Files of this type and auxiliary type contain sampled sound data.
Files of type $D8 should contain sampled or digitized sound data. The data is intended to be fed to sound hardware to reproduce a sound that was recorded "live." The converse to "sampled" sound is "synthesized" sound, where a computer creates wave forms and feeds them to sound hardware.
Sampled sound data can be stored in many formats. The data is traditionally sampled in discrete intervals, with a given number of bits used to record the intensity of the sound at the sampling point. In addition to the samples themselves, this requires that the file contain the sampling interval (or rate) and perhaps the number of bits used in sampling. Other information may be needed by applications, such as the duration of the sound, comment or copyright information, compression information or parameters, or "markers" which denote specific points within the sampled sound.
Apple Computer, Inc. presents a standard for such files, the Audio Interchange File Format (Audio IFF), described in another File Type Note. While Audio IFF is suitable for many needs, it cannot hope to cover all. Apple assigns auxiliary types in this file type for such purposes.
Note: Apple does not recognize a standard in which the sampling rate is contained in a file's auxiliary type. Doing so is not possible within the realm of file type and auxiliary type assignment.
The following auxiliary type assignments are current for this file type as of the publication date of this Note:
Auxiliary Type Short Name Developer _________________________________________________________________ $0000 Audio IFF Apple $0002 ASIF instrument Apple $0003 Sampled Sound Resource Apple $8001 HyperStudio sound Roger Wagner Publishing _________________________________________________________________ Table 1 - Auxiliary Type Assignments
The auxiliary types for this file type are reserved; any not listed in this Note or About File Type Notes must be assigned by Apple Computer, Inc. Using any file type or auxiliary type not assigned may result in conflicting identification of files by totally unrelated programs. To obtain an auxiliary type assignment in this file type, see About File Type Notes.
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