) break;
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var s = samp[k|0];
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var si = ch.filter[0] * (s + ch.filterstate[0]) + ch.filter[1]*ch.filterstate[1] + ch.filter[2]*ch.filterstate[2];
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ch.filterstate[2] = ch.filterstate[1]; ch.filterstate[1] = si; ch.filterstate[0] = s;
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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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// brick wall filter, but this is much simpler computationally and
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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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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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// one-pole filter to avoid pops and clicks when volume changes.
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ch.vL = popfilter_alpha * ch.vL + (1 - popfilter_alpha) * (volL + ch.vLprev) * 0.5;
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ch.vR = popfilter_alpha * ch.vR + (1 - popfilter_alpha) * (volR + ch.vRprev) * 0.5;
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ch.vLprev = volL;
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@ -292,12 +331,19 @@ function audio_cb(e) {
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} else {
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// kill sample
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ch.inst = undefined;
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// ramp down with the pop filter
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// ramp down to zero with the pop filter
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// if the sample ends right before the end of the tick (or the end
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// of the buffer), we could still get a pop but *usually* it's
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// hidden behind other changes in the tick... there's only so much
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// we can do here, anyway. i guess we could hold the dc offset...
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var rampend = Math.min(offset+tickduration, i+200);
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for (i++; i < rampend; i++) {
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// fill rest of buffer with filtered silence to avoid a pop
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var si = popfilter[0] * (ch.filterstate[0]) + popfilter[1]*ch.filterstate[1] + popfilter[2]*ch.filterstate[2];
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ch.filterstate[2] = ch.filterstate[1]; ch.filterstate[1] = si; ch.filterstate[0] = 0;
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var si = popfilter[0] * (ch.filterstate[0]) +
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popfilter[1]*ch.filterstate[1] +
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popfilter[2]*ch.filterstate[2];
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ch.filterstate[2] = ch.filterstate[1];
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ch.filterstate[1] = si; ch.filterstate[0] = 0;
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dataL[i] += ch.vL * si;
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dataR[i] += ch.vR * si;
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}
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@ -568,10 +614,19 @@ function playXM(arrayBuf) {
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var env_vol_sustain = dv.getUint8(idx+227);
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var env_vol_loop_start = dv.getUint8(idx+228);
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var env_vol_loop_end = dv.getUint8(idx+229);
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var env_npan = dv.getUint8(idx+226);
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var env_pan_type = dv.getUint8(idx+234);
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var env_pan_sustain = dv.getUint8(idx+230);
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var env_pan_loop_start = dv.getUint8(idx+231);
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var env_pan_loop_end = dv.getUint8(idx+232);
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env_vol = [];
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for (var j = 0; j < env_nvol*2; j++) {
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env_vol.push(dv.getUint16(idx+129+j*2, true));
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}
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env_pan = [];
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for (var j = 0; j < env_npan*2; j++) {
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env_pan.push(dv.getUint16(idx+177+j*2, true));
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}
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if (nsamp > 0) {
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// FIXME: ignoring keymaps for now and assuming 1 sample / instrument
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// var keymap = getarray(dv, idx+0x21);
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@ -607,11 +662,20 @@ function playXM(arrayBuf) {
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'sampledata': ConvertSample(new Uint8Array(arrayBuf, sampleoffset, samplen), samptype & 4),
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};
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if (env_vol_type) {
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inst.env_vol = env_vol;
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inst.env_vol_type = env_vol_type;
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inst.env_vol_sustain = env_vol_sustain;
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inst.env_vol_loop_start = env_vol_loop_start;
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inst.env_vol_loop_end = env_vol_loop_end;
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inst.env_vol = new Envelope(
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env_vol,
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env_vol_type,
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env_vol_sustain,
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env_vol_loop_start,
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env_vol_loop_end);
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}
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if (env_pan_type) {
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inst.env_pan = new Envelope(
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env_pan,
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env_pan_type,
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env_pan_sustain,
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env_pan_loop_start,
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env_pan_loop_end);
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}
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instruments.push(inst);
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} else {
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