Wave file format

WAV files use the RIFF file structure. The RIFF format was designed for multi-media purposes. A RIFF files consists of a number of "chunks":

Offset	Label	Length	Description
00h	rID	4h	Contains the characters "RIFF"
04h	rLen	4h	The length of the data in the next chunk
08h	rData	rLen	The data chunk

The WAVE form chunk
The rData chunk in a WAV file is split up into several further chunks:
of the Data in the Data Chunk

rData byte offset	Label	Length	Description
00h	wID	4h	Contains the characters "WAVE"
04h	Format Chunk	14h	Contains data which specifies the format
18h	WAVE Data Chunk	-	Contains the WAV audio data

The format chunk
The Windows .WAV files are RIFF format files. Some programs expect the fmt block right behind the RIFF header itself, so your programs should write out this block as the first block in the RIFF file. Note the space in the id string

The Format Chunk is split up into these fields:

Format Chunk Offset	Label	Length	Description
00h	fId	4	Contains the characters "fmt "
04h	fLen	4	Length of data in the format chunk
08h	wFormatTag	2	The wFormatTag specifies the wave format, eg 1 = Pulse Code Modulation (or in plain english, regular 8 bit sampled uncompressed sound)
0Ah	nChannels	2	Number of channels, 1=mono, 2=stereo
0Ch	nSamplesPerSec	2	Playback frequency (Sample Rate)
0Eh	nAvgBytesPerSec	2	Indicates the average number of bytes a second the data should be transferred at = nChannels * nSamplesPerSec * (nBitsPerSample / 8)
10h	nBlockAlign	2	Indicates the block alignment of the data in the data chunk. Software needs to process a multiplt of nBlockAlign at a time. nBlockAlign = nChannels * (nBitsPerSample / 8)
12h	FormatSpecific	2	Format specific data area

The Data chunk
The Data Chunk is split up into these fields:

Data Chunk Offset	Label	Length	Description
00h	dId	4	Contains the characters "data"
02h	dLen	4	Length of data in the dData field
00h	dData	dLen	The actual waveform data

For example, if the file is a mono, 8-bit file, each byte represents one sample. In stereo 8-bit files two bytes are stored for each sample, the first byte is the left channel value, the next is the right channel value.

The loop chunk
Im not sure if this is an official block type but it is used to specify a sample that is repeated.

loop chunk offset	length	description
00h	1	Start of sample loop
04h	1	End of sample loop