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Old 22nd December 2010, 02:43   #9  |  Link
manono
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Join Date: Oct 2001
Location: Hawaii
Posts: 7,406
Quote:
Originally Posted by Lyris View Post
Just to clarify Manono, are you talking from the perspective of recompressing already compressed DVDs, or going from broadcast tape formats (or similar) to DVD?
I'm not in the 'biz', if that's what you're asking. My sources are DVDs, all kinds and qualities of retail DVDs. I'm reencoding them for DVD5.
Quote:
Most of the Hollywood DVDs I've seen are lowpass filtered into oblivion and are hardly good from a compression standpoint either.
Yes, I know that, and there are reasons they're forced to do that. One of the major complaints about DVD is the low max bitrate allowed. In addition, often the studios don't even use that max because there are many players out there that won't play compliant DVDs smoothly with the max bitrate cranked up. So you get Warner Home Video setting their max's at 7500. As far as that goes, Criterion is the best because they often allow their max video bitrates to go well over 9000 (and they don't use the Standard Matrix either). Nor do they, as far as I know, low-pass filter their stuff. In addition the studios often try and squeeze in too many DD 5.1 audio tracks which forces the max video bitrate even further down. Or they'll try and put in too many useless extras, compromising the quality of the main movie by forcing down the average bitrate. My guess is these things are forced upon the encoding engineers by a bunch of know-nothings, and the encoders can only work around these constraints. The upshot of all that is, without smoothing the video they're liable to get artifacts, particularly in the complex scenes, and sometimes they do anyway in spite of their best efforts.
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The results are anything but crummy. As I said, using anything else has never produced visibly better results.
There are reasons why the studios don't use it and Dark Shikari touched on one of them when he said, "Therefore, if your average quantizer is "2", the encoder is picking between 1, 2, and 3 (roughly) for its quantizers. This gives it very little precision to work in, because 1 is twice as precise as 2: there's nothing in between 1 and 2 for it to pick. The use of the Standard Matrix for a film on a DVD9 can give you average quants that are too low. I know that seems counterintuitive, but it's true. In addition, the whole point of choosing the proper quantisation matrix is to allow the detail removal to take place in the higher frequencies (the lower right of the intra and non-intra matrices), where it's less noticeable. By using the Standard Matrix, or even the MPEG Matrix (as CCE calls them), you're getting unnecessarily high numbers, the 16s, 17s, 18s, etc., in the lower frequencies (the upper left) where the detail removal is much 'cruder', much more obvious. Compare the upper left numbers from those 2 matrices with those from a matrix such as the Fox1 available in HCEnc.
Quote:
Can you give me some examples of Hollywood DVDs you think are good?
The Fox DVDs are pretty good. It's not a Hollywood studio, but Criterion produces about the best DVDs of all, I think. Except for them dropping to video at chapter stops a lot of the time, which can mess with a lot of DVD players.
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I'd love to know more about what alternative matrixes you'd recommend, and in what circumstances.
I know a bunch but, as I mentioned, it depends on the final average quant. You certainly have a lot more leeway if encoding for DVD9 and don't go overboard with the audio tracks and the extras. As I mentioned earlier, and as kolak reenforced, if you don't want to mess with matrices at all, just use the Standard Matrix but at the same time allow for Q-Matrix Switching. Then, when all done, go back and check how often the Standard Matrix is actually used, as opposed to the ones with the numbers halved or quartered. If you're lucky, you may not see it at all, or only during the most complex of scenes. Make sure and run an extra pass or two, to allow the matrix switching to be optimized. If you want to try, HCEnc has the good Fox1 matrix (aka Fox Home Theater), which Fox used to use but now, for the most part, they use an even better one. If your file size allows for it (the final average quants are low enough, maybe 4-6 or so), it'll create very nice results.

Last edited by manono; 22nd December 2010 at 07:56.
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