HD-SDI Vision Mixing
In recent years there has been considerable development in video formats which has resulted in high-quality, flexible systems. Most notably with advent of HD video.
This article has been written to give a basic overview of the main terms and concepts associated with this.
What has changed?
Only a decade ago most video was Standard Definition - less than half the resolution of modern High Definition. High Definition relates primarily to the resolution(number of pixels)displayed - more pixels generally means a clearer image. However there is more to it than than that, just having a lot of pixels does not mean the images is good. More important is how little noise there is and how broad the dynamic range of the image - these two factors are arguably more important than resolution, especially on smaller screen.
HD video tends to be transmitted in digital format, as opposed to analogue, which means a more accurate image reproduction and less noise and inteference.
What is Dynamic Range?
Dynamic range refers to the depth of tones and colours - it can be likened to how much range in contrast is available and how many steps there are within this range. High dynamic range is important as it gives a more realistic image with more drama.
SDI, HDMI and DVI?
These are three different main digital transmission systems. Here is a basic overview:
- SDI - "Serial Digital Interface" - this is a broadcast grade transmission system which is currently used for commercial video - you will not see it on the back of your TV any time soon. SDI allows for HD video over long distances and is the standard for top-tier production and broadcast companies.
- HDMI - "High Definition Multimedia Inteface" - this is a consumer-grade HD video and sound transmission system. It provides very good video and audio quality on a simple and cheap connector. However cable distances are limited to no more than 10m - as such it cannot be used as a primary transmission system for production purposes. You will see HDMI connectors on most modern consumer video equipment. We do use HDMI as an attachment method to screens and laptop but the signal is immediately converted to SDI.
- DVI - "Digital Visual Inteface" - generally speaking DVI is a connector that carries digital video. HDMI signals actually carry a DVI signal (but not always). DVI is common on the back of computers but seems to be getting replaced with HDMI these days.
What equipment do SXS have?
We hold a considerable stock of broadcast grade HD video equipment. Our primary transmission format is HD-SDI which is for professional applications only. This format allows for long cable runs and full HD video. We also hold BlackMagic Design broadcast vision mixers, Blackmagic SDI converters and Van Damme SDI (BNC) cabling.>
We are very proud of this equipment as it allows a level of video quality on par with HD broadcasters, which we feel that is the level of quality that guests and delegates are now expecting.