Windows Mobile 6.5
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This function opens a specified waveform input device for recording.

MMRESULT waveInOpen(
  LPHWAVEIN phwi, 
  UINT uDeviceID, 
  DWORD dwCallback, 
  DWORD dwInstance, 
  DWORD fdwOpen 


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.


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

Value Description


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


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


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.


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


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

Value Description


The dwCallback parameter is an event handle.


The dwCallback parameter is a callback procedure address.


No callback mechanism. This is the default setting.


The dwCallback parameter is a thread identifier.


The dwCallback parameter is a window handle.


If this flag is specified, the ACM driver does not perform conversions on the audio data.


The function queries the device to determine whether it supports the specified format, but it does not open the device.


The uDeviceID parameter specifies a waveform-audio device to be mapped to by the wave mapper.

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

Value Description




Specified resource is already allocated.


Specified device identifier is out of range.


No device driver is present.


Unable to allocate or lock memory.


Attempted to open with an unsupported waveform-audio format.

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.

Windows Embedded CEWindows CE 2.0 and later
Windows MobileWindows Mobile Version 5.0 and later

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