Creating a RIFF Chunk
The following example uses the mmioCreateChunk function to create a chunk with a chunk identifier of "RIFF" and a form type of "RDIB".
HMMIO hmmio; MMCKINFO mmckinfo; . . . mmckinfo.fccType = mmioFOURCC('R', 'D', 'I', 'B'); mmioCreateChunk(hmmio, &mmckinfo, MMIO_CREATERIFF);
If you are creating a "RIFF" or "LIST" chunk, you must specify the form type or list type in the fccType member of the MMCKINFO structure. In the previous example, "RDIB" is the form type.
If you know the size of the data field in a new chunk, you can set the cksize member of the MMCKINFO structure when you create the chunk. This value will be written to the data size field in the new chunk. If this value is not correct when you call mmioAscend to mark the end of the chunk, it will be automatically rewritten to reflect the correct size of the data field.
After you create a chunk by using the mmioCreateChunk function, the file position is set to the data field of the chunk (8 bytes from the beginning of the chunk). If the chunk is a "RIFF" or "LIST" chunk, the file position is set to the location following the form type or list type (12 bytes from the beginning of the chunk).