waveOutOpen

The waveOutOpen function opens the given waveform-audio output device
for playback.
MMRESULT waveOutOpen(
LPHWAVEOUT phwo,
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UINT uDeviceID,
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LPWAVEFORMATEX pwfx,
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DWORD dwCallback,
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DWORD dwCallbackInstance,
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DWORD fdwOpen
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);
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Parameters
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phwo
-
Address filled with a handle identifying the open waveform-audio output
device. Use the handle to identify the device when calling other
waveform-audio output functions. This parameter might be NULL if the
WAVE_FORMAT_QUERY flag is specified for fdwOpen.
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uDeviceID
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Identifier of the waveform-audio output device to open. It can be either a
device identifier or a handle of an open waveform-audio input device.You can
use the following flag instead of a device identifier:
-
WAVE_MAPPER
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The function selects a waveform-audio output device capable of playing the
given format.
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pwfx
-
Address of a WAVEFORMATEX structure
that identifies the format of the waveform-audio data to be sent to the
device. You can free this structure immediately after passing it to waveOutOpen.
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dwCallback
-
Address of a fixed callback function, an event handle, a handle to a window,
or the identifier of a thread to be called during waveform-audio playback to
process messages related to the progress of the playback. If no callback
function is required, this value can be zero. For more information on the
callback function, see waveOutProc.
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dwCallbackInstance
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User-instance data passed to the callback mechanism. This parameter is not
used with the window callback mechanism.
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fdwOpen
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Flags for opening the device. The following values are defined:
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CALLBACK_EVENT
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The dwCallback parameter is an event handle.
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CALLBACK_FUNCTION
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The dwCallback parameter is a callback procedure address.
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CALLBACK_NULL
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No callback mechanism. This is the default setting.
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CALLBACK_THREAD
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The dwCallback parameter is a thread identifier.
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CALLBACK_WINDOW
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The dwCallback parameter is a window handle.
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WAVE_ALLOWSYNC
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If this flag is specified, a synchronous waveform-audio device can be opened.
If this flag is not specified while opening a synchronous driver, the device
will fail to open.
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WAVE_FORMAT_DIRECT
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If this flag is specified, the ACM driver does not perform conversions on the
audio data.
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WAVE_FORMAT_QUERY
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If this flag is specified, waveOutOpen queries the device to determine
if it supports the given format, but the device is not actually opened.
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WAVE_MAPPED
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If this flag is specified, the uDeviceID parameter specifies a
waveform-audio device to be mapped to by the wave mapper.
Return Values
Returns MMSYSERR_NOERROR if successful or an error otherwise. Possible error
values include the following:
MMSYSERR_ALLOCATED
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Specified resource is already allocated.
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MMSYSERR_BADDEVICEID
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Specified device identifier is out of range.
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MMSYSERR_NODRIVER
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No device driver is present.
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MMSYSERR_NOMEM
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Unable to allocate or lock memory.
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WAVERR_BADFORMAT
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Attempted to open with an unsupported waveform-audio format.
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WAVERR_SYNC
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The device is synchronous but waveOutOpen was called without using the
WAVE_ALLOWSYNC flag.
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Remarks
Use the waveOutGetNumDevs function
to determine the number of waveform-audio output devices present in the
system. If the value specified by the uDeviceID parameter is a device
identifier, it can vary from zero to one less than the number of devices
present. The WAVE_MAPPER constant can also be used as a device identifier.
The structure pointed to by pwfx can be extended to include
type-specific information for certain data formats. For example, for PCM data,
an extra UINT is added to specify the number of bits per sample. Use
the PCMWAVEFORMAT structure in this
case. For all other waveform-audio formats, use the WAVEFORMATEX
structure to specify the length of the additional data.
If you choose to have a window or thread receive callback information, the
following messages are sent to the window procedure function to indicate the
progress of waveform-audio output: MM_WOM_OPEN, MM_WOM_CLOSE, and MM_WOM_DONE.
If you choose to have a function receive callback information, the following
messages are sent to the function to indicate the progress of waveform-audio
output: WOM_OPEN, WOM_CLOSE, and WOM_DONE.
See Also
WAVEFORMATEX, waveOutGetNumDevs,
waveOutProc, PCMWAVEFORMAT,
MM_WOM_OPEN, MM_WOM_CLOSE,
MM_WOM_DONE
© 1997 Microsoft Corporation. All rights reserved. Legal Notices.