PublicUtility/AUOutputBL.h

/*
     File: AUOutputBL.h 
 Abstract:  Part of CoreAudio Utility Classes  
  Version: 1.0 
  
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*/
#ifndef __AUOutputBL_h__
#define __AUOutputBL_h__
 
#include "CAStreamBasicDescription.h"
#if !defined(__COREAUDIO_USE_FLAT_INCLUDES__)
#else
#endif
 
// ____________________________________________________________________________
//
//  AUOutputBL - Simple Buffer List wrapper targetted to use with retrieving AU output
// Works in one of two ways (both adjustable)... Can use it with NULL pointers, or allocate
// memory to receive the data in.
 
// Before using this with any call to AudioUnitRender, it needs to be Prepared
// as some calls to AudioUnitRender can reset the ABL
 
class AUOutputBL {
public:
                                            
                                            // you CANNOT use one of these - it will crash!
//                                      AUOutputBL ();
                                        
                                            // this is the constructor that you use
                                            // it can't be reset once you've constructed it
                                        AUOutputBL (const CAStreamBasicDescription &inDesc, UInt32 inDefaultNumFrames = 512);
                                        ~AUOutputBL();
 
    void                                Prepare ()
                                        {
                                            Prepare (mFrames);
                                        }
                                    
                                // this version can throw if this is an allocted ABL and inNumFrames is > AllocatedFrames()
                                // you can set the bool to true if you want a NULL buffer list even if allocated
                                // inNumFrames must be a valid number (will throw if inNumFrames is 0)
    void                                Prepare (UInt32 inNumFrames, bool inWantNullBufferIfAllocated = false);
    
    AudioBufferList*                    ABL() { return mBufferList; }
                                
                                // You only need to call this if you want to allocate a buffer list
                                // if you want an empty buffer list, just call Prepare()
                                // if you want to dispose previously allocted memory, pass in 0
                                // then you either have an empty buffer list, or you can re-allocate
                                // Memory is kept around if an Allocation request is less than what is currently allocated
    void                                Allocate (UInt32 inNumberFrames);
    
    UInt32                              AllocatedFrames() const { return mFrames; }
    
    const CAStreamBasicDescription&     GetFormat() const { return mFormat; }
 
#if DEBUG
    void                                Print();
#endif
    
private:
    UInt32                      AllocatedBytes () const { return (mBufferSize * mNumberBuffers); }
 
    CAStreamBasicDescription    mFormat;
    Byte*                       mBufferMemory;
    AudioBufferList*            mBufferList;
    UInt32                      mNumberBuffers;
    UInt32                      mBufferSize;
    UInt32                      mFrames;
 
// don't want to copy these.. can if you want, but more code to write!
    AUOutputBL () {}
    AUOutputBL (const AUOutputBL &c);
    AUOutputBL& operator= (const AUOutputBL& c);
};
 
#endif // __AUOutputBL_h__