Serial Digital Interface, better known in the AV world as SDI is a digital interface first standardized by SMPTE (The Society of Motion Picture and Television Engineers). The SDI standard allows transmission of uncompressed and unencrypted digital video signals in broadcast-grade video, studio, live staging and post production applications. Serial Digital Interface use coaxial cables with BNC connectors and are produced in a few different standards including SD-SDI, ED-SDI, HD-SDI, Dual Link HD-SDI and 3G-SDI.
Since we are talking about SDI Switchers, let’s go over the different classifications they come in. The most basic SDI switcher for example is a 4 SDI input and 1 SDI output. The next category is a fixed I/O SDI matrix switcher. Fixed SDI matrix switchers are usually made in a chassis that has a 4x4, 8x8, 16x16 and 32x32 I/O’s. In some cases, the user would like a customized chassis with a certain amount of I/O’s. In this type of scenario a modular SDI matrix switcher would be the best solution.
A modular SDI matrix switcher allows the user to customize the chassis with how many inputs and outputs is needed for the application. This type of switcher provides flexibility to start with a few I/O’s and add more if desired. Lastly, a seamless SDI matrix switcher with PIP (picture in picture) feature. These units are more advanced and perform at a high level to provide the best resolutions with true seamless switching. True seamless switchers allow the user to select transition effects when switching which adds professional appeal to any application. When working with switchers, it’s important to understand reclocking and what it is. Reclocking is synonymous to “refreshing” a signal. When a clock signal is run over a long cable the signal may likely suffer. Degradation can take the form of noise and decrease in amplitude.
High performing SDI switchers are equipped with reclocking technology to help manage the quality of a signal coming in. Another feature found in many SDI switchers is embedded audio. Embedded audio has many benefits including taking the same route as the video signal and making them sync. Also, the video routing switcher routes the audio and additional levels are not required. This also allows video and it’s audio to be patched with one patch cord. The downsides include no audio breakaway, audio can’t be adjusted once embedded and in some cases embedded audio may not pass through some devices.
Manufacturers have been very technical when developing and designing high quality SDI Switchers. Control is simplified by using the front panel buttons, IP, IR remote or RS-232 for SDI switchers. We are partnered with industry leading manufacturers including Atlona, Gefen, Kramer Electronics, Avenview, Shinybow, TVOne and Hall Research. One of our tech savvy representatives can answer any questions you may have regarding SDI switchers and your project.