CWaveForm

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Introduction

This wrapper class implements standard waveform APIs in object oriented way. It supports following features :

• Supports both wave_in and wave_out object in one class. You can indicate which type of stream to use by setting Direction.
• Use my own private stream device interface to abstract the real world stream behavior. This  interface is still under development.
• All memory allocation and deallocation is managed by theobject itself. That is, the caller never worries about memory. This is achieved by using IIDataSource & IIDataSink interface defined by myself.
• The use of callback functions instead of callback windows. This is especially suitable for drawing intensive programs.
• The use of the private IIAdvise interface, through which you can notify the client by window, thread ID, event and callback function. Very flexible. In my own project I use a separate thread to process the wave data.
• Support volume control on wave_in and wave_out stream.
• The use of AddRef()/Release() to manage the object life cycle. (Similar to COM)

The package includes three files. 

• CWaveForm.cpp
• CWaveForm.h
• Interface.h

How to use my classes:

1. Create a wave object 

   new CWaveForm(...)

   This contractor has couples parameters. Stream direction (in or out), wave in device id, wave out device id, wave in format, wave out format, wave in volume, wave out volume. Remember to call AddRef()

2. Wave device operation sequence : open()->start()->stop()->close().
3. Whenever wave in data is incoming, the object itself will invoke, that is, callback to the client. Then client calls the Read(ppData) function to get data buffer. After processing, client calls ReadDone(pData) to return data buffer.
4. Whenever the client wants to send data to the wave out device, it can call Write() twice. The first call should provides an empty pointer, which will be filled with a valid buffer address. Then the client can write any data to this buffer, then call Write() again to queue this buffer back to wave out object.
5. Please call Release() to free wave object.

Example

1. Create new wave object:

   WaveForm = new CWaveForm
   (
   	WAVE_FORM_FLOW_BOTH, // Support both WAVE_IN and WAVE_OUT
   	m_waveInDeviceID,
   	m_waveOutDeviceID,
   	&m_waveInFormatEx,
   	&m_waveOutFormatEx,
   	m_waveInVolume,
   	m_waveOutVolume
   );
   
   WaveForm->AddRef(); // For wave_in.
   WaveForm->AddRef(); // For wave_out.

2. Client advises call back interface:

   WaveForm->Advise
   (
   (DWORD)m_hThread, // I use seperate THREAD to processing wave data.
   0, // dwInstance is 0
   WM_STREAM_NOTIFY, // My private window message mask
   CALLBACK_THREAD // Callback type.
   );
   

3. Whenever wave in data is coming:

   // Notify client.
   Invoke(WM_STREAM_NOTIFY, SUB_EVENT_WAVE_IN, 0);

4. Client reading data:
   

   PWAVEFRAME pWaveFrame;
   WaveForm->Read(&pWaveFrame); // Get wave in data.
   .
   .
   // Client processing wave in data.
   .
   .
   WaveForm->ReadDone(pWaveFrame); // Return wave in data.

5. Client write data to wave out device:

   PWAVEFRAME pWaveFrame = NULL;
   WaveForm->Write(&pWaveFrame); // Ask wave out object to allocate memory.
   .
   .
   // Client fill up this buffer with any data.
   .
   .
   WaveForm->Write(pWaveFrame); // Write data to wave out device.

6. After using wave object:

   WaveForm->Release(); // For wave_in.
   WaveForm->Release(); // For wave_out.