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Hi brett,

I have been playing with the DSP unit on our mp3 player prototype for some time now, and have been trying to get rid of some ‘crackles’ in the audio that i assumed were my algorithm. However we have used the DSP reverb sample with a plain old sin wave with a silence at the end and the crackle is still there!. We have tried to debug the algorithm but could find nothing wrong with it. So we started to experiment and found the only way we could change the nature of the crackles was to change the output rate (i.e. 11000 is worse that 16000). So we think we may have bug, maybe in mixbuffer routine. The sample program with one tap compiled uses about 1% cpu time , so i dont think its a buffer underrun or somesuch (also if you mix ‘nothing’ the crackles disappear). this problem exists on WINCE 3.0 pocketpc 2002 , pocketpc 2003 (XDA, XDA2,IPAQ), ive also used the fmod3.71 and the pre-release 3.72 -both the same.
Any ideas what we maybe doing wrong?
Greg.

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its your sample code, and assuming the malloc says bufferlen * 4 im assuming 16bit stereo, and if it was wrong it wouldnt be a few crackles at the end of each echo it would be complete sounding madness.
G.

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ill email the entire directory source code (99% your dsp sample) and the fmod.dll and fmod.lib that im using… that cause crackles.
G

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Yup , thanks brett, nice and speedy fix as usual.
G.

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