Video (Price versus Quality)
Learn the real difference in mobile video
By Paul Sonoda
More expensive stuff looks better. There I said it. If you sell to the high rollers, (read pharmaceutical transfer technicians) that’s all you need to know. For soccer mom’s, it’s all about price. Why do they care what the display looks like, it’s only there to keep their kids from asking…Are we there yet? Well it’s destination mobile video and we have arrived!
Mobile video is the fastest growing market segment in car audio. It’s no surprise to anyone. DVD is the fasted and most successful format launch in the history of recorded entertainment. It was only a matter of time before mobile video became mainstream. Today mobile video is available as in-dash, head rest, overhead and even in the bag display screens with DVD players. Choosing mobile video starts with determining where you want to have monitors and what type of video source (DVD, satellite TV, Playstation, etc,) is available in the car. Once that is determined, the next step is to select the right type and performance level of video for your taste and pocket book. If you want to get the right video system for you, the best place to start is to learn about the technology of displays.
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topHow LCD Panels Work
LCD stands for Liquid Crystal Display. Most common in mobile video, these types of displays originated in the computer industry. Common terms you will here are “Active Matrix” and “TFT” displays. In reality, they are both the same. “TFT stands for Thin Film Resistor. On an LCD panel, there is an array of thin film resistors. Send electrical current to any one of the resistors and the transistor allows light to pass through the panel. The point where the light passes through is called a pixel. It is also the smallest amount of light that can make up the digital image on the screen. Why this is important is the display resolution is largely responsible for the resolution or picture quality or your video display.
Media Demands
Currently there are several different media formats with ever increasing demand for pixel resolution. Standard terrestrial TV requires 460 x 480 pixels for 4:3 and 460 x 360 for 16:9 format. DVD demands even higher resolution at 720 x 480. In the near term future, HDTV will be available in your vehicle at a gigantic resolution of 1920 x 1080. In other words, a bunch of pixels.
Manufacturers Play the Pixel Game
Today, most mobile video screens come in 16:9 format. (Movie shape) And most companies sell their display based on the number of pixels. For example, a typical seven inch monitor displays are reported by their manufacturer as having 336,960 pixels. Wow! That sure sounds like a lot. But wait, the actual pixel resolution is 480 x 234. The high pixel count come from counting the red, green and blue pixels individually. LCD panel displays need three colored pixels to make one pixel resolution that comes from a DVD or other video source. Basically, it takes three pixels from a LCD panel to equal a single pixel from a DVD. Most companies will give you both the display resolution (comparable to media pixels) as well as the total actual pixels (marketing number).
Obviously, the higher the display resolution of a monitor, the better the picture quality you can expect. Most displays I discovered to have an average vertical resolution of 234 pixels with horizontal resolution from 480 to 1440 for standard seven inch monitor. That is less than half the vertical resolution of what you would need to fully display DVD. However, it should be noted that at seven inches, losing vertical resolution might be difficult to detect. Through my informal search, I found that Alpine , http://www/alpineusa.com had the highest display resolution for an in-dash seven inch DVD player at 800x 480 resolution. This exceeds the DVD resolution of 720 x 480. The highest resolution I found for a 7” flip down monitor was 1024 x 768 from Concept, http://www.conceptconcept.com.
More to life than pixels
While pixels are important, there are several other factors that determine good video playback. The most important is off axis response. Off-axis response is the ability of a screen to maintain its visibility as the viewer moves from directly facing the monitor to being located to the side or above or below. In a vehicle, it is most likely that you are not directly facing the monitor. As you viewing angle increases, the video display will eventually deteriorate. Good displays will maintain their picture quality even at extreme angles.
Other important features include contrast and brightness. Brightness is the maximum amount of light a screen can produce. Contrast is the difference between the maximum brightness and the maximum darkness of the display. To maximize these features, companies like Eclipse, http://www.eclipse-web.com, have what they call low-glare screens. Low glare screens minimized the “washed out” effect that occurs when the display is hit with sunlight. There are also displays with black screens to maximize contrast levels. Unfortunately, I was not able to easily find specs regarding off axis and contrast ratios from most manufacturer’s websites. These specs are important because they help us better compare apples to apples between display qualities. Until all manufacturers present these specs, we will have to rely on our informal testing using our optical comparators (our eyes).
All that and the kitchen sink
Not only do monitors have to perform all the demanding tasks required to have good video, they do so strapped with extra features. Today there are many in-dash DVD players that serve as command centers for audio as well as the visual needs. Pioneer, http://www.pioneerelectronics.com takes it one step further by offering vehicle performance monitoring in their flagship model. Also, our media has the ability to deliver two channel, four channels and even up to seven channels of discrete audio output. (Somewhere speaker manufacturers are drooling) Decoders are either built in or available as separate add on units. And the list goes on. The bottom line is that mobile video is the new technology sales opportunity of car audio. Learn it well and reap the sales rewards.
http://www/alpineusa.com
