Steps on programing with ASIO?????????

[pakkko]

Hi every body, i´m a newbie in the computer music programming, but an experimented computer music software user. That fact encourage me too much because now i could program a sinewave generator using only the api´s. Now i´m about to program the same app with directsoud.

I need your help because i want to program the same stuff using the ASIO drivers. i have the ASIO SDK but i just dont get it.

Compiler: visual c++ , visual c++.net

[DevilishHabib]

Hi there,
Just use Portaudio library, it's very simple and can be used with WinMM, DX & ASIO interfaces. It is open source so you can see how ASIO stuff was coded.
I'm using it with ASIO in a simple vst host I wrote for testing my vst plugin and it works great

[stinos]

Hi
If you're interested I can post a C++ wrapper I once wrote for the ASIO sdk, it allows you to start/stop a card and read/write samples from it in a convenient way.
Portaudio is not too bad, but it sometimes drops the first buffers (not with Asio I think, but it does with mme)

[pakkko]

ok, that would be nice!!!

[caoxiang]

Hi
If you're interested I can post a C++ wrapper I once wrote for the ASIO sdk, it allows you to start/stop a card and read/write samples from it in a convenient way.
Portaudio is not too bad, but it sometimes drops the first buffers (not with Asio I think, but it does with mme)

that is also helpful for me...

[stinos]

here you go:

I wrote a little sample to show how to use it, it will multiply the input with 2 and write it to the output for approx. 5 seconds.
All processing happens in the callback; if you have a gui or another thread communicating with your processing (eg to set m_dGain or if using vst plugins) it's a good idea to use mutexes.

Code: Select all

  //object passed to callback
class CallbackData
{
public:
  CallbackData() :
    m_dGain( 1.0 ), 
    m_pWrapper( 0 ),
    m_pScratchBuf( 0 )
  {
  }
  ~CallbackData()
  {
    delete m_pScratchBuf;
  }

  void Init( iowrappers::AsioWrapper* const ac_pWrapper, const double ac_dGain )
  {
    m_dGain = ac_dGain;
    m_pWrapper = ac_pWrapper;
    m_pScratchBuf = new CChanBufShort( ac_pWrapper->mf_nGetIChan(), ac_pWrapper->mf_nGetBuffSize(), true );
  }

  double          m_dGain;
  AsioWrapper*    m_pWrapper;
  CChanBufShort*  m_pScratchBuf;
};

  //callback
void pCallback( void* pData )
{
  CallbackData* p = (CallbackData*)pData;
  
  const double          c_dGain   = p->m_dGain;
  const unsigned        c_nChan   = p->m_pWrapper->mf_nGetIChan();
  const unsigned        c_nSize   = p->m_pWrapper->mf_nGetBuffSize();
  const CChanStrShort&  c_Input   = p->m_pWrapper->mf_nReadSamples(); 
  CChanBufShort*        Scratch   = p->m_pScratchBuf;

  for( unsigned i = 0 ; i < c_nChan ; ++i )
  {
    for( unsigned j = 0 ; j < c_nSize ; ++j )
    {
      Scratch->mp_SetSample( i, j, c_Input( i, j ) ); 
    }
  }  
  p->m_pWrapper->mf_nWriteSamples( *Scratch );
}

  /**
    * ACTUAL CODE STARTS HERE
    *************************/
const unsigned      c_nChannels   = 2; 
const unsigned      c_nBufferSize = 512;  
const unsigned long c_lSampleRate = 48000;

AsioWrapper p;
CallbackData myData;
t_DriverNames* pDrv = p.mf_pGetDriverNames();
if( pDrv->mf_nGetNumItems() == 0 )  //no asio drivers found
    return 0;
  
  //open first driver found
if( p.mf_bOpenDriver( pDrv->mf_GetItem( 0 ), c_lSampleRate, c_nBufferSize, c_nChannels, c_nChannels, &myData, &pCallback ) )
{
  myData.Init( &p, 2.0 );
  p.mf_bStart();
  Sleep( 5000 );
  p.mf_bStop();
}
delete pDrv;

files (includes container classes used):
http://users.skynet.be/parklife/asiowsrc.rar

code comes without any warranty but may be used and modified to taste ;-]
It's only a minor part of a bigger framework for dsp, and it's not completely finished, eg only returns 16bit, lack of decent error checking,..
I have succesfully tested the code on 3 soundcards (LynxONE, Rme Multiface, MAuddio Audiophile), but I'm not sure it works for any asio driver.
Let me know something when it's usefull/you find bugs/.. !

Greetz!