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Active Forums => Programs => Topic started by: Craz1000 on July 18, 2021, 11:10:06 pm

Title: Help with keeping oscilloscope real time
Post by: Craz1000 on July 18, 2021, 11:10:06 pm
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]
  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.  
  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.  
  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!
  58.  

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