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Posted 13 Feb 2009

Multidevice ASIO output plugin for WinAMP

, 13 Feb 2009
A tiny WinAMP output DLL that uses a C++ replacement of the official ASIO SDK that supports multiple ASIO devices.
#pragma once

#include "WinAMP.hpp"

namespace WinAMP

namespace OutModule

extern "C"

//  Out_Module
//  ----------
//  A workaround copy-paste redefinition of the Out_Module struct from the out.h
// WA SDK header that only adds the __cdecl specifiers to enable compiling with
// a default global calling convention different from cdecl.
// (todo) try to think of something better.
//#include "WA SDK/Winamp/OUT.H"

#define OUT_VER 0x10

struct Out_Module
	int version;				// module version (OUT_VER)
	char *description;			// description of module, with version string
	intptr_t id;						// module id. each input module gets its own. non-nullsoft modules should
								// be >= 65536. 

	HWND hMainWindow;			// winamp's main window (filled in by winamp)
	HINSTANCE hDllInstance;		// DLL instance handle (filled in by winamp)

	void (__cdecl *Config)(HWND hwndParent); // configuration dialog 
	void (__cdecl *About)(HWND hwndParent);  // about dialog

	void (__cdecl *Init)();				// called when loaded
	void (__cdecl *Quit)();				// called when unloaded

	int (__cdecl *Open)(int samplerate, int numchannels, int bitspersamp, int bufferlenms, int prebufferms); 
					// returns >=0 on success, <0 on failure

					// NOTENOTENOTE: bufferlenms and prebufferms are ignored in most if not all output plug-ins. 
					//    ... so don't expect the max latency returned to be what you asked for.
					// returns max latency in ms (0 for diskwriters, etc)
					// bufferlenms and prebufferms must be in ms. 0 to use defaults. 
					// prebufferms must be <= bufferlenms
					// pass bufferlenms==-666 to tell the output plugin that it's clock is going to be used to sync video
					//   out_ds turns off silence-eating when -666 is passed

	void (__cdecl *Close)();	// close the ol' output device.

	int (__cdecl *Write)(char *buf, int len);	
					// 0 on success. Len == bytes to write (<= 8192 always). buf is straight audio data. 
					// 1 returns not able to write (yet). Non-blocking, always.

	int (__cdecl *CanWrite)();	// returns number of bytes possible to write at a given time. 
						// Never will decrease unless you call Write (or Close, heh)

	int (__cdecl *IsPlaying)(); // non0 if output is still going or if data in buffers waiting to be
						// written (i.e. closing while IsPlaying() returns 1 would truncate the song

	int (__cdecl *Pause)(int pause); // returns previous pause state

	void (__cdecl *SetVolume)(int volume); // volume is 0-255
	void (__cdecl *SetPan)(int pan); // pan is -128 to 128

	void (__cdecl *Flush)(int t);	// flushes buffers and restarts output at time t (in ms) 
							// (used for seeking)

	int (__cdecl *GetOutputTime)(); // returns played time in MS
	int (__cdecl *GetWrittenTime)(); // returns time written in MS (used for synching up vis stuff)


//  Forward declarations of WinAMP output module callbacks. Implementations must
// be provided by the concrete output plugin module.
void __cdecl Init        ();
void __cdecl Quit        ();

int  __cdecl Open        ( int sampleRate, int numChannels, int BPS, int bufferLen_ms, int prebuffer_ms );
void __cdecl Close       ();

int  __cdecl IsPlaying   ();
int  __cdecl Pause       ( int pause  );

int  __cdecl CanWrite    ();
int  __cdecl Write       ( char * buf, int len );

void __cdecl SetVolume   ( int volume  );
void __cdecl SetPan      ( int pan     );
void __cdecl Flush       ( int time_ms );

int  __cdecl GetWrittenTime();
int  __cdecl GetOutputTime ();

void __cdecl ConfigDialog( HWND hwnd );
void __cdecl About       ( HWND hwnd );


//  Functions for automatic filling of the WinAMP output module Out_Module
// structure. Must be implemented by the concrete output module plugin.
char const * WAOutModuleDescription();
intptr_t     WAOutModuleID();

// Compile time configuration.
static size_t const maxWAInputChunk = 8192; // As specified by an out.h comment.

//  WAOutModule
//  -----------
//  A wrapper around the Out_Module struct that fills it automatically and
// provides methods to change/configure some of the callbacks at runtime as well
// as some default implementations for those same callbacks.

class WAOutModule : private Out_Module
    static WAOutModule & singleton();

    Out_Module & getWAOutModule() { return *this; }

    HWND      WinAMPWindow() const { assert( hMainWindow  && "WinAMP didn't fill in it's window handle!"      ); return hMainWindow ; }
    HINSTANCE DLLInstance () const { assert( hDllInstance && "WinAMP didn't fill in the DLL instance handle!" ); return hDllInstance; }

    // Configurable callbacks.
    typedef int  (__cdecl *WriteCallback    )( char * buf, int len );
    typedef void (__cdecl *SetVolumeCallback)( int volume          );
    typedef void (__cdecl *SetPanCallback   )( int pan             );

    void setWriteCallback    ( WriteCallback     writeCallback     ) { Write     = writeCallback    ; }
    void setSetVolumeCallback( SetVolumeCallback setVolumeCallback ) { SetVolume = setVolumeCallback; }
    void setSetPanCallback   ( SetPanCallback    setPanCallback    ) { SetPan    = setPanCallback   ; }

    // Default callback implementations.
    static void __cdecl SetVolumeMixer  ( int volume );
    static void __cdecl SetVolumeWaveOut( int volume );
    static void __cdecl SetVolumeVoid   ( int        ) {}

    static void __cdecl SetPanWaveOut( int pan );
    static void __cdecl SetPanMixer  ( int pan );
    static void __cdecl SetPanVoid   ( int     ) {}


    static WAOutModule WinAMPOutModule;

}   // namespace OutModule

}   // namespace WinAMP

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About the Author

Domagoj Šarić
Software Developer Little Endian Ltd.
Croatia Croatia
No Biography provided

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