Originally Posted by AndrewWong
Just managed to confirm that the ABT102 seems to do the following with 480i 60Hz or 576i 50Hz video :
1. When graphics or still picture is put on screen, I see a huge amount of edge chroma noise (ICP/CUE) on the edges of text, and whatever image is on the screen goes really aliased ( like what you see digital zooming in on a pic )
2. As soon as credits start rolling, the ABT102 locks on and the edge chroma noise disappears and the still image that was on the screen goes smooth and clear again.
I've also seen the same behaviour on a broadcast MPEG2 SDTV (576i 50Hz) stream output from my STB via component.
I could believe that my Pioneer DV-733/47Ai CUE is so bad that the VP30 can't fix it completely, but the blocky image still problem was a surprise. And to see the same thing on a broadcast MPEG2 stream also makes me wonder.
I now have a DVD that can repeatably do it ( US Region1 480i 60Hz Thomas Tank Engine : Percy's Chocolate Crunch Track 9 ).
I took a look at chapter 9 on this disc. Everything you're seeing (well, almost everything) is in the source material on the disc. Here's what's happening:
1) On the still frame at the start of the chapter, the aliasing is all in the source. It looks like a combination of 2 factors. The main one is that the background image appears to have been created from a single field with simple line replication. There looks to be just a bit of ICP in this as well (this is the one thing not directly encoded in the source material), which makes it a little less obvious by imparting some visible line structure into the image.
The vast majority of the noise on the text is cross-luma artifacts (sometimes called dot-crawl, hanging dots, or chroma-crawl), not ICP or CUE. This is an artifact caused by the high frequencies around sharp color transitions bleeding into the luma component, and it occurs when the combined luma and chroma in a composite video signal is imperfectly separated. This disc was mastered from a composite source using what appears to be a mediocre Y/C separator. The cross-luma artifacts are encoded right into the video stream stored on the DVD. You can see these artifacts around any part of the image with very saturated colors (e.g., the yellow letter "1" and the red pinstriping on the train); they appear as a moving checkerboard pattern.
2) There's an interesting transformation which occurs between the still frame and the start of the rolling credits. The background image slowly morphs from the line-replicated image to a smooth looking image over the course of ~8 frames. It's not a hard switch. The scrolling credits are now moving so the ABT102 deinterlacing the moving text based on a single field of data. This reduces the visibility of the cross-luma artifacts around the text (which are still there).
I observed all this in several configurations:
A) Both an S-Video and an HDMI 480i signal from an Oppo 970 to a VP30 with an ABT102.
B) An HDMI 480i signal from an Oppo 480i to a VP30 with an SiI504.
C) Looking at the decoded data from the DVD on my computer frame-by-frame. This was done by extracting the chapter in question, decoding the MPEG 2 data, and examining the resulting sequence of frames in both QuickTime and frame-by-frame as single images in PhotoShop.
It is not the ABT102 (or any other deinterlacer) creating the problems you're seeing on this disc. They're encoded directly on the disc and would be visible with almost any video processor. (You might be able to get rid of some of the Y/C separation artifacts by sending a composite signal from the DVD player to a processor with a 3D Y/C separator in the video decoding front-end.)
As this is the only source material you've specifically called out that I can look at, I don't know if you're seeing the same type of behavior from your other sources as well. It's certainly possible, and probably likely. I saw the aliasing type of artifact on one other DVD source noted in another post in this thread - "Baby Einstein". (What is it about kid's shows that they all seem to have this lousy mastering?) Cross-luma artifacts are, unfortunately, all too common on TV shows transferred to DVD. You may be seeing some Y/C separation artifacts from analog broadcast sources if you feed a composite signal to the VP30, as it has an adaptive 2D Y/C separator which will not be as effective at eliminating these artifacts from still images as a 3D filter. You mentioned that you're using a digital STB, though, so it's more likely a head-end problem.
- Dale Adams