Explaining Video "Number Soup"
By Jerry Del Colliano
Our recent story talking about the various numbers associated with todays video systems was well received, yet many AVRev.com readers have asked for a more detailed explanation of the numbers and how they relate to their systems. And when AVRev.com readers ask they receive.
480i video is the standard for traditional TV, which we have known and loved for years, or at least until we first saw HDTV and immediately wondered why all TV isnt HDTV. 480i is best known as the NTSC standard for standard-definition broadcasts. DVD players traditionally output 480i (the i standing for interlaced) video, unless they are progressive DVD players, which means the player has a video processor that doubles, processes or basically improves the overall quality of the video output. The PAL counterpart to 480i is 576i.
Many of todays video devices output a progressive video output, which looks more smooth and lifelike to many reviewers and critics. These devices include DVD players, DVRs, servers and beyond.
480p video is improved over 480i incrementally and, if given the choice between 480i and 480p, you would always pick 480p. However, todays HDTVs can take much higher resolution inputs, so many systems and components have native rate scaling, which allows you take nearly any video signal and scale it to the native rate of your HDTV, whether it is a 720p-capable device or a 1080i-capable TV or even a newer, more resolute 1080p set. The PAL counterpart to 480i is 576i.
Scaled video looks better than standard definition in almost every case, but the fact that a signal is progressive isnt always good news. If you are using a video processor like ones from Faroudja or DVDO to improve your video, making them have to break down the progressive SD video before scaling it gives them a harder task. Both systems, especially DVDO, have nifty processing for situations when, say, your cable box outputs a progressive SD signal for most channels, but you want to scale it to 1080p video for your new HDTV.
Now we are talking about HDTV. There has been much debate over whether 720p (progressive) is better video than 1080i. I have seen video shootouts at labs that make a compelling argument that both are just fine for even the discerning eye. The question is why two standards would be embraced for HDTV. Seemingly, it would have been simpler to adopt just one, but that is not where we stand today.
ABC, ESPN and others use 720p, which matches the native resolution of many of the early HDTV projectors and monitors that are currently installed in the marketplace. Native 720p video looks better to most than 480p scaled material or even most scaled video from 480i to as high as 1080p. There is a lot you can do to improve video with a good video processor, but you cant turn standard definition into high definition. However, you can make standard definition look significantly better with video processing.