@database AIFF.guide
@author "Olaf `Olsen' Barthel"
@$VER: AIFF.guide 1.1 (25.11.94)
@node Main "AIFF sound datatype"
                   AIFF Sound DataType for Workbench 3.0
                      Written by Olaf `Olsen' Barthel
                               Public Domain
                            I.   @{" Introduction " link Introduction}
                            II.  @{" Installation " link Installation}
                            III. @{" Features     " link Features}
                            IV.  @{" Bugs         " link Bugs}
                            V.   @{" Author       " link Author}
                            VI.  @{" History      " link History}
@endnode
@node Introduction
"AIFF" is an acronym for "Audio Interchange File Format". This file format
was devised by Apple Computer, Inc. and a number of third party developers
and is mostly used on Apple Computers, such as the notorious Apple II,
Apple IIGS and the Apple Macintosh. With the introduction of System 7 the
Sound Manager was enhanced to support direct playback of "AIFF" and "AIFC"
format files, thus making this file format an integral part of the
Macintosh operating system. Most digital sound recording software on the
Apple Macintosh supports "AIFF" as the native sound file format. Recently,
"AIFF" was adopted for use with Kodak Portfolio CDs since the corresponding
development software is largely Macintosh-based.
"AIFF" and its `sister format' "AIFC" are in many ways similar to the
"8SVX" IFF format which is commonly used on the Amiga. Both are stored in
IFF format, can contain sampled sound data and offer means to store musical
instrument data. Unlike "8SVX" it provides additional services, such as MIDI
support, data markers and audio recording information. Sampled sound data
is stored interleaved for multiple channels, making it easy to replay
stereo sound. Samples do not need to be eight bits wide, such as required
by the "8SVX" format. In fact, they can be anything from 1-32 bits wide.
While both "AIFF" and "AIFC" share the IFF file structure and thus are
designed as interchangeable file formats to be used on many computer
platforms Apple Computer, Inc. added data compression support to "AIFC". As
always, all the standard data compression methods are based upon
proprietary algorithms to which Apple Computer, Inc. probably holds patents
and is unwilling to share. In essence, this restricts the portability of
compressed "AIFC" files.
@endnode
@node Installation
The "AIFF" datatype distribution should consist of the following files:
 aiff.datatype
 AIFF
 AIFF.info
 AIFF.guide
 AIFF.guide.info
 Source code, in archived form
Copy the file "aiff.datatype" into the "SYS:Classes/DataTypes" drawer. The
"AIFF" and "AIFF.info" files should be placed in the "DEVS:DataTypes"
drawer. In order to use the datatype you will need to reboot the machine.
@endnode
@node Features
The "AIFF" datatype can read and process both "AIFF" and "AIFC" format
files which include sampled sound data. In the case of "AIFC" files the
sound data needs to be stored in uncompressed format.
Sound samples will be cropped to eight bits per sample, stereo and
multichannel data will be added up to yield monophonic sound.
In order to compensate for memory shortages or sound replay rates the Amiga
sound hardware would be unable to support the quality of the sound may get
scaled down.
In order to make the sound use the full dynamic amplitude range the sound
data is normalized after loading.
@endnode
@node Bugs
When running under Workbench 3.0, sounds larger than approximately 102400
bytes will not play correctly. This is actually not a fault of the
macsnd.datatype, but rather of the sound.datatype superclass which does no
double-buffering. Application software can, however, easily compensate for
this limitation.
@endnode
@node Author
The "AIFF" datatype was written by Olaf `Olsen' Barthel using SAS/C 6.51.
In order to recompile it you will need the Includes Release 40.15 or
later. The datatype, the documentation and the accompanying source code are
placed in the public domain.
The author can be reached at:
   Olaf Barthel
   Brabeckstra
   D-30559 Hannover
   Federal Republic of Germany
or via Internet:
   olsen@sourcery.han.de
@endnode
@node History
v1.11
The sound reader could trash 1-3 bytes following the allocated sample
data, this has been fixed. The reader now uses Martin Taillefer's
asyncio routines which I modified slightly for reentrancy. I also
added a new routine which this datatype does not yet need.
v1.10
Small changes to the sound normalization code.
This release no longer requires v40, but you may still experience problems when
running under v39. See the section entitled @{"Bugs" link Bugs} for more information. There is
no longer so much stack space required to use this datatype. If necessary it
will allocate new stack memory for itself and use it. Older releases could
slightly distort the sound while normalizing it, this has been fixed.
@endnode