Audio stuttering/jittering/distortion/crackling

neoman · 30 May 2016, 11:35

(Just tested this in WinUAE yet)

Built some demo code here which fires up Kalms ADPCM and then goes into endless loop. Before that loop I register a VB-Handler which decodes and feeds the audio samples (using Kalms library)

When I, in my endless loop, put a Wait for VBL or even Wait(0) or Delay(1), the audio is sounding OK. If I don't do that the audio starts to stutter and plays very slowly.

I disabled all interrupts except VB, disabled all DMAs except Master/Audio, and disabled task switching.

Why is that? What is happening here? Is Audio DMA "slowed" down while CPU is running my endless loop?

I'm coding some demo at the moment and got some effects which take longer than a frame but I still need to feed audio data every frame (that's why I use the VBI).

Any idea how to proceed? Using Audio Interrupts?

neoman · 30 May 2016, 14:40

I tested it on H/W now and it works.
So it seems to be some issue with WinUAE. I'm using the latest version.

30 May 2016, 11:35	#1
neoman titan sucks! Join Date: Dec 2012 Location: munich/germany Posts: 54	Audio stuttering/jittering/distortion/crackling (Just tested this in WinUAE yet) Built some demo code here which fires up Kalms ADPCM and then goes into endless loop. Before that loop I register a VB-Handler which decodes and feeds the audio samples (using Kalms library) When I, in my endless loop, put a Wait for VBL or even Wait(0) or Delay(1), the audio is sounding OK. If I don't do that the audio starts to stutter and plays very slowly. I disabled all interrupts except VB, disabled all DMAs except Master/Audio, and disabled task switching. Why is that? What is happening here? Is Audio DMA "slowed" down while CPU is running my endless loop? I'm coding some demo at the moment and got some effects which take longer than a frame but I still need to feed audio data every frame (that's why I use the VBI). Any idea how to proceed? Using Audio Interrupts?

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30 May 2016, 14:40	#2
neoman titan sucks! Join Date: Dec 2012 Location: munich/germany Posts: 54	I tested it on H/W now and it works. So it seems to be some issue with WinUAE. I'm using the latest version.

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