In reply to:
About black level, a good DVD player will be able to produce true black, however, many DVD players, such as the Samsungs, cannot reach true black.
To get into the technical side on this (and maybe dispel some marketing hype), there are two different levels of black - NTSC broadcast black pedestal is 7.5 IRE, stations broadcasting blacks darker than this can be fined or have their tickets revoked by the CRTC (FCC in US?) analog TVs have circuitry to drop this dark grey to a good black. "Digital black" (R0 G0 B0) is pure black, one of many reasons DVCam/Digi8 (I believe DVCPro is however) is not broadcast legal (but it can be legalized). Digital black is a good pedestal for a digital screen (through VGA/DVI, etc).
Now, DVDs, the ugly little wannabes that they are, the little format that couldn't (can you tell I'm not a fan?) use MPEG-2 encoding, a lossy codec. Of course, the video needs to be compressed to fit on a 12cm diameter disc - but the capacity of the discs has changed since it was introduced - most of the first DVDs I saw were DVD-10s (double-sided, single density, 9.5GB capacity) but since both sides were straight silver, you had to read the imprint on the hub to determine what movie you had in your hand. The great unwashed said this could not be so - that they wanted colour imprints like CDs had, so enter the single sided, single layered DVD-5s we're stuck with now, with twice the compression and half the data. And what is the drawback of having only half the space of a DVD-10 (and a quarter of the largest capacity format - the DVD-18)? MPEG-2 works on I,P,B frames (intracoded, predictive, bidirectional) and macroblocks within the frames. Intracoded frames are compressed as a full frame, predictive and bidirectional frames are actually just "what has changed since the previous frame (for P) and the previous and next (for B)" in each macroblock - the smaller capacity of storage the video has to fit into, the higher the compression (like a crunchy JPG image) on the I frames, and the more "differences" the P and B frames have to ignore (which gets compounded every consecutive P or B frame - if a change isn't "caught" by one frame, that error is moved onto the next and next and next frames until another I frame comes up, which gives it a new clean slate to work from).
Voila... crawling blacks, jaggies on diagonal lines, chroma shift. To see the crawling blacks easier - turn off "extended blacks" if possible on your DVDP turn up the brightness on your TV and watch a DVD with a dark section - take Fellowship of the Ring, for instance, when the hobbits are hiding under the log and Frodo uses the ring, you'll see the "black areas" are actually big splotches of different shades of grey that pulse and move. Ugly! To make these less noticable, a lot of DVD players use black clamping, they grab say, the darkest 5%-10% of the visual spectrum and force it to become black, pretty much turning down the brightness, then reramp the gamma levels on the rest of the spectrum to expand it to fill what's left. The jaggies are usually processed away with an adaptive soften filter. And the chroma shift? Only the enthusiasts will notice that, and we only make up a small portion of the market, not enough to worry about - better the perfectionists end up with a crappier product than having Mrs. Smith have to squint to read each DVD hub when her half-wolf child empties the movie collection onto the floor one day and she has to return them to their cases.
The format could have been so much better.
Bren R.
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That I have a lot of experience with.