
                             DSP SOUND PROCESSING
                                       
   Once you know how the sound system works, it is not very difficult to
   make a simple sound processing routine. All you do is use the
   Devconnect XBIOS call to connect the DSP between your source and
   destination devices. So for example, say you wanted to do some
   real-time processing, you connect the ADC to the DSP IN, and the DSP
   OUT to the DAC.
   
   Do this with the lines:
   

Devconnect(3,2,srcclk,prescale,1);
Devconnect(1,8,srcclk,prescale,1);

   Or if your an assembler freak:
   

        move.w  #1,-(sp)
        move.w  prescale,-(sp)
        move.w  srcclk,-(sp)
        move.w  #2,-(sp)
        move.w  #3,-(sp)
        move.w  #139,-(sp)
        trap    #14
        lea     12(sp),sp

        move.w  #1,-(sp)
        move.w  prescale,-(sp)
        move.w  srcclk,-(sp)
        move.w  #8,-(sp)
        move.w  #1,-(sp)
        move.w  #139,-(sp)
        trap    #14
        lea     12(sp),sp

   However, if all you do is this, then you will get nothing (unless
   something has allready used the DSP, in which case it will be
   unpredictable). Before you actually connect the DSP up, you should
   have the DSP program which actually does the processing loaded. Use
   DSP_reserve to reserve some space, and then DSP_LoadProg to
   load/execute your .LOD file.
   
   The .LOD file will have been written in DSP assembler, with some code
   to recieve the data, and to transmit the data. I have code for this,
   and will make it available in the near future.
   
   As I know nothing about actual processing of audio data (to do
   interesting things like flange, reverb etc.) I will not be covering
   this side of it. If YOU know something about that, then maybe you
   could send me some details to me, and I'll include them here...
   
   
     _________________________________________________________________
   
   Back to Falcon page.
   Back to Atari Pages.
    Anthony Jacques : jacquesa@cs.man.ac.uk
