File Formats Explained
I've found that a number of my customers
seem to have a very fuzzy idea of what a
“file format” is and what it means regarding which applications know
how to deal with which ones.
What follows is a very brief discussion of the subject.
If the subject really interests you, I recommend visiting
Wikipedia as a jumping
off point.
In particular, look at the pages on
File format,
and perhaps
Binary Encoding.
A word of warning: this can quickly become the deep end of the pool,
so don't be surprised if you find yourself awash in unfamiliar
terms and concepts.
What are “file formats” and why should you care?
All information inside a computer is, ultimately,
just a string of ones and zeroes.
What those ones and zeroes stand for is a matter of opinion.
That opinion is called a “file format.”
Humorous aside: during an early Internet
flame war,
as people were literally screaming insults at each other
through their keyboards,
Gene Spafford famously said, "Calm down, it's only ones and zeroes."
There are "classes" of formats
which are fairly distinct from one another. Within each class,
most formats accomplish the same general purpose, but will
have some aspects that they handle better (or worse) than
other formats.
For example:
| Format Type | Examples |
|---|
| Audio |
.mp3, .aac, .wmf, .ale, ape, .wav, .flac, .ogg, etc.
|
| Streaming Audio |
.ram, .avi, .mp4, etc.
|
| Images |
.gif, .jpg, .png, .bmp, .tif, and many more
|
| Text (plain and formatted) |
.txt, .rtf, .doc, .otf, .swf, etc.
|
| Application Specific |
.psd (Photoshop), .doc (MS Word, WordPerfect),
.msi (MS program installer), the list is endless.
|
Differences Within a Class
Within the Audio class, WAV represents the raw,
uncompressed information on a music CD. FLAC (Free Lossless Audio
Codec) is a compressed version of a WAV file that decompresses
to be identical to the original (hence the word 'lossless' in its
name). MP3, AAC, etc., are "lossy" compression algorithms. When
decompressed, they provide an approximation of what the original
was. Some lossy formats focus on smaller file size (with a
drop in perceived audio quality), while others focus on quality
(with a concomitant increase in size). Not even all MP3s are the
same. Old MP3s were 'low bit rate' and sounded horrible even on
low-end speakers, newer VBR MP3s (variable bit rate) are quite
good, but they are also about 30% larger than the older ones.
(More to come...)
|
