_WAVEFORMATEX
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The _WAVEFORMATEX structure defines the format of waveform-audio data.
Syntax
typedef struct _tWAVEFORMATEX{WORD wFormatTag;WORD nChannels;DWORD nSamplesPerSec;DWORD nAvgBytesPerSec;WORD nBlockAlign;WORD wBitsPerSample;WORD cbSize;
} _WAVEFORMATEX;
Members
wFormatTag
Must be set to a format or formats supported by the device. Note that previous versions of the Windows Media Device Manager recommended using WMDM_WAVE_FORMAT_ALL to indicate support for all formats. However, this is no longer recommended, as different media players will interpret this in different ways, and few devices can truly play any file format. It is now recommended that you use the WMDM_ENUM_PROP_VALID_VALUES_ANY value of the WMDM_ENUM_PROP_VALID_VALUES_FORM enumeration, or—better yet—specify a range of formats with the WMDM_PROP_VALUES_RANGE structure.
nChannels
Number of channels in the waveform-audio data. Monaural data uses one channel, and stereo data uses two channels.
nSamplesPerSec
Sample rate, in samples per second (Hertz), at which each channel must be played or recorded. Common values for nSamplesPerSec are 8.0 kilohertz (kHz), 11.025 kHz, 22.05 kHz, and 44.1 kHz.
nAvgBytesPerSec
Required average data-transfer rate for the format tag, in bytes per second. Playback and recording software can estimate buffer sizes by using the nAvgBytesPerSec member.
nBlockAlign
Block alignment, in bytes. The block alignment is the minimum atomic unit of data for the wFormatTag format type. Playback and recording software must process a multiple of nBlockAlign bytes of data at a time. Data written and read from a device must always start at the beginning of a block. For example, it is not possible to correctly start playing PCM data in the middle of a sample (that is, on a boundary that is not block aligned).
wBitsPerSample
Bits per sample for the wFormatTag format type.
cbSize
This member is ignored.
Requirements
Header: Defined in wmdm.idl.
Library: mssachlp.lib
See Also