Help with keeping oscilloscope real time

[Craz1000]

I seem to ask for help a lot it seems lol.

So after completing my Zelda game and posting it here, it has left me with some free time. Enough time to catch up with things I have been putting off around the house. Lately I have been playing with some ideas and concepts, One of which requires an oscilloscope of audio in real time. I have been playing with the _memsound example and another example I have found on here. However I cant seem to get it quite right. What I see graphically is either behind (i=i+2) or ahead (i=i+3) of the audio. I have tried doing a bytes per second on the fly adjustment, a frames per second adjustment, and a "how much time has advanced on the audio since the last display refresh adjustment." Nothing seems to work quite right.

Code: QB64: [Select]

1. Dim i As _Offset
2. Dim leftchannel As _MEM
3.  
4. Display& = _NewImage(600, 200, 32)
5. Buffer& = _NewImage(600, 200, 32)
6.  
7. Screen Display&
8. _Dest Buffer&
9.  
10.  
11. song& = _SndOpen("Sounds\singing stars.mp3") 'replace drums.ogg with a sound file you have
12.  
13.  
14. leftchannel = _MemSound(song&, 1)
15.  
16.  
17. i = 0
18. PositionDifference = 2
19. _SndPlay song&
20.  
21.  
22. Do
23.     _MemGet leftchannel, leftchannel.OFFSET + i, l% 'get sound data
24.  
25.     Locate 1, 1: Print leftchannel.OFFSET; "/"; leftchannel.SIZE, dframes, leftchannel.ELEMENTSIZE
26.     nextposl = map(l%, -32768, 32767, -_Height / 2, _Height / 2) + (_Height / 2)
27.     Line (x, prevposl)-(x + 1, nextposl + 2), _RGB32(254, 0, 0), BF
28.     prevposl = nextposl
29.  
30.  
31.  
32.  
33.     x = x + 1
34.     If x > _Width Then
35.         x = 0
36.         dframes = frames
37.         frames = 0
38.         _PutImage , Buffer&, Display&
39.  
40.         Cls
41.     End If
42.     i = i + 2
43.  
44.     If i + 2 > leftchannel.SIZE Then Exit Do
45.     frames = frames + 1
46.  
47.  
48.  
49.  
50. Loop
51.  
52. _SndClose song& 'closing the sound releases the mem blocks
53.  
54.  
55. Function map! (value!, minRange!, maxRange!, newMinRange!, newMaxRange!)
56.     map! = ((value! - minRange!) / (maxRange! - minRange!)) * (newMaxRange! - newMinRange!) + newMinRange!
57. End Function
58.