waveInOpen

A version of this page is also available for

Windows Embedded CE 6.0 R3

4/8/2010

This function opens a specified waveform input device for recording.

Syntax

MMRESULT waveInOpen(
  LPHWAVEIN phwi, 
  UINT uDeviceID, 
  LPCWAVEFORMATEX pwfx, 
  DWORD dwCallback, 
  DWORD dwInstance, 
  DWORD fdwOpen 
); 

Parameters

• phwi
  Address filled with a handle identifying the open waveform-audio input device. Use this handle to identify the device when calling other waveform-audio input functions. This parameter can be NULL if WAVE_FORMAT_QUERY is specified for fdwOpen.

• uDeviceID
  Device identifier of the waveform-audio input device to open. You can use the following flag instead of a device identifier.

  Value	Description
  WAVE_MAPPER	The function selects a waveform-audio input device capable of recording in the specified format.

• pwfx
  Pointer to a WAVEFORMATEX structure that identifies the desired format for recording waveform-audio data. You can free this structure immediately after waveInOpen returns.

• dwCallback
  Specifies the 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 recording to process messages related to the progress of recording. If no callback function is required, this value can be zero.

• dwInstance
  Specifies user-instance data passed to the callback mechanism. This parameter is not used with the window callback mechanism.

• fdwOpen
  Flags for opening the device. The following values are defined.

  Value	Description
  CALLBACK_EVENT	The dwCallback parameter is an event handle.
  CALLBACK_FUNCTION	The dwCallback parameter is a callback procedure address.
  CALLBACK_NULL	No callback mechanism. This is the default setting.
  CALLBACK_THREAD	The dwCallback parameter is a thread identifier.
  CALLBACK_WINDOW	The dwCallback parameter is a window handle.
  WAVE_FORMAT_DIRECT	If this flag is specified, the ACM driver does not perform conversions on the audio data.
  WAVE_FORMAT_QUERY	The function queries the device to determine whether it supports the specified format, but it does not open the device.
  WAVE_MAPPED	The uDeviceID parameter specifies a waveform-audio device to be mapped to by the wave mapper.

Return Value

One of the values described in the following table is returned.

Remarks

Use the waveInGetNumDevs function to determine the number of waveform-audio input devices present on the system. The device identifier specified by uDeviceID varies from zero to one less than the number of devices present. The WAVE_MAPPER constant can also be used as a device identifier.

If you choose to have a window or thread receive callback information, the following messages are sent to the window procedure or thread to indicate the progress of waveform-audio input: MM_WIM_OPEN, MM_WIM_CLOSE, and MM_WIM_DATA.

When waveInOpen opens an input stream, it places that stream in the stopped state. Capture will only begin after you have called waveInStart, this lets the driver know that your application is ready to begin capturing sound. If you have given the driver a buffer, through a prior call to waveInAddBuffer, then sound capture will begin immediately after the call to waveInStart. If the driver does not already have a buffer before the call to waveInStart, then sound capture will begin immediately after you provide it one using waveInAddBuffer.

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 input: WIM_OPEN, WIM_CLOSE, and WIM_DATA.

Requirements

See Also

Reference

Waveform Audio Functions
waveInGetNumDevs
WAVEFORMATEX (Waveform Audio)