Demos/jsxm
Watch
1
0
Fork
You've already forked jsxm
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

added panning envelopes

Browse source 
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 2015-10-26 10:41:58 -07:00
commit 94d378d4ce
2 changed files with 110 additions and 45 deletions
Download patch file Download diff file Expand all files Collapse all files

3
index.html
View file

@ -5,7 +5,8 @@
<body> <body>
<pre> <pre>
todo: todo:
- pan envelopes - instrument fadeout
- pingpong loops
- volume effects - volume effects
- 8x - 8x
- others? - others?

152
xm.js
View file

@ -46,22 +46,6 @@ var channelinfo = [];
var instruments = []; var instruments = [];
var tempo = 4; var tempo = 4;
function GetEnvelope(env, ticks) {
// TODO: optimize, maybe
var y0;
for (var i = 0; i < env.length; i += 2) {
y0 = env[i+1];
if (ticks < env[i]) {
var x0 = env[i-2];
var y0 = env[i-1];
var dx = env[i] - x0;
var dy = env[i+1] - y0;
return y0 + (ticks - x0) * dy / dx;
}
}
return y0;
}
// Return 2-pole Butterworth lowpass filter coefficients for // Return 2-pole Butterworth lowpass filter coefficients for
// center frequncy f_c (relative to sampling frequency) // center frequncy f_c (relative to sampling frequency)
function FilterCoeffs(f_c) { function FilterCoeffs(f_c) {
@ -178,6 +162,8 @@ function next_row() {
// alone // alone
ch.envtick = 0; ch.envtick = 0;
ch.release = 0; ch.release = 0;
ch.env_vol = new EnvelopeFollower(inst.env_vol);
ch.env_pan = new EnvelopeFollower(inst.env_pan);
} }
} }
@ -186,6 +172,8 @@ function next_row() {
ch.release = 0; ch.release = 0;
ch.envtick = 0; ch.envtick = 0;
ch.vibratopos = 0; ch.vibratopos = 0;
ch.env_vol = new EnvelopeFollower(inst.env_vol);
ch.env_pan = new EnvelopeFollower(inst.env_pan);
UpdateChannelNote(ch, note); UpdateChannelNote(ch, note);
} }
} }
@ -200,6 +188,59 @@ function next_row() {
pat.innerHTML = patdisplay.join("\n"); pat.innerHTML = patdisplay.join("\n");
} }
function Envelope(points, type, sustain, loopstart, loopend) {
this.points = points;
this.type = type;
this.sustain = sustain;
this.loopstart = loopstart;
this.loopend = loopend;
}
Envelope.prototype.Get = function(ticks) {
// TODO: optimize follower with ptr
// or even do binary search here
var y0;
var env = this.points;
for (var i = 0; i < env.length; i += 2) {
y0 = env[i+1];
if (ticks < env[i]) {
var x0 = env[i-2];
var y0 = env[i-1];
var dx = env[i] - x0;
var dy = env[i+1] - y0;
return y0 + (ticks - x0) * dy / dx;
}
}
return y0;
}
function EnvelopeFollower(env) {
this.env = env;
this.tick = 0;
}
EnvelopeFollower.prototype.Tick = function(release) {
if (this.env === undefined) {
return 64;
}
var value = this.env.Get(this.tick);
if (this.env.type & 1) { // sustain?
// if we're sustaining a note, stop advancing the tick counter
if (!release &&
this.tick >= this.env.points[this.env.sustain*2]) {
return this.env.points[this.env.sustain*2 + 1];
}
}
this.tick++;
if (this.env.type & 2) { // envelope loop?
if (!release &&
this.tick > this.env.loopend) {
this.tick -= this.env.loopend - this.env.loopstart;
}
}
return value;
}
function next_tick() { function next_tick() {
cur_tick++; cur_tick++;
if (cur_tick >= tempo) { if (cur_tick >= tempo) {
@ -213,20 +254,8 @@ function next_tick() {
ch.effectfn(ch); ch.effectfn(ch);
} }
if (inst === undefined) continue; if (inst === undefined) continue;
if (inst.env_vol !== undefined) { ch.volE = ch.env_vol.Tick(ch.release);
ch.env_vol = GetEnvelope(inst.env_vol, ch.envtick); ch.panE = ch.env_pan.Tick(ch.release);
if (inst.env_vol_type & 2) { // sustain loop?
// if we're sustaining a note, leave env_vol alone
if (ch.release == 0) {
if (ch.envtick >= inst.env_vol[inst.env_vol_sustain*2]) {
continue;
}
}
}
ch.envtick++;
} else {
ch.env_vol = 64;
}
} }
} }
@ -263,10 +292,11 @@ function audio_cb(e) {
sample_end = looplen + inst.loop; sample_end = looplen + inst.loop;
} }
var samplen = inst.len; var samplen = inst.len;
var env_vol = ch.env_vol / 64.0; var volE = ch.volE / 64.0;
var p = ch.pan - 128; var panE = (ch.panE - 32);
var volL = env_vol * (128 - p) * ch.vol / 8192.0; var p = panE + ch.pan - 128;
var volR = env_vol * (128 + p) * ch.vol / 8192.0; var volL = volE * (128 - p) * ch.vol / 8192.0;
var volR = volE * (128 + p) * ch.vol / 8192.0;
if (volL < 0) volL = 0; if (volL < 0) volL = 0;
if (volR < 0) volR = 0; if (volR < 0) volR = 0;
if (volR == 0 && volL == 0) if (volR == 0 && volL == 0)
@ -277,8 +307,17 @@ function audio_cb(e) {
for (var i = offset; i < offset+tickduration; i++) { for (var i = offset; i < offset+tickduration; i++) {
if (ch.mute) break; if (ch.mute) break;
var s = samp[k|0]; var s = samp[k|0];
var si = ch.filter[0] * (s + ch.filterstate[0]) + ch.filter[1]*ch.filterstate[1] + ch.filter[2]*ch.filterstate[2]; // we low-pass filter here since we are resampling some arbitrary
ch.filterstate[2] = ch.filterstate[1]; ch.filterstate[1] = si; ch.filterstate[0] = s; // frequency to f_smp; this is an anti-aliasing filter and is
// implemented as an IIR butterworth filter (usually we'd use an FIR
// brick wall filter, but this is much simpler computationally and
// sounds fine)
var si = ch.filter[0] * (s + ch.filterstate[0]) +
ch.filter[1]*ch.filterstate[1] + ch.filter[2]*ch.filterstate[2];
ch.filterstate[2] = ch.filterstate[1];
ch.filterstate[1] = si; ch.filterstate[0] = s;
// we also low-pass filter volume changes with a simple one-zero,
// one-pole filter to avoid pops and clicks when volume changes.
ch.vL = popfilter_alpha * ch.vL + (1 - popfilter_alpha) * (volL + ch.vLprev) * 0.5; ch.vL = popfilter_alpha * ch.vL + (1 - popfilter_alpha) * (volL + ch.vLprev) * 0.5;
ch.vR = popfilter_alpha * ch.vR + (1 - popfilter_alpha) * (volR + ch.vRprev) * 0.5; ch.vR = popfilter_alpha * ch.vR + (1 - popfilter_alpha) * (volR + ch.vRprev) * 0.5;
ch.vLprev = volL; ch.vLprev = volL;
@ -292,12 +331,19 @@ function audio_cb(e) {
} else { } else {
// kill sample // kill sample
ch.inst = undefined; ch.inst = undefined;
// ramp down with the pop filter // ramp down to zero with the pop filter
// if the sample ends right before the end of the tick (or the end
// of the buffer), we could still get a pop but *usually* it's
// hidden behind other changes in the tick... there's only so much
// we can do here, anyway. i guess we could hold the dc offset...
var rampend = Math.min(offset+tickduration, i+200); var rampend = Math.min(offset+tickduration, i+200);
for (i++; i < rampend; i++) { for (i++; i < rampend; i++) {
// fill rest of buffer with filtered silence to avoid a pop // fill rest of buffer with filtered silence to avoid a pop
var si = popfilter[0] * (ch.filterstate[0]) + popfilter[1]*ch.filterstate[1] + popfilter[2]*ch.filterstate[2]; var si = popfilter[0] * (ch.filterstate[0]) +
ch.filterstate[2] = ch.filterstate[1]; ch.filterstate[1] = si; ch.filterstate[0] = 0; popfilter[1]*ch.filterstate[1] +
popfilter[2]*ch.filterstate[2];
ch.filterstate[2] = ch.filterstate[1];
ch.filterstate[1] = si; ch.filterstate[0] = 0;
dataL[i] += ch.vL * si; dataL[i] += ch.vL * si;
dataR[i] += ch.vR * si; dataR[i] += ch.vR * si;
} }
@ -568,10 +614,19 @@ function playXM(arrayBuf) {
var env_vol_sustain = dv.getUint8(idx+227); var env_vol_sustain = dv.getUint8(idx+227);
var env_vol_loop_start = dv.getUint8(idx+228); var env_vol_loop_start = dv.getUint8(idx+228);
var env_vol_loop_end = dv.getUint8(idx+229); var env_vol_loop_end = dv.getUint8(idx+229);
var env_npan = dv.getUint8(idx+226);
var env_pan_type = dv.getUint8(idx+234);
var env_pan_sustain = dv.getUint8(idx+230);
var env_pan_loop_start = dv.getUint8(idx+231);
var env_pan_loop_end = dv.getUint8(idx+232);
env_vol = []; env_vol = [];
for (var j = 0; j < env_nvol*2; j++) { for (var j = 0; j < env_nvol*2; j++) {
env_vol.push(dv.getUint16(idx+129+j*2, true)); env_vol.push(dv.getUint16(idx+129+j*2, true));
} }
env_pan = [];
for (var j = 0; j < env_npan*2; j++) {
env_pan.push(dv.getUint16(idx+177+j*2, true));
}
if (nsamp > 0) { if (nsamp > 0) {
// FIXME: ignoring keymaps for now and assuming 1 sample / instrument // FIXME: ignoring keymaps for now and assuming 1 sample / instrument
// var keymap = getarray(dv, idx+0x21); // var keymap = getarray(dv, idx+0x21);
@ -607,11 +662,20 @@ function playXM(arrayBuf) {
'sampledata': ConvertSample(new Uint8Array(arrayBuf, sampleoffset, samplen), samptype & 4), 'sampledata': ConvertSample(new Uint8Array(arrayBuf, sampleoffset, samplen), samptype & 4),
}; };
if (env_vol_type) { if (env_vol_type) {
inst.env_vol = env_vol; inst.env_vol = new Envelope(
inst.env_vol_type = env_vol_type; env_vol,
inst.env_vol_sustain = env_vol_sustain; env_vol_type,
inst.env_vol_loop_start = env_vol_loop_start; env_vol_sustain,
inst.env_vol_loop_end = env_vol_loop_end; env_vol_loop_start,
env_vol_loop_end);
}
if (env_pan_type) {
inst.env_pan = new Envelope(
env_pan,
env_pan_type,
env_pan_sustain,
env_pan_loop_start,
env_pan_loop_end);
} }
instruments.push(inst); instruments.push(inst);
} else { } else {