WAVEHDR

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Windows Embedded CE 6.0 R3

4/8/2010

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

Syntax

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

Members

• lpData
  Long pointer to the address of the waveform buffer. This buffer must be block-aligned according to the nBlockAlign member of the WAVEFORMATEX structure used to open the device.

• dwBufferLength
  Specifies the length, in bytes, of the buffer.

• dwBytesRecorded
  When the header is used in input, this member specifies how much data is in the buffer. When the header is used in output, this member specifies the number of bytes played from the buffer.

• dwUser
  Specifies user data.

• dwFlags
  Specifies information about the buffer. The following table shows the possible values.

  Value	Description
  WHDR_BEGINLOOP	Set this flag when the buffer should be looped during playback. If you set this flag, you must also set WHDR_ENDLOOP. 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	Set this flag when the buffer should be looped during playback. If you set this flag, you must also set WHDR_BEGINLOOP. 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
  Specifies the number of times to play the loop. This member is used only with output buffers.

• lpNext
  Reserved. This member is used within the audio driver to maintain a first-in, first-out linked list of headers awaiting playback.

• 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

See Also

Reference

Waveform Audio Structures
WAVEFORMATEX (Waveform Audio)