Early history of multimedia support in personal computing operat

In the first half of 1990s, Microsoft called its multimedia support Video for Windows (VFW). Although we might be exaggerating if we said that this support was a well-defined, robust, layered architecture, it was definitely a start in the right direction of supporting data that consisted of more than text and numbers. Microsoft's VFW offering coincided with Apple's offering multimedia support that it called QuickTime (QT). QT and VFW came on floppy disks or CD-ROM discs with their respective operating systems, although users often needed to install them separately. At the time, you did not expect to download updates from a network. A typical game diskette or CD-ROM included a particular version of QT or VFW that you installed as part of the game, even if a later version already existed on your system. In general, a game would run only if it was the last multimedia application that you had installed. Preparing a demonstration of more than a couple of games on one computer was a practical impossibility.

At this time, Microsoft was involved with IBM and others such as Intel in defining the formats and functions for multimedia architectures and operating systems support. One result was the audio-video interleave (AVI) file format for video with audio. Interleaving audio and video ensured some synchronization between them. The AVI file format included a specification for a header that told what video and audio compression codecs a file used, often including codecs from multiple vendors. AVI became an important part of VFW, along with a corresponding video capture program (VidCap) and a simple editor (VidEdit). Another result of the collaboration was the media control interface (MCI) that passed the hardware commands such as start, read a track, and rewind. Intel made some of the key hardware, such as the Intel Smart Video Recorder adapter card.

As the 1990s rolled on and more developers became serious about creating multimedia, serious limitations became increasing evident in the multimedia operating system support. VFW failed to support several important codecs, such as MPEG-1 and QT. It had no blue-screen support. Despite interleaving, it had no system-level synchronization among various media components. During playback, it tended to drop or repeat video frames and segments of audio, which caused unacceptable stuttering. It had poor throughput because it limited internal transfers to a maximum of 64 KB at a time, in each buffer, which required a processor to interrupt what it was doing and copy a buffer 2 to 3 times each second. Its file limit of 1 GB became highly restrictive as years went by.

Go To Page: 1 2

Articles in this Topic    Discussions in this Topic