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WAVEHDR

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The WAVEHDR structure defines the header used to identify a waveform-audio buffer.

typedef struct wavehdr_tag { 
    LPSTR      lpData; 
    DWORD      dwBufferLength; 
    DWORD      dwBytesRecorded; 
    DWORD_PTR  dwUser; 
    DWORD      dwFlags; 
    DWORD      dwLoops; 
    struct wavehdr_tag * lpNext; 
    DWORD_PTR reserved; 
} WAVEHDR, *LPWAVEHDR;

Members

lpData

Pointer to the waveform buffer.

dwBufferLength

Length, in bytes, of the buffer.

dwBytesRecorded

When the header is used in input, this member specifies how much data is in the buffer.

dwUser

User data.

dwFlags

Flags supplying information about the buffer. The following values are defined:

WHDR_BEGINLOOP

This buffer is the first buffer in a loop.  This flag is used only with output buffers.

WHDR_DONE

Set by the device driver to indicate that it is finished with the buffer and is returning it to the application.

WHDR_ENDLOOP

This buffer is the last buffer in a loop.  This flag is used only with output buffers.

WHDR_INQUEUE

Set by Windows to indicate that the buffer is queued for playback.

WHDR_PREPARED

Set by Windows to indicate that the buffer has been prepared with the waveInPrepareHeader or waveOutPrepareHeader function.

dwLoops

Number of times to play the loop. This member is used only with output buffers.

lpNext

Reserved.

reserved

Reserved.

Remarks

Use the WHDR_BEGINLOOP and WHDR_ENDLOOP flags in the dwFlags member to specify the beginning and ending data blocks for looping. To loop on a single block, specify both flags for the same block. Use the dwLoops member in the WAVEHDR structure for the first block in the loop to specify the number of times to play the loop.

The lpData, dwBufferLength, and dwFlags members must be set before calling the waveInPrepareHeader or waveOutPrepareHeader function. (For either function, the dwFlags member must be set to zero.)

Requirements

**  Windows NT/2000/XP:** Included in Windows NT 3.1 and later.
**  Windows 95/98/Me:** Included in Windows 95 and later.
**  Header:** Declared in Mmsystem.h; include Windows.h.

See Also

Waveform Audio, Waveform Structures, waveInPrepareHeader, waveOutPrepareHeader