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Inside Macintosh: Sound /
Chapter 2 - Sound Manager / Sound Manager Reference
Data Structures


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Important: Inside Macintosh: Sound is deprecated as of Mac OS X v10.5. For new audio development in Mac OS X, use Core Audio. See the Audio page in the ADC Reference Library.

Form Chunks

All sound files begin with a Form Chunk. This chunk defines the type and size of the file and can be thought of as enclosing the remaining chunks in the sound file. The ContainerChunk data type defines a Form Chunk.

TYPE ContainerChunk =
RECORD
   ckID:       ID;         {'FORM'}
   ckSize:     LongInt;    {number of bytes of data}
   formType:   ID;         {type of file}
END;
Field Description
ckID
The ID of this chunk. For a Form Chunk, this ID is 'FORM'.
ckSize
The size of the data portion of this chunk. Note that the data portion of a Form Chunk is divided into two parts, formType and the remaining chunks of the sound file.
formType
The type of audio file. For AIFF files, formType is 'AIFF'. For AIFF-C files, formType is 'AIFC'.
The size of an entire sound file is ckSize+8, because the ckSize field incorporates the size of all chunks of the sound file, except the sizes of the ckID and ckSize fields of the Form Chunk itself.


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© Apple Computer, Inc.
2 JUL 1996