Mix like on a turntable

[Petr]

Imagine that your computer is a DJ on a turntable and randomly changes direction and speed during playback. This is the first (but not the last) version of this effect.

Code: QB64: [Select]

1. misto = 44100 * 5 '5 seconds after music start playing start effect
2. mistoE = misto + 88200 'effect ends 2 seconds after effect start
3. rychlost = 88200
4.  
5. Dim As _MEM L, R, L2, R2
6. Dim As Integer LS, RS
7.  
8. file$ = "a.mp3"
9. Print "Opening sound file "; file$
10. f = _SndOpen(file$)
11. L = _MemSound(f, 1)
12. R = _MemSound(f, 2)
13.  
14. Type SND
15.     L As Integer
16.     R As Integer
17. End Type
18. Dim snd(_SndRate * _SndLen(f)) As SND
19.  
20. Print "Creating standard array"
21. Do Until Done& = L.SIZE
22.     snd(i).L = _MemGet(L, L.OFFSET + Done&, Integer)
23.     snd(i).R = _MemGet(R, R.OFFSET + Done&, Integer)
24.     i = i + 1
25.     Done& = Done& + 2
26. Loop
27.  
28. i = i - 2
29.  
30. Dim snd2(3 * UBound(snd)) As SND 'this time i do not calculate array size - because this demo use random output lenght
31. zacatek = misto
32. konec = mistoE
33. psi2 = _Pi(1) / (zacatek - konec)
34. Dim As Long misto, mistoE
35.  
36. copy = 0
37. Print "Creating pseudo mix"
38. Randomize Timer
39. Do Until copy >= UBound(snd) - 1
40.     If original > misto And original < mistoE Then
41.         k2 = k2 + psi2
42.         newi = Sin(k2) * 44100
43.         copy = ocopy + newi
44.         original = original + Abs(Sin(k2))
45.     Else
46.         ocopy = copy
47.         copy = copy + 1
48.         original = Int(original + 1)
49.     End If
50.  
51.     If original > mistoE + 44100 Then 'pause between two mix hits (44100 = 1 sec)
52.         misto = original + 44100 * Rnd 'effect start in samples (44100 x time)
53.         mistoE = misto + 44100 * Rnd + 500 'effect end in samples
54.         zacatek = misto
55.         konec = mistoE
56.         psi2 = _Pi(1) / (zacatek - konec)
57.  
58.         If misto > UBound(snd2) Or misto2 > UBound(snd2) Then misto = 0: mistoE = 0
59.     End If
60.  
61.  
62.  
63.     If original > UBound(snd2) Then Print "Snd2 overlow"
64.     If copy > UBound(snd) Then Print "Snd overlow"; copy; krok
65.  
66.     snd2(original).L = snd(copy).L
67.     snd2(original).R = snd(copy).R
68. Loop
69.  
70. Print "Playing"
71. For test = 0 To original
72.     _SndRaw snd2(test).L / 32768, snd2(test).R / 32768
73. Next
74.  
75.