HD Webcast Production: Choosing Video Scalers and Converters
Streaming Media by Shawn Lam
In this ongoing Streaming Media Producer series on webcast video production, Shawn Lam covers the video format converters he uses in his own HD webcast workflows, and one new converter that just might be the video converter, scaler, and distribution amplifier to rule them all.
My life would be so easy if every camera and laptop that I need to connect to my video switcher had multiple live outputs and could support the 1920x1080 30P resolution and frame rate that I prefer to use--and included in these multiple outputs is the professional connection standard of 3G HD-SDI. But this isn’t the case and will never be; laptops don’t offer HD-SDI outputs. So in order to connect the variety of input devices that are common in the webcasts that I produce, I rely on a variety of video format converters, scalers, and distribution amplifiers (DA). For simplicity I am going to assume that the video switcher you are using is a digital video switcher primarily designed for HDMI and/or HD-SDI video inputs, and not an HD analog video switcher, or either a digital or analog SD video switcher.
The need for converters, scalers, or DAs depends largely on the type, number, and resolution of the video outputs from the devices (camera and computer) that you are trying to connect and the devices that you are connecting to. The most basic setup would be a single camera connecting to your webcast encoder using an HD-SDI cable but the moment you add either an additional camera angle or computer input, you need to add a video switcher and possibly one or several converters, scalers, or DAs.
Simple Video Format Converters
Some video switchers have internal video format scan converters, and hence can accept a wider variety of inputs. Increasing available video inputs from HDMI or HD-SDI to include VGA solves the most common connection challenge that webcasters are faced with. Unfortunately, A/V companies still default to using VGA cables to connect laptops to projectors and laptops to presentation video switchers that connect to projectors.
One reason is that VGA cables (and the equivalent 3- or 5-wire group of composite cables with BNC connectors--see Figure 1 below) can run longer than digital DVI or HDMI cables; the other is because these companies are primarily catering to their clients’ needs for displaying computer inputs on projection screens, and adding a webcast output is an afterthought, which means it’s the problem of the video production company doing the webcasting. read more...
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|Roland VC-1-SC Up/Down/Cross Scan Converter $995.00||Grass Valley ADVC G-1 Any In to SDI Converter $999.00||Matrox Convert DVI Plus HD-SDI Scan Converter with Genlock $995.00|
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