Tech Magazine

Multimedia File Extensions

Posted on the 06 September 2011 by Nerdywerds @NerdyWerds
Audio and Video are everywhere, and they all seem to have different encoding schemes

If you've owned or used a computer for any significant length of time, you've probably worked with it's file system. A file system is the way your computer organizes files and data on your computer. You may have also noticed that the files had a certain format;, where xxx is the file's extension. A file extension tells the computer what type of encoding method is used by that file. Disk drives can not store data in the same way you and I can. It must use the ever famous 0s and 1s binary system. So the data must be encoded in such a way that it can be retrieved, decoded and displayed in a manner we can understand. There are many encoding formats out there, and for this reason, we need file extensions. If you see a .doc file, you're computer knows it is encoded using Microsoft's Word format, a .txt file is a plain text document.

For the sake of our collective sanity, and simplicity, we'll only be discussing media extensions today. In particular, we're going to go over image, audio and video encoding methods.

We will first talk about image file formats. As we discussed earlier, your disk drive sees files as 0s and 1s. You could imagine how difficult it can be the store a picture as 0s and 1s. That is where these common image formats come into play. In order to accomplish adequate compression, many formats utilize "lossy compression". Lossy Compression is a method of encoding data that compresses data by discarding some of it. If you've ever looked at highly compressed image files, you'll be able to notice quality degradation and pixelation(appearance of noticeable squares of color). There are some image formats that use lossless compression(compression without any lost data). Refer to the table below for information about which encoding methods use what level of "lossyness".

Format Lossy/Lossless Description

JPEG/JPG Lossy JPEG files average 10:1 compression ratio, with little quality degradation

GIF Lossless GIF's are limited to 256 colors and can also be animated

BMP Lossless BMP's tend to be large files due to a lack of compression or very low ratio compression

PNG Lossless PNG was designed be be an improvement and replacement to GIF's

TIFF Can use either TIFF is a very versatile format, with the ability to hold lossy and lossless images.

SVG Neither SVG is an xml(text) based encoding method. The image is composed of scalable images, instead of dots.

Digital media is everywhere. Whether it be music (mp3, wav, vorbis) or video (mpeg, mov, avi), media is inescapable today. The format of a video or audio file isn't really necessary knowledge, but it is nice to know. Audio/video files enjoy a level of complexity far beyond that of image files. There is a great deal more data to contend with, and the methods of playback, streaming as opposed to a static display, make these files very intricate and difficult to understand. We are just going to touch on some basics here, what they are, whether they are audio or video and some general information about them.

Format Audio/Video Description

MP3 Audio The most common method of encoding audio data. It utilizes lossy compression.

AAC Audio AAC is a standard encoding scheme designed to succeed MP3.

WAV Audio WAV files are generally uncompressed, therefore larger files. It is a Microsoft and IBM format.

Vorbis Audio Vorbis is an open source, relatively new, audio encoding format. Often used with the Ogg container format, so you may see "Ogg Vorbis" on occasion

MPEG Video MPEG is a very popular video encoding format. It features highly complex encoders and surprising simple decoders.

MOV Video MOV files are used by the QuickTime player. Data is stored in tracks, audio, video, effects or text.

AVI Video AVi is a video format introduced by Microsoft in 1992. AVI files contain audio and video data for synchronous playback.

Back to Featured Articles on Logo Paperblog