desc:GFX Model 15
//tags: channel strip preamp tape saturation lo-fi hiss portable cassette
//author: JGWizrad / Garden FX (GFX)
//
// Requires gfx-output, gfx-input, gfx-ui, gfx-panel and gfx-dyn (.jsfx-inc) in the same folder.
//
// A single-channel strip in the spirit of the early-80s ultra-portable cassette multitracker ecosystem:
// a low-voltage, battery-driven preamp, a fixed broad-stroke tone stage, a sluggish tape-head saturation
// with a level-dependent top-end roll-off, and an open, breathing hiss floor (no sophisticated noise
// reduction - just a simple single-band lift/unlift). Use it to push stems toward a compressed, boxy,
// warm little-recorder character (personal use; the sound is designed from scratch).
//
// GAIN    - the low-voltage op-amp preamp: pushed past noon it clips early and asymmetrically, smearing
//           transients and thickening the low-mids.
// TREBLE / BASS - fixed broad shelves (10 kHz / 100 Hz). Push them hard and the shelf itself turns a
//           little gritty and grainy rather than staying clean.
// TAPE    DRIVE - the tape saturation / hysteresis amount: a sluggish magnetic memory plus a dynamic
//                 top-end roll-off that closes down as level rises, gluing transients together.
//         WOW   - wow and flutter in the transport.
//         HISS  - the tape's own noise floor: it ducks a little under signal and swells back in the gaps.
//         AGE   - an older, worn tape: the top end goes further and dropouts creep in.
//         NR    - the simple B-type-style noise reduction, in / out.
// MIX     - blend of the coloured signal against the dry input.
// IN/OUT  - input TRIM and GUARD (gentle auto-leveller), OUTPUT level, and the output band-saturation /
//           clipper / limiter stage.
// PRESETS.

import gfx-output.jsfx-inc
import gfx-input.jsfx-inc
import gfx-ui.jsfx-inc
import gfx-panel.jsfx-inc
import gfx-dyn.jsfx-inc

slider1:6<-6,24,0.1>-Gain (dB)
slider2:0<-10,10,0.1>-Treble (10 kHz) (dB)
slider3:0<-10,10,0.1>-Bass (100 Hz) (dB)
slider4:35<0,100,1>-Tape drive (%)
slider5:25<0,100,1>-Wow / flutter (%)
slider6:50<0,100,1>-Hiss (%)
slider7:15<0,100,1>-Age (%)
slider8:1<0,1,1{Off,On}>-Noise reduction
slider9:100<0,100,1>-Mix (%)
slider10:0<-24,12,0.1>-Output (dB)
slider11:0<0,100,1>-Band sat (%)
slider12:30<0,100,1>-Bias (%)
slider13:120<40,400,1>-Sat low band (Hz)
slider14:6000<2000,16000,10>-Sat high band (Hz)
slider15:-0.3<-24,0,0.1>-Ceiling / limit threshold (dB)
slider16:1<0,2,1{Off,Clip,Limit}>-Output stage
slider17:0<-24,12,0.1>-Input trim (dB)
slider18:1<0,1,1{Off,On}>-Input guard

in_pin:left input
in_pin:right input
out_pin:left output
out_pin:right output

@init
#ui_man = "gfx-model-15";

WBSZ = 8192; WBMSK = WBSZ - 1;                     // wow delay lines: 2 x 8192 from 10000
memset(10000, 0, WBSZ * 2);

// ---------- the low-voltage preamp: asymmetric soft clip, unity small-signal gain ----------
function f15_pre(x) ( ost_curve(x * g_lin, pre_drv, pre_bias) );

// ---------- fixed shelving EQ: the added band itself saturates a little ----------
function f15_eq_set() instance(ts, bsf) ( ts.bq_set(3, 10000, 0.6, tr_db); bsf.bq_set(4, 100, 0.6, bs_db); );
function f15_eq(x) instance(ts, bsf) local(y, addhi, bsy, addlo) (
  y = ts.bq_run(x);
  addhi = y - x; addhi = ost_tanh(addhi * shelf_drv) / max(shelf_drv, 0.0001);
  y = x + addhi;
  bsy = bsf.bq_run(y);
  addlo = bsy - y; addlo = ost_tanh(addlo * shelf_drv * 0.6) / max(shelf_drv * 0.6, 0.0001);
  y + addlo;
);

// ---------- the tape: hysteresis lag + saturation, dynamic top-end roll-off, hiss, simple NR ----------
function f15_tape_set() instance(hb) ( hb.bq_set(2, 80, 1.1, 2.0); );   // fixed little head bump
function f15_tape(x, buf, nz, nron) instance(hy, env, lp, bhr, ber, bhp, bep, hsv, hb)
  local(y, h, k, cutoff, lpc, rp, i, fr, duck) (
  // record-side NR encode: lift the quiet highs before the "tape"
  nron ? (
    bhr += (x - bhr) * b_c; h = x - bhr;
    ber += (abs(h) - ber) * nr_c; k = 2.0 * (1 - min(ber / 0.06, 1));
    y = x + k * h;
  ) : y = x;
  // hysteresis: a sluggish magnetic memory blended in ahead of the saturation curve
  hy += (y - hy) * hy_c;
  y = 0.6 * y + 0.4 * hy;
  y = y + tape_wet * (ost_curve(y, drv_k, bias_tape) - y);
  // fixed head bump
  y = hb.bq_run(y);
  // transport: wow / flutter (shared wdel, each side its own delay line)
  buf[wpos] = y;
  rp = wpos - wdel; rp < 0 ? rp += WBSZ;
  i = floor(rp); fr = rp - i;
  y = buf[i & WBMSK] * (1 - fr) + buf[(i + 1) & WBMSK] * fr;
  // dynamic top-end roll-off: closes down as level rises (the "gluing" playback head loss)
  env += (abs(y) - env) * env_c;
  cutoff = max(hf_min, hf_max - (hf_max - hf_min) * min(env * env_gain, 1));
  lpc = 1 - exp(-2 * $pi * min(cutoff, srate * 0.45) / srate);
  lp += (y - lp) * lpc;
  y = lp * drop_g;
  // the tape's own hiss: ducks under signal, swells back in the gaps
  hsv += (abs(x) - hsv) * (abs(x) > hsv ? hiss_fast : hiss_slow);
  duck = 1 / (1 + 4 * hsv);
  y += nz * hiss_g * duck;
  // playback-side NR decode: the inverse lift, taken back down
  nron ? (
    bhp += (y - bhp) * b_c; h = y - bhp;
    bep += (abs(h) - bep) * nr_c; k = 2.0 * (1 - min(bep / 0.06, 1));
    y -= k / (1 + k) * h;
  );
  y;
);

function update() (
  g_db = slider1; g_lin = 10 ^ (g_db / 20);
  pre_pos = max(g_db, 0) / 24;
  pre_drv = 1 + 2.2 * pre_pos;
  pre_bias = 0.05 + 0.11 * pre_pos;

  tr_db = slider2; bs_db = slider3;
  shelf_drv = 1 + (abs(tr_db) + abs(bs_db)) / 10 * 1.1;

  tape_amt = slider4 / 100;
  hy_c = 1 - exp(-1 / (0.008 * srate));
  drv_k = 1 + 2 * tape_amt;
  bias_tape = 0.03 + 0.05 * tape_amt;
  tape_wet = min(tape_amt * 1.4, 1);

  age = slider7 / 100;
  hf_max = 9500;
  hf_min = max(2800, hf_max - 6000 * tape_amt - 2000 * age);
  env_c = 1 - exp(-1 / (0.015 * srate));
  env_gain = 2 + 3 * tape_amt;

  b_c = 1 - exp(-2 * $pi * 3000 / srate);
  nr_c = 1 - exp(-1 / (0.008 * srate));

  wow_a = slider5 / 100;
  hiss_g = (slider6 / 50) * 10 ^ (-50 / 20);
  hiss_fast = 1 - exp(-1 / (0.01 * srate));
  hiss_slow = 1 - exp(-1 / (0.4 * srate));
  nr_on = slider8;
  mix_t = slider9 / 100;
  out_t = 10 ^ (slider10 / 20);

  eqL.f15_eq_set(); eqR.f15_eq_set();
  tpL.f15_tape_set(); tpR.f15_tape_set();
  in_setup(slider17, slider18);
  ost_setup(slider11 / 100, slider12 / 100, slider13, slider14, slider15, slider16);
);

// ---------- presets (gain, treble, bass, tape, wow, hiss, age, nr, mix, output) ----------
function setp(g, tr, bs, dr, w, h, a, n, mx) (
  slider1 = g; slider2 = tr; slider3 = bs; slider4 = dr; slider5 = w; slider6 = h; slider7 = a; slider8 = n; slider9 = mx;
);
function pname(p) (
  p == 1 ? "Bedroom Demo" :
  p == 2 ? "Hot and Boxy" :
  p == 3 ? "No NR, Open Tape" :
  p == 4 ? "Worn-out Portable" :
  p == 5 ? "Clean-ish Portable" :
  "Reset all to defaults";
);
function load_preset(p) (
  p == 1 ? setp(6, 1, 1, 45, 25, 50, 15, 1, 100) :        // Bedroom Demo
  p == 2 ? setp(15, 2, 2, 70, 35, 60, 25, 1, 100) :       // Hot and Boxy
  p == 3 ? setp(9, 0, 0, 55, 30, 90, 20, 0, 100) :        // No NR, Open Tape
  p == 4 ? setp(12, -1, 3, 60, 70, 75, 65, 1, 100) :      // Worn-out Portable
  p == 5 ? setp(0, 0, 0, 15, 15, 40, 5, 1, 100);          // Clean-ish Portable
  p >= 1 && p <= 5 ? slider_automate(1023);
  p == 6 ? (                                                // Reset all to defaults
    setp(6, 0, 0, 35, 25, 50, 15, 1, 100); slider10 = 0;
    slider11 = 0; slider12 = 30; slider13 = 120; slider14 = 6000; slider15 = -0.3; slider16 = 1;
    slider17 = 0; slider18 = 1;
    slider_automate(262143);
  );
);

ost_init(40000); ostL.ost_ch_init(); ostR.ost_ch_init();
in_init();
sm = 1 - exp(-1 / (0.02 * srate));
vuc = 1 - exp(-1 / (0.3 * srate));
dr_r = 1 - exp(-1 / (0.03 * srate));
wpos = 0; drop_g = 1; drop_t = 1;
cur_preset = 1;
!ui_dflt ? ui_thm = 5; !ui_dflt ? ui_hw = 1;
update();
mix_s = mix_t; out_s = out_t;
ui_dflt = 1;

@slider
update();

@block
update();

@serialize
file_var(0, ui_sz);

@sample
in_process(spl0, spl1);
inL = in_l; inR = in_r;

// ---------- transport: wow (0.6 Hz + a slow wander) and flutter (6 Hz) ----------
wph += 0.6 / srate; wph -= floor(wph);
fph += 6.2 / srate; fph -= floor(fph);
wnd += ((rand(2) - 1) - wnd) * 0.00002;
wdel = (2 + wow_a * (0.45 * sin(2 * $pi * wph) + 1.5 * wnd + 0.06 * sin(2 * $pi * fph))) * 0.001 * srate + 2;
// dropouts (AGE)
age > 0 && rand(1) < age * age * 1.2 / srate ? ( drop_t = 10 ^ (-(2 + rand(6)) / 20); drop_n = (0.01 + rand(0.04)) * srate; );
drop_n > 0 ? drop_n -= 1 : drop_t = 1;
drop_g += (drop_t - drop_g) * dr_r;
// hiss: an independent noise per side, gently pink
NZ0 += ((rand(2) - 1) - NZ0) * 0.5;
NZ1 += ((rand(2) - 1) - NZ1) * 0.5;

pL = f15_pre(inL); pR = f15_pre(inR);
eL = eqL.f15_eq(pL); eR = eqR.f15_eq(pR);
tL = tpL.f15_tape(eL, 10000, NZ0, nr_on); tR = tpR.f15_tape(eR, 10000 + WBSZ, NZ1, nr_on);
wpos = (wpos + 1) & WBMSK;

mix_s += (mix_t - mix_s) * sm;
out_s += (out_t - out_s) * sm;

oL = inL * (1 - mix_s) + tL * mix_s;
oR = inR * (1 - mix_s) + tR * mix_s;

oL = ostL.ost_band(oL) * out_s;
oR = ostR.ost_band(oR) * out_s;
ost_out(oL, oR);
spl0 = ost_l; spl1 = ost_r;
vmL += (spl0 * spl0 - vmL) * vuc; vmR += (spl1 * spl1 - vmR) * vuc;
pkL = max(pkL, abs(spl0)); pkR = max(pkR, abs(spl1));

@gfx 760 404
ui_begin(760, 404);
PNL = 0x1B1B1D; INK = 0xEDEAE2; ACC = 0xE8502A; WIN = 0x0E0E10;
dy_ink = INK; dy_bg = PNL; dy_kst = 20; dy_nov = 1;

ui_col(0x0A0A0B); gfx_rect(0, 0, gfx_w, gfx_h);
pk_chassis(8 * sc, 4 * sc, 744 * sc, 396 * sc, PNL);
ui_col(INK); gfx_circle(40 * sc, 34 * sc, 14 * sc, 1, 1);
gfx_setfont(4); ui_col(PNL); ui_text(40 * sc, 29 * sc, "GFX");
gfx_setfont(6, "Trebuchet MS", 24 * sc, 'b'); ui_col(INK); gfx_x = 62 * sc; gfx_y = 20 * sc; gfx_drawstr("MODEL 15");
gfx_setfont(4); ui_col(ACC); gfx_x = 212 * sc; gfx_y = 30 * sc; gfx_drawstr("LO-FI CHANNEL");
ui_button(388 * sc, 20 * sc, 26 * sc, 28 * sc, "<", 0, 1) ? (
  cur_preset = cur_preset <= 1 ? 6 : cur_preset - 1;
  load_preset(cur_preset);
);
ui_button(416 * sc, 20 * sc, 26 * sc, 28 * sc, ">", 0, 1) ? (
  cur_preset = cur_preset >= 6 ? 1 : cur_preset + 1;
  load_preset(cur_preset);
);
ui_button(450 * sc, 20 * sc, 90 * sc, 28 * sc, "PRESETS", 0, 1) ? (
  gfx_x = 450 * sc; gfx_y = 48 * sc;
  cur_preset = gfx_showmenu("Bedroom Demo|Hot and Boxy|No NR, Open Tape|Worn-out Portable|Clean-ish Portable|Reset all to defaults");
  cur_preset > 0 ? load_preset(cur_preset);
);
ui_size_picker(560 * sc, 22 * sc);
pk_lcd(624 * sc, 16 * sc, 120 * sc, 32 * sc, 0);
pk_lcdfont(9, 9 * sc); ui_col(pk_lcdc);
gfx_x = 630 * sc; gfx_y = 22 * sc; gfx_drawstr("PATCH");
pk_lcdfont(9, 11 * sc); ui_col(pk_lcdc);
gfx_x = 630 * sc; gfx_y = 33 * sc; gfx_drawstr(pname(cur_preset));
ui_col(ACC); gfx_rect(14 * sc, 60 * sc, 732 * sc, 3 * sc);

// ---------- CHANNEL: gain, EQ, trim / guard, mix ----------
ui_cola(INK, 0.06); gfx_rect(22 * sc, 72 * sc, 368 * sc, 316 * sc);
gfx_setfont(6, "Trebuchet MS", 13 * sc, 'b'); ui_col(ACC); gfx_x = 34 * sc; gfx_y = 82 * sc; gfx_drawstr("CHANNEL");
ui_col(ACC); gfx_rect(34 * sc, 98 * sc, 344 * sc, 1 * sc);
LPK = max(max(pkL, pkR), LPK * 0.9); pkL = 0; pkR = 0;
pk_led(206 * sc, 112 * sc, 3.5 * sc, LPK > 0.001, dy_grn);
sprintf(#v, "%+.1f dB", slider1); dy_knob(100, 170, 24, 1, -6, 24, 6, 0, ACC, "GAIN", #v);
sprintf(#v, "%+.1f dB", slider2); dy_knob(206, 170, 16, 2, -10, 10, 0, 0, 0xB8BCC2, "TREBLE", #v);
sprintf(#v, "%+.1f dB", slider3); dy_knob(312, 170, 16, 3, -10, 10, 0, 0, 0xB8BCC2, "BASS", #v);
sprintf(#v, "%+.1f dB", slider17); dy_knob(100, 270, 16, 17, -24, 12, 0, 0, 0xB8BCC2, "TRIM", #v);
dy_btn(188, 254, slider18, dy_grn, "GUARD") ? ( slider18 = 1 - slider18; ui_auto(18); );
sprintf(#v, "%.0f%%", slider9); dy_knob(312, 270, 16, 9, 0, 100, 100, 0, 0xF2F2EE, "MIX", #v);

// ---------- meters ----------
vuL.ui_vu(400 * sc, 72 * sc, 170 * sc, 104 * sc, 10 * log10(vmL + 0.0000000001) + 18, "L");
vuR.ui_vu(576 * sc, 72 * sc, 170 * sc, 104 * sc, 10 * log10(vmR + 0.0000000001) + 18, "R");

// ---------- tape + output ----------
ui_cola(INK, 0.06); gfx_rect(400 * sc, 188 * sc, 346 * sc, 200 * sc);
gfx_setfont(6, "Trebuchet MS", 13 * sc, 'b'); ui_col(ACC); gfx_x = 410 * sc; gfx_y = 194 * sc; gfx_drawstr("TAPE");
ui_col(ACC); gfx_rect(410 * sc, 210 * sc, 326 * sc, 1 * sc);
dy_nov = 0;
sprintf(#v, "%.0f%%", slider4); dy_knob(436, 250, 17, 4, 0, 100, 35, 0, ACC, "DRIVE", #v);
sprintf(#v, "%.0f", slider5); dy_knob(504, 250, 17, 5, 0, 100, 25, 0, 0xB8BCC2, "WOW", #v);
sprintf(#v, "%.0f", slider6); dy_knob(572, 250, 17, 6, 0, 100, 50, 0, 0xB8BCC2, "HISS", #v);
sprintf(#v, "%.0f", slider7); dy_knob(640, 250, 17, 7, 0, 100, 15, 0, 0xB8BCC2, "AGE", #v);
sprintf(#v, "%+.1f dB", slider10); dy_knob(710, 250, 20, 10, -24, 12, 0, 0, 0xF2F2EE, "OUTPUT", #v);
dy_btn(650, 330, slider8, dy_grn, "NR") ? ( slider8 = 1 - slider8; ui_auto(8); );
dy_lbl(574, 338, "STANDARD SPEED", 0.7);
dy_lbl(574, 352, "B-TYPE NR", 0.7);

pk_end();
ui_end();