waveInOpen (Windows CE 5.0)

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This function opens a specified waveform input device for recording.



  • 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 Values

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

Value Description
MMSYSERR_ALLOCATED Specified resource is already allocated.
MMSYSERR_BADDEVICEID Specified device identifier is out of range.
MMSYSERR_NODRIVER No device driver is present.
MMSYSERR_NOMEM Unable to allocate or lock memory.
WAVERR_BADFORMAT 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.


OS Versions: Windows CE 2.0 and later.
Header: Mmsystem.h.
Link Library: Coredll.lib.

See Also

Waveform Audio Functions | waveInGetNumDevs | WAVEFORMATEX

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