Results: Video Processing
This is a new area in our benchmark suite, so I’ll explain the results as I go. We use a series of pass/fail tests to determine the ability of an HDTV to process different kinds of video signals. Most of the time, you should let your source components do this because they're more capable. If you have an Oppo Blu-ray player, for example, it will exceed the processing ability of pretty much any display. If you set your player to output 1080p video, the display does no video processing whatsoever. An example of the reverse would be a cable or satellite receiver, which is usually poor for scaling and deinterlacing.
The first tests consist of a group of video clips from the Spears & Munsil HD Benchmark Blu-ray Edition, which is available to anyone online for about thirty bucks. Here’s a quick rundown of what's covered:
2:2 pulldown: This is the cadence most commonly found in content shot on a video camera, like a concert or sporting event. The original image is interlaced, two fields per frame. The display must integrate the two fields into a single progressive frame.
3:2 pulldown: The cadence most often used to convert 24p film to 60i video, its order is two fields of the first frame and then three fields of the next, in alternating sequence. If the display doesn’t integrate the extra field properly, there is a very obvious artifact that shows in our test clip and results in a failure.
Accepts 24p: Film content on Blu-ray is encoded at 24 frames per second, and all current players can output the signal at that rate. Most displays can accept this signal and process it to a refresh rate that’s a multiple of 24 by the use of repeated frames.
- 2:2 pulldown - FAIL
- 3:2 pulldown - FAIL
- Accepts 24p – PASS
The 50L7300U failed the two most common de-interlacing tests. If you have DVDs in your library, or if you hook up a cable or satellite receiver, we recommend letting your source devices take care of the video processing. The TV does process 24p content correctly. If you set the ClearScan option to Off, each frame is repeated five times.
The second group of tests covers an HDTV’s ability to show signals below black and above white. Unlike PC signals, which range from 0 to 255, a video signal truncates that to 16-235. The areas above and below those values are considered head and toe room, and are not used in correctly-encoded content. It is desirable, however, for a display to be able to show the levels between 0-34 and 236-255. It makes calibrating levels easier and occasionally content does stray outside the limits.
The Chroma Burst pattern shows a series of single-pixel lines, in color, to determine if a display actually achieves its maximum native resolution. Most HDTVs return different results for RGB signals than for component (YPbPr) video. 4:2:2 is the minimum bit depth output from a source; 4:4:4 is more common. Some players can output RGB, which usually eliminates a conversion step in the display. Our test shows which signal mode provides the best resolution performance.
|Above White||Below Black||Chroma Burst|
Signals below black and above white are passed correctly in all three modes. Unfortunately, the only mode that passes the one-pixel burst test is RGB, and some Blu-ray players don’t support that signal format. If that’s the case, you won’t see maximum resolution from the 50L7300U. If you can use RGB, there is no loss of resolution.