Hello trid users,
some days i run ccleaner cleanup tool on Windows. One option is called "Unused
File Extension". When i use this option it complains about file name suffix
AFF. So i looked on my systems for such files. Unfortunately this suffix is
used by different file types. In this session i will only consider audio
related samples.
So i run trid utility on my AFF audio examples and related files. All samples
are described with low priority as "Generic IFF container" by iff-gen.trid.xml
without mime type. All samples are described as "AIFF Audio Interchange File
Format" by audio-aiff.trid.xml with mime type audio/aiff. Here 2 file name
extensions (AIF/AIFF) are listed (see appended output/trid-v-old.txt)
For comparison reason i also run the file format identification utility DROID
( See
https://sourceforge.net/projects/droid/). Here all examples are
recognized. The samples are described as "Audio Interchange File Format" by
PUID fmt/414. No mime type is listed here. Here also 2 file name extensions
(AIF/AIFF) are considered as valid. The suffix AFF is here considered as
invalid (See EXTENSION_MISMATCH true in appended output/droid-aiff.csv).
For comparison reason i also run file command (version 5.44) on such
samples. Here the samples are described as "IFF data" with sub classification
as "AIFF audio" (see appended output/file-5.44.txt). But here another mime
type audio/x-aiff is listed (see appended output/file-i-5.44.txt). No file
name extensions are listed here (see appended output/file-ext-5.44.txt).
In generic iff-gen.trid.xml a page about Interchange File Format on Wikipedia
is listed. There the mime media type application/x-iff is listed. That type
is also shown on Linux systems by the shared mime database. So i add this in
definition by line like:
<Mime>application/x-iff</Mime>
In audio-aiff.trid.xml a page on apple.com web server is used as
reference. Unfortunately that link is dead. So i choose page about AIFF on
file formats archive team web server. So this is now expressed by line like:
<RefURL>
http://fileformats.archiveteam.org/wiki/AIFF</RefURL>
There 2 mime types are listed. In current definition the mime type audio/aiff
was used, but when i look at IANA there is such type not officially
registered. On Linux machines by shared mime database the other type is
used. This is also shown by file command (see appended
output/file-i-5.44.txt). So i now also use the other type. This is expressed
by line like:
<Mime>audio/x-aiff</Mime>
In current deviations 2 file name extensions (AIF/AIFF) are listed. On the new
reference site also a third suffix AFF is listed. On the site you can also
download such samples. It is not explained why but i assume that are for
historical reasons. The file format apparently starts on Amiga systems and on
Apple Macintosh computer systems. There the 4 byte suffix aiff could be used.
Because of limitations of old FAT file systems on DOS only 3 byte suffix can
be used. So in most cases here the suffix shrinks now to AIF. Apparently on
such file systems also the other 3 byte variant AFF is also used. So now all 3
possible file name suffix are expressed by line like:
<Ext>AIF/AIFF/AFF</Ext>
With the updated trid definitions now all my audio samples are described. TrID
definitions and output are stored in archive aff_aiff_.zip. I hope that my
definitions can be used in future version of triddefs.d
With best wishes
Jörg Jenderek
