Image formats – Various image formats are
Graphics Interchange Format ( GIF ) – Images in this format are used for banners, clip art, and buttons as they can have a transparent background where in parts of the image, the background will be allowed to show through. They are not compressed, which results in slow load times and large transfer rates. Gifs are limited to the 256 color scheme. They create a simple animation called as animated GIFs.
Joint Photographic Experts Group (JPEG) – Images in JPEG format have an unlimited color palette, and have a high compression rate thus reducing load times and disk space. They are a standard for storing and compressing images such as photographs that use a wide range of colors.
Portable Network Graphics (PNG) – It is an extensible file format for the lossless, portable, well-compressed storage of raster images. PNG provides a patent-free replacement for GIF and can also replace many common uses of TIFF. Indexed-color, grayscale, and true color images are supported, plus an optional alpha channel. Sample depths range from 1 to 16 bits. PNG also compresses better than GIF in almost every case (5% to 25% in typical cases).
Audio formats – The most used audio file formats are
MP3: MP3 is a popular format for music due to good compression and good audio quality. Files have an .mp3 file extension and usually play in most browsers. The MIME type is audio/mpeg.
WAVE: It was developed by IBM and Microsoft, and is supported by most web browsers. Files have the .wav file extension. It does not use compression, so its quality is better than MP3 but for which good-quality speakers are needed. Due to uncompressed format its file sizes is very large. Its MIME type is audio/x-wav.
MID It stores a score in music which tells about how to play a piece of music, and not the audio. It specifies different parts to be played on different instruments. It is used to play music but now mp3 is more widely used.
Other audio formats popular on internet but needing their own plug-ins are
- Windows Media Audio – It requires the Windows Media plug-in
- QuickTime – It requires the QuickTime plug-in
- Real Audio – It requires the Real Media plug-in
MP3 format is preferred as it compresses to relatively small file sizes while retaining a good sound quality thus widely supported.
But for high quality audio WAVE format is used and for Digital Rights Management (DRM) Windows Media Audio or Real Audio format is used
Video Formats – The most used file formats are
FLV or Flash video – It is the most popular format due to flash player plug-in is installed on most computers. Creating video needs the flash authoring software which can also create video players for playback thus facilitating in control of look and feel of the player. It uses flv or swf file extension and it has good compression and thus lower files size.
MPEG It is a video format developed by the Motion Picture Experts Group (MPEG). Most computers have a windows media player or quicktime player which plays MPEG video format files. It has mpg file extension and its file size is larger than flash.
WMV or Windows Media Video It requires windows media player to play it and has wmv file extension.
MOV files are based on quicktime movie file format which can have file extension of MP4 or mov and has small file size.
AVI (audio/video interleaved) It is known as a container format as in it video is compressed with another codec thus some AVI files may play, and not others. Its file extension is avi.
RealVideo It was the first video formats used for showing video online. Its file extension is rm.
Flash Video is the most popular video on the web.
