AN2394

.WAV file format

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.WAV file format

The .WAV file format is a subset of the Resource Interchange File Format (RIFF)

specification used for the storage of multimedia files. A RIFF file starts with a file header

followed by a sequence of data chunks. A .WAV file is often just a RIFF file with a single

"WAVE" chunk consisting of two sub-chunks:

1.

a fmt chunk specifying the data format

2.

a data chunk containing the actual sample data.

The numerical format used is Little-Endian (least significant byte first) and Big-Endian (most

significant byte first) order.

The WAVE file format starts with the RIFF header:

Endian

Offset

Length

Contents

big

0

4 bytes

'RIFF'

// 0x52494646

little

4

4 bytes

<file length - 8>

big

8

4 bytes

'WAVE'

// 0x57415645

Next, the fmt chunk describes the sample format:

big

12

4 bytes

'fmt '

// 0x666D7420

little

16

4 bytes

0x00000010

// Length of the fmt data (16 bytes)

little

20

2 bytes

0x0001

// Format tag: 1 = PCM

little

22

2 bytes

<channels>

// Channels: 1 = mono, 2 = stereo

little

24

4 bytes

<sample rate>

// Samples per second: e.g., 22050

little

28

4 bytes

<bytes/second> // sample rate * block align

little

32

2 bytes

<block align>

// channels * bits/sample / 8

little

34

2 bytes

<bits/sample>

// 8 or 16

Finally, the data chunk contains the sample data:

big

36

4 bytes

'data'

// 0x64617461

little

40

4 bytes

<length of the data block>

little

44

*

<sample data>

This application assumes that the .WAV file to be played has the following format:

●

Audio Format: PCM (an uncompressed wave data format in which each value

represents the amplitude of the signal at the time of sampling.)

●

Sample rate: may be 8000, 11025, 22050 or 44100 Hz.

●

Bits Per Sample: 8-bit (Audio sample data values are in the range [0-255] ).

●

Number Of Channels: 1 (Mono)