import math, wave, struct
SR=48000
HARM=(1.00, 0.85, 0.10, 0.02)   # mesmo timbre medido nas referencias
ATTACK=0.004

def note(f, dur, tau):
    n=int(SR*dur); o=[]
    for i in range(n):
        t=i/SR
        s=sum(a*math.sin(2*math.pi*f*(k+1)*t) for k,a in enumerate(HARM))
        o.append(s*min(1.0,t/ATTACK)*math.exp(-t/tau))
    return o

def peak_rms(x, win=int(SR*0.01)):
    return max(math.sqrt(sum(v*v for v in x[i:i+win])/win)
               for i in range(0,len(x)-win,win))

def write(name, buf, target):
    g=target/max(1e-9,peak_rms(buf))
    pk=max(abs(s*g) for s in buf)
    if pk>0.97: g*=0.97/pk
    with wave.open(name,'w') as w:
        w.setnchannels(1); w.setsampwidth(2); w.setframerate(SR)
        w.writeframes(b''.join(struct.pack('<h',int(max(-1,min(1,s*g))*32767)) for s in buf))
    print(f"{name}: pico RMS {peak_rms([s*g for s in buf]):.3f}, {len(buf)/SR:.2f}s")

G3, G4 = 196.00, 392.00
# Decaimento mais curto (0.13 vs 0.19) e volume ~55% do som de call:
# entrar/sair da tela dispara muitas vezes durante uma transmissao.
write('stream_user_joined.wav', note(G4, 0.42, 0.13), 0.20)
write('stream_user_left.wav',   note(G3, 0.42, 0.13), 0.20)