Additional Benchmark Tests & Conclusion
While the HQV Benchmark may make up a good visible portion of our tests, we also run a series of tests using patterns from AVIA Pro which are intended to check different aspects of the player ranging from the very significant (layer change delay and macroblocking) to the more obscure (rainbow dither). All together this gives us a broad spectrum of tests with which to compare various players and grade them.
We are checking to see that the DVD player output shows full DVD resolution at 6.75Mhz. We are also checking to see how well it scales by observing single pixel spacing around the perimeter of this test pattern. This is typically a pass/fail test.
Using a pixel-accurate test pattern we can determine how many pixels are cropped, if any, from each side of the picture frame. Full credit is given for less than 4 total cropped pixels. More than 7 pixels fails.
Y/C Delay Chart
This test pattern shows if there is any delay between chroma and luma channels on the component video outputs of the player. It shows RGB information as well as Cr and Cb delay in nanoseconds. This is a pass/fail test.
DVD players vary in the amount of time they take to complete a layer change. We test using AVIA Pro's layer change test to time the transition. Full credit is given for anything under 1 second, while anything over 2 seconds fails.
Moving Zone Plate
The Moving Zone Plate tests resolution and deinterlacing at multiple directions and velocities. It is a brutal test and we are looking for players that can handle speeds of +/-3 in all directions. Most players will do fine at a perpendicular speed of 1, but fail (show visible moire pattern) as the Zone Plate is made to move faster or in an angular/circular motion.
Building on the previous Zone Plate test, this adds testing of deinterlacer accuracy and recovery. This represents what players go through during scene edits that alter film cadence or vary between 2:3 and 2:2 (film and video) rates.
The rainbow dither sequence tests for poor temporal dithering. Temporal and spatial dithering is an effective way to increase the effective bit depth of an image, rendering still image gradients smoothly. When these same images are put in motion, however, bit depth may decrease and show visible contouring or banding. As you can imagine, this would affect real-world pictures quite a bit with regards to quick pans and high speed motion. This test pattern is also helpful for quickly evaluating rainbow effects in DLP systems - but that is not being tested or graded in these tests. This is a pass or fail test.
Passes Blacker Than Black
Mentioned earlier, we use a Needle Pulses + Log Scale + Gamma pattern to easily determine if a player can pass blacker-than-black signals (~0-15 IRE). This is very important to achieving a smooth and dynamic
Passes Whiter Than White
Using a Deep Horizontal Ramp pattern we are able to quickly determine if a player can pass whiter-than-white signals (~236-255 IRE).
We use several movie clips and test patterns to determine the amount of macroblocking present in the player. Macroblocking is a natural, known issue with many discs whereby MPEG artifacts are present in areas of solid colors or when fading to and from white or black. Macroblocking occurs in many other instances as well, but the condition is more easily noticeable in these scenarios. This test specifically checks whether or not the player's processing is making these effects worse (failing) or less noticeable (passing). In particular, there are some known issues with specific processing chips that we look for to see how they function.
Is this the extent of our testing? By no means! We also do a series of subjective listening and viewing tests - consisting of material we are intimately familiar with as well as new content to keep the review lively. DVD player (as well as display) reviews are difficult, but we're glad that by adding in some objective-style tests we're able to quantify more of our overall ratings and deliver consumers the additional information that will help them in making a decisive purchase.
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