RIFF Forms

A RIFF form is a chunk with a “RIFF” chunk ID. The term also refers to a file format that follows the RIFF framework. The following lists currently registered RIFF forms. Each is described later in this document.

Using the notation for representing a chunk, a RIFF form looks like the following:

RIFF ( <formType> <ck>... )

The first four bytes of a RIFF form make up a chunk ID with values `R' `I' `F' `F'. The chunk size (ckSize) field is required, but for simplicity it is omitted from the notation.

Note:

RIFF has a counterpart, RIFX, that you can use to define RIFF file formats that use the Motorola integer byte-ordering format rather than the Intel format. A RIFX form is the same as a RIFF form, except that the first four bytes contain the character sequence `R' `I' `F' `X' rather than RIFF. Integer byte ordering is represented in Motorola format.

The first DWORD of chunk data in the “RIFF” chunk (shown above as <formType>) is a four-character code value identifying the data representation, or form type, of the file. Following the form-type code is a series of subchunks. Which subchunks are present depends on the form type. The definition of a particular RIFF form typically includes the following:

A unique four-character code identifying the form type

A list of mandatory chunks

A list of optional chunks

Possibly, a required order for the chunks