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Tutorial: Grass Valley ADVC-G1 Converter

Some video switchers have built-in scan converters for converting VGA signals to an internal standard that you can use in your live production workflow. If you don't have that, then you're going to need a converter like the Grass Valley ADVC-G1 that can convert that VGA to your output. In this tutorial we'll explore how the ADVC-G1 works and how you can incorporate it into your workflow.

 

Grass Valley markets the ADVC-G1 converter as an any-source-to-3G SDI converter, but specifically they mean it's an HDMI input, DVI-I input, and analog video input converter. The "I" in DVI-I stands for integrated, and includes both analog and digital and both single- and dual-link DVI standards.

Digital and Analog Inputs

The DVI digital side isn't too terribly exciting. It's very similar to HDMI, but for me the exciting part is the A side, the analog side, because it can be converted from a VGA input using a very simple adapter, like the one shown in Figure 1 (below), which has DVI on one side and VGA on the other side. These are very inexpensive adapters of the sort that ship with video cards and what not--most likely, you already have a few sitting around your studio.

Figure 1. A typical VGA-to-DVI adapter.

It might sound a little bit strange to be describing VGA as "exciting" in 2014, but unfortunately, when it comes to IMAG and powering projectors, a lot of the presentation world still runs on the VGA standard for a variety of reasons. If you're doing live switching and incorporating computer inputs, you need to be prepared to work with the VGA standard and convert it to a digital standard that our video switchers can handle.

Some video switchers have built-in scan converters, which is what's required to convert VGA to an internal standard that you can work with. If you don't have that then you're going to need a converter like the Grass Valley ADVC-G1 (Figure 2, below) that can convert that VGA to your required output. In this case, that means SDI, but there are also converters that can do HDMI, and those are really the two digital standards that video switchers are built around.

Figure 2. The Grass Valley ADVC-G1. Click the image to see it at full size.

On the audio side you can work with the embedded HDMI audio as well as a 1/4" TRS analog input or AES or EBU digital audio inputs, which you can embed into the HD-SDI output.

Outputs

On the output side (see Figure 2), the ADVC-G1 supports two 3G HD-SDI outputs. The 3G HD-SDI standard simply means that it supports resolutions of up to 1920x1080 at 60 progressive frames per second (fps). The 1.5G standard does not support those progressive frames, maxing out at 60i.

Signal Processing Options

There are a few different signal processing options available. One of the more interesting options is 3D NR--3D noise reduction--which is really useful when you're working with compressed codecs, generally on playback from a non-live source. If your source camera is a small sensor-type camera--using a 1/3" or 1/2.8" sensor--or if you're working in high-gain or high-ISO environments, or even when you're upconverting from an analog source to digital or to a larger frame size, all of those scenarios can produce a little bit or a lot of noise when you're upconverting and processing. Using a bit of noise reduction really goes a long way, and it's especially important when you're webcasting, especially because you're using a very small bitrate and high compression ratio. Noise detracts from the detail in your video, so the higher signal-to-noise ratio, the better your finished video will look.

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Figure 3. The bottom panel of the ADC-G1 shows image-processing and enhancement options. Click the image to see it at full size.

The second image-processing feature is Image Enhance, which enhances detail by increasing the sharpness. You wouldn't want to use that feature if you were working with a noisy signal, but if you already have a very clean signal to begin with that's noise-free, you may want to add some sharpness to your image.