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    Random Poll: Just how big is big momma?


    a) Big momma is so big, she can get group insurance rates.
    b) Big momma is so big, she gets clothes in three sizes: extra large, jumbo and oh-my-god-it's-coming-towards-us!
    c) Big momma is so big, when she gets on the scale it says 'to be continued.'
    d) Actually, big momma is so big, when she gets on the scale it says 'One at a time, please!'
    e) Hey... uh - the movie is about 'Big Momma' not 'Yo Mama'. Get your head out of the toilet.

    Submit A Poll Question

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    See our responses!

      DCN DVD VIDEO FORUM
      Technical Know-How
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    Author Topic:   Overview
    Mystchif
    Lackey

    Posts: 14
    From:New York, NY
    Registered: May 2000

    posted 05-23-2000 12:10 PM     Click Here to See the Profile for Mystchif     Edit/Delete Message   Reply w/Quote
    The following link is a general overview of the DVD process. We'll try to examine these in depth later on.
    http://www.DVDExperts.com/education.htm#dvd101

    Edge
    Big Cheese

    Posts: 147
    From:Sunnyvale, CA
    Registered: Dec 99

    posted 05-24-2000 12:26 PM     Click Here to See the Profile for Edge   Click Here to Email Edge     Edit/Delete Message   Reply w/Quote
    Okay.. I've got an immediate question.

    This is in regards to layer changes.

    Now Jhodes... isn't it correct that you worked on the Casino disc from Universal at one point or another? That disc has a perfect layer change in that it's undetectable.

    What exactly goes into a layer change that can vary the results so well? I know that the player buffering abilities must be part of it... and the mastering of the disc the other... but why hasn't the technique for "Casino" been adopted by others and utilized on every dual layer disc now?

    I've seen some pretty poor layer changes, not to mention that these layer changes are on DVDs that have yet to come out.

    Thanks!

    - mf

    codestah
    Big Cheese

    Posts: 108
    From:San Jose, California USA
    Registered: Dec 99

    posted 05-25-2000 01:25 PM     Click Here to See the Profile for codestah   Click Here to Email codestah     Edit/Delete Message   Reply w/Quote
    quote:
    Originally posted by Edge:
    What exactly goes into a layer change that can vary the results so well? I know that the player buffering abilities must be part of it... and the mastering of the disc the other... but why hasn't the technique for "Casino" been adopted by others and utilized on every dual layer disc now?

    Geezuz! Amen brutha, amen! I'm going to guess that it has to do with data seek alignment at the sector level which is beyond the comprehension of most multimedia producers.. tell me how far off base I am!

    Mystchif
    Lackey

    Posts: 14
    From:New York, NY
    Registered: May 2000

    posted 05-26-2000 10:06 AM     Click Here to See the Profile for Mystchif     Edit/Delete Message   Reply w/Quote
    In the same way that every film is different, every layer break will be different as well.

    There are a lot more factors that go into a layer break placement besides a beautiful fade-to-black scene. The size of the movie, the extras on the disc, which layer the extras exist on, and some other more techie aspects of video.

    In some cases, the layer break may be placed in such a way that it is virtually unnoticeable (eg. Casino). This particular disc had very little extras, and, most importantly, the feature had many scenes throughout that went to black. This is the ideal case, otherwise, motion is paused during layer change (eg Contact).

    There is no way to make every disc behave as Casino did, but all we can do is work with what we are given.

    As you mentioned above, the way different players handle the layer change may make a layer break look worse than it actually is. Of course, consumers are not going to run around and test the disc on every player they can get their hands on, that's the developer's job.

    So really, there is no way to make all layer changes the same. There are just too many factors involved to use Casino as a template for all others.

    Edge
    Big Cheese

    Posts: 147
    From:Sunnyvale, CA
    Registered: Dec 99

    posted 05-26-2000 02:34 PM     Click Here to See the Profile for Edge   Click Here to Email Edge     Edit/Delete Message   Reply w/Quote
    Despite the technical issues involved in the creation of the DVD... logic would indicate that hardware manufacturers would increase the size of the buffer in a way that would allow the player time to decipher a layer change (or receive a flag notice indicating 'Hey, wake up! I'm a layer change!') and then adequately remove it from the buffered presentation for seamless audio/visual playback.

    Does that seem fathomable down the road from your end?

    Another concern is that during layer changes, the video isn't always the most noticable distraction... but the complete drop in an audio signal to the receiver. This in essence drops the decoding process at the receiver and returns a dead silence to the surrounding speakers for a split second.

    Is it not yet possible to keep some sort of signal delivery open between the player and the receiver/decoder during the point of changing layers?

    - mf

    [This message has been edited by Edge (edited 05-26-2000).]

    Mystchif
    Lackey

    Posts: 14
    From:New York, NY
    Registered: May 2000

    posted 06-05-2000 02:58 PM     Click Here to See the Profile for Mystchif     Edit/Delete Message   Reply w/Quote
    To be perfectly honest, I really don't know how to respond to your questions regarding players. I really don't deal with, nor understand fully, the hardware that goes into dvd playback.

    Logic would indicate, however, that hardware manufacturers would provide enough buffer to compensate for a layer change.

    I agree with your comments above, though. Until we have answers from those involved in player manufacturing, we can only speculate.

    codestah
    Big Cheese

    Posts: 108
    From:San Jose, California USA
    Registered: Dec 99

    posted 06-05-2000 03:41 PM     Click Here to See the Profile for codestah   Click Here to Email codestah     Edit/Delete Message   Reply w/Quote
    Well, speculating or not, I can say with some multimedia and design experience that with a large enough read-ahead buffer applied, layer change delays would disappear completely. I hypothesize that most current players only buffer enough data to facilitate even-rate data streaming. The amount of memory that would be needed to fill a buffer with content which covers the amount of time needed to perform the mechanics of the layer change would be great enough as to lend significant addition to both cost of development and production, both of which would be visible in the product pricing. Not having even SEEN any of the VERY high-end DVD players available, it is possible that this is already being done.

    Anyone know for sure?

    Edge
    Big Cheese

    Posts: 147
    From:Sunnyvale, CA
    Registered: Dec 99

    posted 06-10-2000 07:40 PM     Click Here to See the Profile for Edge   Click Here to Email Edge     Edit/Delete Message   Reply w/Quote
    The majority (by far) of responses to our poll regarding the quality of DVD layer changes on DVD players indicated that the majority of voters had DVD players that displayed layer changes with a brief pause in playback.

    - mf

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