In earlier chapters, you might have learned about how operating systems handle general data, like text files, programs, binary files, word-processing documents and also spreadsheets. Moreover, operating systems may get the task to handle different kinds of data as well which comes in the category of multimedia. A recent trend in technology is the inclusion of multimedia data within computer systems. Multimedia kind of data consists of continuous media in the form of files (audio or video) data as well as conventional files to run. Continuous media data vary from conventional data like that where continuous media files — such as frames of video or images or audio files — must be delivered according to certain time restrictions.
What is Multimedia?
The word multimedia depicts a large range of applications which are in popular use now-a-days. This term covers a large category that includes audio and video files like MP3 audio files, movies, short video clips and flash / animation files of movie previews or news stories that are being downloaded via the Internet.
Multimedia concept also includes live webcasting (i.e. broadcasting over the World Wide Web) of various events or sports. Multimedia applications should not have to be either audio or video; instead, a multimedia application can include a mixture of both.
What is Media Delivery?
Multimedia data gets stored in the file system just as any other data. The main dissimilarity between a regular file and multimedia file is that the multimedia files have to be accessed at an exact rate but accessing a regular file requires no particular timing. The video is usually represented by a sequence of images which is known as frames which are used to display in rapid succession. The faster the frames are displayed to users the smoother the video looks. Mostly, a rate of 24 to 30 frames per second has to be necessary for the video for appearing smooth to human eyes.
When any data gets delivered from the local file system, you can refer to that delivery as 'local playback'. Multimedia files can also be stored on a remote server and delivered to a client across a network with a technique called streaming.
There are two types of streaming techniques:
- progressive download and
- real-time streaming
With a progressive download, any media file having both audio and video can be downloaded and stored on the users' local file system. Real-time streaming varies from progressive download wherein the media file gets streamed to the client but can be only played—and not stored/downloaded — by the client.
As the media file does not get stored on the client system, real-time streaming is much preferred to progressive download for media files which might be too large to store on system, like long videos and Internet radio or TV broadcasts.
Characteristics of Multimedia Systems
The demands of multimedia systems are nothing like the demands of conventional applications. Mostly, multimedia systems may have the below-mentioned characteristics:
- Multimedia files can be relatively large. Let's take an example; a 100-minute MPEG-1 video file uses roughly 1.125 GB of storage, 100 minutes of high-definition television needs roughly 15 GB of storage.
- Continuous media might need very high data rates. Think of a digital video, wherein a frame of color video is displayed at a resolution having 800 x 600.
- Multimedia applications are quite sensitive to time delays at some point in playback.