教程:草谷ADVC-G1转换器

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输入, 以及模拟视频输入转换器. DVI-I中的“I”代表集成, and includes both analog and digital and both single- and dual-link DVI standards.

数字和模拟输入

The DVI digital side isn't too terribly exciting. 它与HDMI非常相似, but for me the exciting part is the A side, 模拟端, because it can be converted from a VGA input using a very simple adapter, 如图1所示(下面), 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.

图1. 典型的VGA-to-DVI适配器.

It might sound a little bit strange to be describing VGA as "exciting" in 2014, 但不幸的是, 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. 如果你没有这个 then you're going to need a converter like the 草谷ADVC-G1 (下面的图2) that can convert that VGA to your required output. 在这种情况下, 这意味着SDI, but there are also converters that can do HDMI, and those are really the two digital standards that video switchers are built around.

图2. 草谷ADVC-G1. 单击图像以查看其全尺寸.

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, 可以嵌入到HD-SDI输出中吗.

输出

在输出端(参见 图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). 1.5G standard does not support those progressive frames, maxing out at 60i.

信号处理选项

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, 所以信噪比更高, 你完成的视频看起来就越好.

图3. The bottom panel of the ADC-G1 shows image-processing and enhancement options. 单击图像以查看其全尺寸.

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.