This function opens a specified waveform input device for recording.
At a Glance
| Header file: | Mmsystem.h |
| Windows CE versions: | 2.0 and later |
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
Identifier of the waveform-audio input device to open. It can be either a device identifier or a Handle to an open waveform-audio input device. 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_NOERROR | Success. |
| 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. |
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.
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.