JEITA CP-3451
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The meaning of each member of the format information is given in Table 22.
Table 22 Format Information Members
Member
Description
wFormatTag
An unsigned 16-bit integer indicating the format type (audio coding format) of the
WAVE Form. Typical format types are given below.
PCM (Pulse Code Modulation) format: 0001.H
m-Law format (ITU-T G.711): 0007.H
IMA-ADPCM (DVI-ADPCM) format: 0011.H
nChannels
An unsigned 16-bit integer indicating the number of channels. Monaural is 1 and
stereo is 2.
nSamplesPerSec
An unsigned 32-bit integer indicating the sampling rate (samples per second). Audio
is played in each channel at this rate.
In PCM format the common values of this member are 8.0kHz, 11.025kHz,
22.05kHz, and 44.1kHz.
nAvgBytesPerSec
An unsigned 32-bit integer indicating the average bytes per second, a value
transferred to the data in data-ck.
In PCM format, nAvgBytesPerSec is equivalent to the equation below.
nChannels * wBitsPerSample/8
nBlockAlign
An unsigned 16-bit integer indicating the (byte unit) block alignment in data-ck. In
PCM format, nBlockAlign is equivalent to the equation below.
nChannels * wBitsPerSample/8
wBitsPerSample
An unsigned 16-bit integer indicating the bits per sample of each channel.
In PCM format, this value is 8 or 16.
In the case of compressed sound data, when this value cannot be defined it
becomes '0'.
cbSize
An unsigned 16-bit integer indicating the size (in bytes) of the additional format
information extByte[cbSize] appended after the WAVEFORMATEX structure. This
information is used to store attributes added in non-PCM formats. If additional
information is not needed, it becomes '0'.
In PCM format, this member is not needed (the cbSize field itself is not necessary).
extByte[cbSize]
A byte array representing the additional format information appended after the
WAVEFORMATEX structure.
The meaning of this information depends on the format type. If the value of cbSize is
0, this field does not exist.
In PCM format, both the cbSize field and extByte[cbSize] field are unnecessary.