It is becoming more common to find video integrated into today's computer environment. Video conferencing, synthesized imagery, live video, animation/video, and other motion imagery have created a need to bring video to the desktop.
Part of the challenge of video-on-the-desktop is the need to compress video images. Working with uncompressed video images is not practical because of the demands that the uncompressed images make on processors, storage, and networks. As an example, it takes more than 900 Kbytes to store a single frame of an uncompressed 24-bit RGB 640x480 pixel image.
The other part of the challenge is fast compression and decompression speeds. The need to compress and decompress video images in real time is a requirement for video conferencing applications. The SunVideo subsystem meets this requirement with its on-board video compression engine that supports multiple compression standards.
The SunVideo subsystem is a real-time video capture and compression
subsystem for Sun
The SunVideo subsystem is an essential component for implementing video conferencing and multimedia applications.
The SunVideo card is a digital video card - it buffers digital video in its data buffer so that the digital data can be downloaded to and processed by the host CPU at rates of up to 30 frames per second (fps).
The SunVideo subsystem is designed to work closely with applications that use the facilities of the XIL Imaging Library platform. By itself, XIL provides functions for image processing and software-based image compression and decompression. When used in conjunction with the SunVideo subsystem, XIL programs take advantage of the SunVideo card's ability to capture and compress video images. XIL also provides a deferred execution facility that accelerates execution of commonly used operations.
The SunVideo card's single-chip compression engine supports the following compression techniques, which are discussed in Appendix B, "Video Compression."
Table 1-1 summarizes the performance capabilities of the SunVideo subsystem.
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Compression Method Frame Rate (Frames Per Second) NTSC (320x240) PAL (384x288) -------------------------------------------------------------------------------------------
CellB 30 25
JPEG 301 25
MPEG-1 (variable bit 301 25
rate)
MPEG-1 (constant bit 18 17
rate)
UYVY 301 25
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The SunVideo subsystem is a video capture and compression device; it does not decompress video data. Applications use XIL's software-based decompression functions to decompress video on the host, and a SunVideo subsystem is not required to decompress video. Therefore, decompression frame rates are a function of the host CPU's performance.
The SunVideo subsystem does not provide direct support for audio. Applications requiring audio, such as video conferencing, can use /dev/audio or telephone services for audio support.
Some examples of the applications in which the SunVideo subsystem can be used include:
For video conferencing, applications at two locations use SunVideo cards to capture and compress video images. The applications send and receive the compressed bitstreams and decompress the images in real time. The applications would also synchronize the video and audio bitstreams.
An important part of the SunVideo subsystem's ability to support video conferencing applications is the CellB video compression technology. CellB compression, a non-proprietary technology developed and published by Sun Microsystems, provides high quality, low bit-rate image compression at low computational cost.
Appendix B, "Video Compression," provides an overview of the compression technologies that the SunVideo subsystem supports.
For multimedia authoring, an application can use a SunVideo subsystem to capture video sequences - from live video or from recorded video. Depending on the requirements of an application, a user can select from the different compression techniques that the SunVideo subsystem supports. The compressed video can be stored in a file so that it can be edited and integrated into a multimedia presentation. Other parts of a multimedia authoring application could take advantage of the image processing functions of XIL to manipulate the captured images.
Depending upon business needs, compressed video images can be integrated into corporate databases to present information more effectively. Here are some examples:
Compressed video clips can be inserted into your online documents. The capture and insertion of compressed video into documents gives publishers an array of options for creativity. For example, a newspaper publisher on the east coast could share compressed video clips with subsidiaries by transmitting the compressed images via a satellite connection.
Along with the SunVideo card, you can use the Sun Tuner to display broadcast or CATV programs in a window on your workstation. The Sun Tuner has no external controls. Instead, you use the Sun Tuner software to select among 125 channels, mute and unmute audio, fine-tune channel frequencies, and scan for available channels.
The Sun Tuner from Sun's Advanced Products Group is available through SunExpress.
