The wavemix DLL is a utility that allows multiple wav files to be played
simultaneously. It is designed to be as simple to use as possilbe but still
have the power to do what is required by games.  The DLL supports 8 channels
of simultaneous wave play, the ability to queue up waves along the same
channel and wave completion notification.

The wavemix DLL currently supports 11.025 Khz, 22.05 Khz and 44.1 Khz 8-bit Mono and Stereo.
Wave conversion from the file format is done automatically to the output sampling rate
when the file is opened.  The default sampling rate is set in wavemix.ini.  See wavemix.ini for
details.  16 bit files are converted to 8-bit when the wave is loaded.

The API consists of the following functions:

HANDLE WINAPI WaveMixInit(void);
HANDLE WINAPI WaveMixConfigureInit(LPMIXCONFIG lpConfig);
HANDLE WINAPI WaveMixActivate(HANDLE hMixSession, BOOL fActivate);
LPMIXWAVE WINAPI WaveMixOpenWave(HANDLE hMixSession, LPSTR szWaveFilename, HINSTANCE hInst, DWORD dwFlags);
UINT WINAPI WaveMixOpenChannel(HANDLE hMixSession, int iChannel, DWORD dwFlags);
UINT WINAPI WaveMixPlay(LPMIXPLAYPARAMS lpMixPlayParams);
UINT WINAPI WaveMixFlushChannel(HANDLE hMixSession, int iChannel, DWORD dwFlags);
UINT WINAPI WaveMixCloseChannel(HANDLE hMixSession, int iChannel, DWORD dwFlags);
UINT WINAPI WaveMixFreeWave(LPMIXWAVE lpMixWave);
UINT WINAPI WaveMixCloseSession(HANDLE hMixSession);
void WINAPI WaveMixPump(void);
WORD WINAPI WaveMixGetInfo(LPWAVEMIXINFO lpWaveMixInfo);

In order to play a file a program must: 
1. Initialize the DLL with WaveMixInit() or WaveMixConfigureInit()
2. Open a wave file with WaveMixOpenFile()
3. Open a channel with WaveMixOpenChannel()
4. Call WaveMixActivate(TRUE) to tell wavemix.dll to actually get the wave output device (see note 1 below)
5. Play the file using WaveMixPlay()

A given channel can be silenced by calling WaveMixFlushChannel() at any time.

When the program is done with playing sounds it should

1. Close the open channels using WaveMixCloseChannel()
2. Free the memmory for the waves using WaveMixFreeWave()
3. End the session with WaveMixCloseSession()

Note 1:
An appliction should call WaveMixActivate(FALSE) when it loses the focus so that
the waveform device can be freed for other applications.  When focus is regained
the application can call WaveMixActivate(TRUE);

Note 2:
An application that does not release the processor can cause the sound to "skip"
To avoid this it can call WaveMixPump() frequently.

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WORD WINAPI WaveMixGetInfo(LPWAVEMIXINFO lpWaveMixInfo);

parameters

lpMixWaveMixInfo

	a pointer to a WAVEMIXINFO structure that will get filled in by the WaveMix DLL:

	typedef struct
	{
		WORD wSize;
		BYTE bVersionMajor;
		BYTE bVersionMinor;
		char szDate[12]; /* Mmm dd yyyy */
		DWORD dwFormats; /* see waveOutGetDevCaps (wavemix requires synchronous device) */
	}
	WAVEMIXINFO, *PWAVEMIXINFO, FAR * LPWAVEMIXINFO;

	wSize: should be set to sizeof(WAVEMIXINFO) before calling WaveMixGetInfo.

	bVersionMajor: the major version of the DLL.

	bVersionMinor: the minor version of the DLL.

	szDate: The compilation date of the DLL, Null terminated string in form Mmm dd yyyy
			where Mmm is one of the following:  "Jan","Feb","Mar","Apr","May","Jun","Jul","Aug",
			"Sep","Oct","Nov","Dec".

	dwFormats: Specifies which standard formats are supported. The supported formats are specified
			   with a logical OR of the flags listed in WAVEOUTCAPS documentation:

			   for version 1.0: the following wave formats are supported:

					WAVE_FORMAT_1M08  /* 11.025 kHz, Mono,   8-bit  */
					WAVE_FORMAT_1S08  /* 11.025 kHz, Stereo, 8-bit  */
					WAVE_FORMAT_1M16  /* 11.025 kHz, Mono,   16-bit */
					WAVE_FORMAT_1S16  /* 11.025 kHz, Stereo, 16-bit */
					WAVE_FORMAT_2M08  /* 22.05  kHz, Mono,   8-bit  */
					WAVE_FORMAT_2S08  /* 22.05  kHz, Stereo, 8-bit  */
					WAVE_FORMAT_2M16  /* 22.05  kHz, Mono,   16-bit */
					WAVE_FORMAT_2S16  /* 22.05  kHz, Stereo, 16-bit */
					WAVE_FORMAT_4M08  /* 44.1   kHz, Mono,   8-bit  */
					WAVE_FORMAT_4S08  /* 44.1   kHz, Stereo, 8-bit  */
					WAVE_FORMAT_4M16  /* 44.1   kHz, Mono,   16-bit */
					WAVE_FORMAT_4S16  /* 44.1   kHz, Stereo, 16-bit */

				this is done by converting the wave format of the input wave to the current
				output format when the wave is opened.

return value

zero will be returned if the size fields match and the structure will be filled in.

if the size fields do not match the DLL will return the size that it expected.  None of the fields
in the structure will be filled in.

-------------------------------------------------------------------------------

HANDLE WINAPI WaveMixInit(void);

This function should be called before any of the other functions.  It will return
a handle that should be used for subsequent API calls.  This function will conifgure
the DLL using default parameters and parameters specified in wavemix.ini

Note: WaveMixConfigureInit is a replacement for this function it provides application

Parameters

none

Return Value

NULL will be returned if an error occurs

-------------------------------------------------------------------------------

HANDLE WINAPI WaveMixConfigureInit(LPMIXCONFIG lpConfig);

Applications that require more control over the DLL should call this function instead
of WaveMixInit().  It allows the application to specify if the DLL should support
stereo output and allows the application to specify the sampling rate.  It is likely
that more parameters will be specified in the future.

Note: This function is a replacement to WaveMixInit(), only one of them should be called.
 
Parameters

lpConfig

	a pointer to a MIXCONFIG structure:

	#define WMIX_CONFIG_CHANNELS 0x1
	#define WMIX_CONFIG_SAMPLINGRATE 0x2
	typedef struct
	{
		WORD wSize;
		DWORD dwFlags;
		WORD wChannels;  /* 1 = MONO, 2 = STEREO */
		WORD wSamplingRate; /* 11,22,44  (11=11025, 22=22050, 44=44100 Hz) */
	}
	MIXCONFIG, *PMIXCONFIG, FAR * LPMIXCONFIG;

	wSize: should be set to sizeof(MIXCONFIG)

	dwFlags: this parameter is the bitwise OR of the parameters the application
			 wishes to specify.

	wChannels: The number of output channels to use 1 = MONO, 2 = STEREO
			 you must bitwise or dwFlags with WMIX_CONFIG_CHANNELS when you
			 set this parameter

	wSamplingRate: the output sampling rate you want to play at.  This parameter
			can be set to 11, 22, or 44.  You must also bitwise OR dwFlags with
			WMIX_CONFIG_SAMPLINGRATE.

			Note: It is a good idea not to set this parameter.  That will permit
			wavemix to use the value that has been specified in wavemix.ini

Return Value

NULL will be returned if an error occurs

-------------------------------------------------------------------------------

UINT WINAPI WaveMixActivate(HANDLE hMixSession, BOOL fActivate);

This function should be called when an application loses the focus or otherwise
becomes inactive.  This will permit other applications to aquire the wave output
device. Calling this function keeps all the channels open.

Note:

1. The wavemix DLL will keep sounds that were queued while the application was
active in the queue.  When wavemix play is subsequently reactivated the sounds will
continue from where they were.  (there will be a small amount of data loss equivalent
to the amount of data that was buffered in the wave driver).  

2. Calls to WaveMixPlay that are made while the application is not active will not be queued.

3. The Application can call WaveMixFlush if it does not wish the data to be pending while
it is inactive.

Parameters

HANDLE hMixSession

handle that was returned by WaveMixInit()

BOOL fActivate

	TRUE:  The application is being activated and wishes to regain the wave output
		   device
	FALSE: The application is not active and wishes to be a good Windows Citizen and
	       allow other applications to use the wave output device.  This call will
		   cause all the channels to be flushed.

Return Value

Returns zero if the function was successful. Otherwise, it returns an error
number. Possible error returns are:

MMSYSERR_ALLOCATED

Specified resource is already allocated to a process. try again later.

MMSYSERR_NOMEM

Unable to allocate or lock memory.

MMSYSERR_ERROR

an internal error

-------------------------------------------------------------------------------

LPMIXWAVE WINAPI WaveMixOpenWave(HANDLE hMixSession, LPSTR szWaveFilename,
								 HINSTANCE hInst, DWORD dwFlags);

Parameters

HANDLE hMixSession

handle that was returned by WaveMixInit()

LPSTR  szWaveFileName

szWaveFileName can be the name of a wave file to open, or the name of a WAVE resource
to open, or an integer ID of a WAVE resource to open.  See the dwFlags parameter for
details

HINSTANCE hInst

Identifies the instance of the module whose executable file contains the resource.
See the dwFlags parameter for details.

DWORD dwFlags

	WMIX_FILE: if this bit is set then szWaveFileName specifies a far pointer to a
			   string containing the filename of the file to open.  hInst is ignored.

			   The MS-DOS filename should not be longer than 128 bytes, including the
			   terminating NULL.

			   Currently the DLL will only permit 11Khz 8-bit mono files to be opened.

			   This flag should not be set with WMIX_RESOURCE	

	WMIX_RESOURCE:  if this bit is set then szWaveFileName specifies a WAVE resource
			   to be opened in hInst.

			   If the high-order word of the szWaveFileName is zero, the low-order word
			   specifies the integer identifier of the name or type of the given resource.
			   Otherwise, the parameter is a long pointers to a null-terminated string. If
			   the first character of the string is a pound sign (#), the remaining
			   characters represent a decimal number that specifies the integer identifier
			   of the resource's name or type. For example, the string #258 represents the
			   integer ID 258. 

			   To embed a wave file in a resource use the following format in your .rc file:
			   
			   GameSound WAVE gamesnd.wav

			   Note: to reduce the amount of memory required for the resources used by an
			   application, the application should refer to the resources by integer
			   identifier instead of by name.

Return Value

NULL will be returned if the dll was unable to open the file or resource.

-------------------------------------------------------------------------------

UINT WINAPI WaveMixOpenChannel(HANDLE hMixSession, int iChannel, DWORD dwFlags);

Parameters

HANDLE hMixSession

handle that was returned by WaveMixInit()

int iChannel

Specifies a number which indicates which channel should be opened.  Currently 
the DLL supports channels 0 though 7.

It is not necessary to open or close them in any particular order.

DWORD dwFlags
	WMIX_OPENSINGLE: iChannel specifies the single channel to be opened.
	WMIX_ALL:	all the available channels will be opened. iChannel is ignored.
	WMIX_OPENCOUNT: iChannel specifies the number of channels to open.  
			   eg. if iChannel==4 then channels 0 through 3 will be opend.


Return Value

Returns zero if the function was successful. Otherwise, it returns an error
number. Possible error returns are:

MMSYSERR_INVALHANDLE

if an invalid channel (ie > 7) was specified

MMSYSERR_BADDEVICEID

Specified device ID is out of range.

MMSYSERR_ALLOCATED

Specified resource is already allocated.
Or the channel has already been opened.

MMSYSERR_NOMEM

Unable to allocate or lock memory.

WAVERR_BADFORMAT

Attempted to open with an unsupported wave format.

WAVERR_SYNC

Attempted to open a synchronous driver without specifying the WAVE_ALLOWSYNC flag.

MMSYSERR_ERROR

an internal error

-------------------------------------------------------------------------------

UINT WINAPI WaveMixPlay(LPMIXPLAYPARAMS lpMixPlayParams);

parameters

lpMixPlayParams

	a pointer to a MIXPLAYPARAMS structure:

	typedef struct
	{
		WORD wSize;
		HANDLE hMixSession;
		int iChannel;
		LPMIXWAVE lpMixWave;
		HWND hWndNotify;
		DWORD dwFlags;
		WORD wLoops;  /* 0xFFFF means loop forever */
	}
	MIXPLAYPARAMS, * PMIXPLAYPARAM, FAR * LPMIXPLAYPARAMS;

	wSize: should be set to sizeof(MIXPLAYPARAMS)

	hMixSession: the handle that was returned by WaveMixInit()

	iChannel: the channel on which the wave should be played.

	lpMixWave: a wave which was opened using WaveMixOpenWave()

	hWndNotify: a window handle to receive the MM_WOM_DONE message
		when the wave completes.  If this value is set to NULL then
		the message will not be posted.

	dwFlags: WMIX_QUEUEWAVE: the wave will be placed on the specified channel
							 and played after all waves which are currently
							 waiting to play on that channel.
	         WMIX_CLEARQUEUE:this wave will preempt all waves currently playing
			 				 on the specified channel.  Notification messages
							 will not be sent for any waves that get dumped.
							 This message should not be combined with WMIX_QUEUEWAVE
			 WMIX_HIGHPRIORITY: Play this way immediately.  This flag will interrupt
							 the data buffered in the wave driver and remix the sound.
							 If this flag is not set you could experience up to a half
							 second delay before sound is played.

							 Note: if WMIX_QUEUEWAVE is set with this flag then a sound
							 playing on the channel will not be prempted, but it will
							 begin immediately after the previous sound finishes.  If no
							 sound is currently playing on this channel then a remix will
							 occur.
							 
	         WMIX_USELRUCHANNEL: the wave should be played on any available channel
							 or played on the channel that was least recently used.
							 This flag should be combined with WMIX_QUEUEWAVE or
							 WMIX_CLEARQUEUE.

			WMIX_WAIT:		 setting this flag cause waveMixPlay to put the play information on
							 a "waiting list" to play.  when waveMixPlay is called without this
							 flag set it will process the calls in the order they were received.
							 This is useful if you want to play multiple sounds simultaneously.

							 Note 1: This flag is not a 'pause'.  Waves that are playing will continue
							 to play regardless of how many files are on the wait list.

							 Note 2: Since the waves that are submitted with this flag set are not
							 checked until waveMixPlay is called without the flag set you should
							 be careful about using other API calls before playing the sounds.
							 eg. WaveMixFlushChannel and WaveMixCloseChannel do not process the
							 wait list.

	wLoops: The number of times the wave should be repeated.  If dwLoops is set to 
			0xFFFF the wave will loop until the channel it is on is flushed, preempted,
			or closed.

Return Value

Returns zero if the function was successful. Otherwise, it returns an error
number. Possible error returns are:

MMSYSERR_INVALHANDLE

The specified channel has not been opened or invalid lpMixWave was passed in

MMSYSERR_NOMEM

The dll has run out of internal memory to queue up waves.  Wait until some 
sounds complete and then try again.

-------------------------------------------------------------------------------

UINT WINAPI WaveMixFlushChannel(HANDLE hMixSession, int iChannel, DWORD dwFlags);

This function will empty the queue of any waves waiting to play on this channel.
This function can be called to stop a wave that is playing on the channel without
affecting any of the other channels.

Parameters

HANDLE hMixSession

The handle that was returned by WaveMixInit()

int iChannel

an integer which specifies a previously opened channel

DWORD dwFlags
													 
	WMIX_ALL: causes all the channels to be flushed. iChannel is ignored.
	WMIX_NOREMIX: prevents WaveMixFlushChannel from causing the data to be
				  immediately remixed.  This is useful if you want to flush
				  more than one channel, or if you will be calling WaveMixPlay
				  with a HIPRIORITY wave following WaveMixFlushChannel

Return Value

Returns zero if the function was successful. Otherwise, it returns an error
number. Possible error returns are:

MMSYSERR_INVALHANDLE

The specified channel was not open

MMSYSERR_INVALPARAM

One of the parameters passed to the function is not valid

-------------------------------------------------------------------------------

UINT WINAPI WaveMixCloseChannel(HANDLE hMixSession, int iChannel, DWORD dwFlags);

This function will flush and close the specified channel.

Parameters

HANDLE hMixSession

The handle that was returned by WaveMixInit()

int iChannel

an integer which specifies a previously opened channel

DWORD dwFlags
													 
	WMIX_ALL: causes all the channels to be flushed. iChannel is ignored.

Return Value

Returns zero if the function was successful. Otherwise, it returns an error
number. Possible error returns are:

MMSYSERR_INVALHANDLE

The specified channel was not open

-------------------------------------------------------------------------------

UINT WINAPI WaveMixFreeWave(HANDLE hMixSession, LPMIXWAVE lpMixWave);

Parameters

HANDLE hMixSession

The handle that was returned by WaveMixInit()

lpMixWave

A pointer that was created by WaveMixOpenWave()

Return Value

Returns zero if the function was successful. Otherwise, it returns an error
number. Possible error returns are:

MMSYSERR_INVALHANDLE

The given pointer was not valid

-------------------------------------------------------------------------------
UINT WINAPI WaveMixCloseSession(HANDLE hMixSession);

This function pairs up with WaveMixInit().  It should be called before the 
application terminates.

Parameters

HANDLE hMixSession

The handle that was returned by WaveMixInit()

Return Value

Returns zero if the function was successful. Otherwise, it returns an error
number. Possible error returns are:

MMSYSERR_INVALHANDLE

The given handle was not a valid session

-------------------------------------------------------------------------------

void WINAPI WaveMixPump(void);

Calling this function causes the WaveMix DLL to mix the next slice of wave data
and submit it to the wave drivers.  This function can be called if the application
does a lot of processing and fails to allow messages to reach the WaveMix DLL in 
time to avoid drying up the wave queue.

Parameters

none

Return Value

none

-------------------------------------------------------------------------------









