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Requesting Industry Expert Answers

Discussion in 'Blu-ray players' started by Kaphis, Jun 28, 2007.

  1. Kaphis

    Kaphis Member

    May 3, 2006
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    I am a 3rd Year Electrical Engineering Student at UBC. I am writing a formal report on Blu-Ray Disc and HD-DVD. We are required to have an interview with an expert in the industry. If you work in the industry or consider yourself an expert in the area, please answer the following questions for me. Thank you very much.

    Please also PM me your information and a little background as to why you consider yourself an expert. I will include that information in my report and have you as reference so please pm me your full name and an email address for contact.

    If you do not wish to give me your contact, feel free to answer the following questions too if you consider yourself an expert on the topic.

    1) What is the motivation motivation HD-DVD/Blu-Ray development?
    2) Why a blue laser and not a shorter wavelength laser?
    3) What are some design challenges during the HD-DVD/Blu-Ray design process?
    4) Why does blu-ray use a thinner disc compared to other DVDs and HD-DVD? What is the advantage and disadvantage of a thinner disc?
    5) What the technical differences between HD-DVD and Blu-Ray Disc?
  2. JoeRyan

    JoeRyan Active member

    Dec 2, 2003
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    1) motivation--a new format means a new royalty pool and more revenue. It allows manufacturers to sell new products and content owners to reissue their programs for a third or fourth time with little investment other than the cost of mastering and production of media.

    2) blue laser--new royalty pool again. High definition programming could have been issued using a red laser, but that would have meant using older patents as well as eliminating extra features on discs. There is a high definition format in Taiwan and China using red lasers and MPEG-4 compression. Sony/Philips/NEC/Toshiba wanted to issue new patents and incorporate lots of extra features such as the ability to purchase a leather coat just like Indiana Jones's while watching the movie because someone convinced them that that is what the public wanted. (The same public is watching NTSC TV on HD monitors and believes it's HD.)

    3) challenges--A) HD-DVD--molding the substrate and manufacturing the glass masters and stampers well enough to produce the incredibly small pits and tracks. The object was to use MPEG-4 compression all along, and that meant enormous capacity was not required. B) Blu-ray--same as HD-DVD except that initially MPEG-2 compression was planned...and that DID mean the smallest tracks and pits considered possible at the time. It also meant an expensive glass lens for the laser instead of plastic to produce the numerical aperature of 0.85 to produce "near field" recording and reading. It also meant that the recording layer was going to be as close to the lens as possible, and that necessitated a protective cartridge just like the widely accepted DVD-RAM disc. Whoops! DVD-RAM was a dud. Forget the cartridge; let's try a microsilica hard coat and hope no one notices. Whoops! HD-DVD went to MPEG-4. We can do the same and not need the extra 10-20GB unless we can convince people that the "cutting edge" storage of 50GB is great for archiving and putting all their eggs in one basket. Now we just have to convince all the duplicators that entirely new mastering and production equipment will be a good thing. They can replace all their old equipment used for DVDs and HD-DVD.

    4) The Blu-ray disc is the same thickness as DVD and HD-DVD and CD for that matter. It is the recording layer that is so thin because it is face to face with the laser pickup head. The advantage is that it allows near-field recording to get the smallest pits and tracks and read/write the most data. The disadvantage is that the lens is much more expensive, the surface has to be protected, all the assembly equipment must be new, and there is greater danger of damage to both the recording surface and the pickup head.

    5) There are scores of differences, but the most significant is that the HD-DVD disc is based on the structure of the DVD with the recording surface sandwiched in the middle while Blu-ray is much more like an upside down CD-R with the recording surface on the very bottom of the disc. The other differences relate to programming functions, software architecture, and writable media based on either organic dye or metallic compounds.
    Last edited: Jul 5, 2007

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