How to choose the converter from VGA signal to video signal

With the development of computer hardware technology and increasingly rich software functions, an ordinary computer can now produce program effects that exceed those produced by expensive professional video equipment such as so-called professional graphics workstations and special effects animation workstations. But why are ordinary computers not widely used in TV production? The key is that the video programs produced by ordinary computers with good performance can only be viewed on the computer monitor, on the local computer or on the Internet, while computer equipment without professional video has corresponding video interfaces. This is a great pity for people who are still in the TV era.

In fact, as long as you choose a suitable computer VGA signal to video signal converter, you can greatly expand the equipment resources of TV program producers and give full play to their artistic creativity. So, how do you choose a VGA signal to video signal converter that meets the requirements of TV program production?

There are two important technical differences between computer monitors and TV monitors. The first is the scan rate. A computer scans an image on a monitor at a rate of 24,000 to 65,000 times per second (or 24 to 65 kHz) horizontally and 75 times per second (75 Hz) or more vertically. In contrast, a TV scans more slowly, about 15,000 times per second horizontally and about 60 times per second vertically. The function of a scan converter is to convert the fast scan rate of a computer image into the slow scan rate of TV technology. The second is the format in which a computer monitor and TV receive video signals. When a computer sends an image to a monitor, the video signal is broken down into separate red, green, blue, and sync blocks. A TV monitor receives a separate composite video signal. The scan converter needs to encode the computer's multiple video signals into a video signal that the TV can receive. Therefore, to convert a computer VGA signal into a video signal, scan rate conversion and encoding are required.

All computer VGA to video converters, regardless of price, follow the same process when converting images. But the differences are not just in functionality, but in the circuitry that implements the basic scan conversion function. Low-end, mid-range, and high-end products vary greatly in how they process images.

Low-end products are sometimes "software driven," which can cause conflicts with computer image processing or other applications. Also, low-end products have poor flicker filters, if any at all. Typically, low-end scan converters have lower resolutions, offering only 640x480, with some newer models offering 800x600. Low-end products may be able to accept a computer signal with 6.8 million colors, but the converted image will not have the same depth of color. Mid-range converters offer non-software performance and improved flicker removal, and can offer higher resolutions (typically up to 1024x768). They also offer 24-bit color processing, meaning that the converted image will have the same depth as the original.

High-end products have higher processing power and resolution up to 1600×1280, so more memory is needed. These models usually use advanced flicker elimination algorithms and are more flexible when accepting non-standard computer signals. High-end products usually have optional SDI output and HD SDI output, because when the computer VGA output resolution reaches 1600×1280, what we actually see on the computer monitor is HD image. So today, when high-definition television technology has begun to be applied, computer VGA signal to video signal converter is still a good tool for program production.

The product we chose in actual work is XTD 825D1 from Ananlog Way, France. It can accept input resolution up to 1280×1024 and sweep frequency up to 85Hz. It has external synchronous phase lock function. It can adjust black level and RGB gain according to different input resolution and displayed pictures. It has 7 levels of flicker suppression function. In actual use, we adjust various parameters to achieve the best effect of the converted picture.

We use this device in different occasions. For example, in the studio, we use this converter to input the screen of the scoring software in the variety show into the digital switcher, and send the analog composite signal to the large screen display on the scene. The production director can easily switch the on-site scoring situation directly to the TV audience through the switcher. In this real-time broadcast, the TV audience can clearly see the same picture as the on-site audience. This effect is much better than the traditional use of cameras to capture the image of the on-site screen. In the process of producing related financial, stock and other columns, a large number of charts, graphic information need to be displayed. By adjusting the relevant indicators of the VGA to video converter, we can clearly reproduce the images that we are usually used to seeing on computer monitors on TV.

At the same time, because VGA to video converter is an independent conversion device, it does not require any software installation, has no special requirements for the computer, and is easy to use, so it has a wide range of uses. In some live production programs, a portable computer, plus a live switcher, can easily add subtitles using VGA to video converter with Powerpoint software.

With such abundant Internet resources today, program production is no longer limited to professional organizations such as TV stations. Highly enjoyable visual works on the Internet can be fully displayed on TV, such as cartoons, animated MTVs, and game shows on the Internet. Moreover, the effect of conversion to TV can meet current and future high-definition production standards.