WAVEHDR structure
The WAVEHDR structure defines the header used to identify a waveform-audio buffer.
Syntax
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, specifies how much data is in the buffer.dwUser
User data.dwFlags
A bitwise OR of zero of more flags. The following flags are defined:Name Description 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
Minimum supported client |
Windows 2000 Professional [desktop apps only] |
Minimum supported server |
Windows 2000 Server [desktop apps only] |
Header |
Mmsystem.h (include Windows.h) |