Dual, Double Layer DVDs & DVD Recorders

Discussion in 'DVD Video' started by Tony McKee, Mar 24, 2005.

  1. Tony McKee

    Tony McKee Guest

    Hi Folks!

    A DVD recorder/player (in this case for a home theatre system - not
    computer) must be specifically manufactured to play and record to
    double-sided /dual-layer DVDs - right?

    Background to the question:

    I'm finally getting around to 'retiring' our trusty ol' VCR and buying a DVD
    player/recorder for the lounge - but just as I'm about to flash the ol'
    credit card at the local department store, the boffins start making
    double-sided and dual-layer discs. "The way of the future!" they shout with

    OK. Sounds finger-lickin' good to me. But I guess it means that nice
    expensive Sony RDRHX900 with its 160Gb hard drive, the ads of which I've
    been slavering over lately, will have to be foregone in favour of the next
    model - or some other manufacturer's offering - which will have the
    capability to play and record to dual and double discs. After all, if one is
    going to fork out that much dosh for a new toy, common-sense suggests one
    might as well get something that will embrace the new media innovations.

    I had a look at the RDRHX900's specs on Sony's web site, but nothing is
    mentioned regarding its ability to accomodate double-sided/dual-layer discs.
    Damn nice recorder all the same.

    Of course, this time next year, the boffins will probably come out with
    triple-layer discs.... sigh...

    Any advice, ideas, observations or ruminations welcome. ;-)

    Cheers, Tony McKee


    I am a part of all that I have met... yet all experience is but an arch
    Wherethro' gleams that untravel'd world whose margins fade
    Forever and forever... 'ere I move.

    ===-- Ulysses --===
    Tony McKee, Mar 24, 2005
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  2. You should get a DVD recorder capable of recording dual-layer discs.
    Although the discs are expensive now they eventually should come down in

    Any DVD recorder or player should *play* dual-layer discs as they conform to
    the DVD9 specification (many commercially pressed movies are DVD9

    I know of no "dual sided" recorders. There are dual-sided discs but you
    simply take them out and flip them over to play the other side. (like vinyl
    records, if anyone remembers those).
    High Definition DVD recorders and players are next up on the horizon.
    There's always something better around the corner....

    Steven de Mena, Mar 24, 2005
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  3. Correct. In fact, you cannot actually buy a HX900 in thhe UK anymore -
    Sony have declared it obsolete after only four months!

    The replacement (in the UK at least) is supposed to be the HX910,
    which is out already in some other European countries and apparently
    sports a 250Gb HDD and dual-layer writing. An announcement is


    The Doctor Who Restoration Team Website
    Steve Roberts, Mar 24, 2005
  4. Tony McKee

    Tony McKee Guest

    'Great Scot!' - as the Doc used to say. Four months, down the hatch, - and
    back to the future already! I'm in New Zealand and the HX900 has only just
    become available here.
    Goody goody gumdrops. Will look forward to that one. Will sheath the credit
    card and slaver a little longer. ;-)

    Cheers, Tony McKee


    I am a part of all that I have met... yet all experience is but an arch
    Wherethro' gleams that untravel'd world whose margins fade
    Forever and forever... 'ere I move.

    ===-- Ulysses --===
    Tony McKee, Mar 24, 2005
  5. Tony McKee

    Tony McKee Guest

    I didn't know that. Ta muchlee for the info.
    Life is so short... and so many corners... but sooner or later one has to
    draw the credit-card. ;-)

    Cheers, Tony McKee


    I am a part of all that I have met... yet all experience is but an arch
    Wherethro' gleams that untravel'd world whose margins fade
    Forever and forever... 'ere I move.

    ===-- Ulysses --===
    Tony McKee, Mar 24, 2005
  6. Tony McKee

    Brian Guest

    In the technology world there will always be better equipment. The
    computer is a good example. Look how far the computer has developed.
    At the moment you can get 2 hour of good quality video on a DVD which
    satisfies most people. I've heard nothing about duel layered DVD
    recorders. There is some development in blue wave recording that
    claims to fit more video on a DVD at the same high quality.
    What ever you buy today can be sold later on.
    DVD's are likely to be around for a long time with the many DVD
    players in the world.

    The Sony has a few missing things.
    If you record a movie that's over 2 hours long that you plan on
    putting on to a DVD then you have to record it in the LP 3 hour mode
    (it might be 4 hour mode) which causes the quality to drop. Some DVD
    recorders allow you to record at slight below SP (tandard speed) eg 2
    hours 10 minutes, so you don't lose so much quality. The Pioneer has
    32 different recording qualitys.
    The other problem and one that many don't like is that if you record
    conitinously on the hard drive for more than 2 hours and want to break
    up the recording so you can put the recording on two DVD's (2 hours
    per DVD) there is no function on thr Sony recorder for doing this.

    There are some of the reasons why I returned my Sony RDRHX900 and
    brought a Pioneer 720 DVD recorder.

    take a look at www.dvdrhelp.com

    Regards Brian
    Brian, Mar 24, 2005
  7. A Dual-Layer disc has to have exactly the same amount of information
    on each layer, so that one is always under the other. There is no way
    to predict how much data needs to be recorded before the layer change
    if it is being done "On the Fly," It has to be set during authoring;
    therefore there ARE no dual layer DVD-recorders. Maybe, MAYBE, a unit
    with a Hard Drive might include the ability to properly subsequently
    record to a dual-layer DVD from the HD, but I haven't heard of that

    All DVD players can play dual-layer, though some have trouble with
    home-authored dual-layer DVDrs.

    ... Steve ..
    Steve(JazzHunter), Mar 24, 2005
  8. Tony McKee

    pertnoy Guest

    Right, so why not wait till the media comes down in price,the player will
    come down in price too.
    pertnoy, Mar 24, 2005
  9. I can't help but think that you are wrong! For starters, dual-layer
    discs don't have equal data areas on each layer in any case - one is
    4.7Gb, the other is 4.3Gb.

    Dual-layer DVD burners for PCs have been around for at least a year
    and there are dual-layer DVD recorders on the market already, such as
    the Sony HX910 and HX510. The former does have a hard drive, but the
    latter does not... therefore it MUST be able to record on the fly onto
    both layers.


    The Doctor Who Restoration Team Website
    Steve Roberts, Mar 24, 2005
  10. Tony McKee

    Oldus Fartus Guest

    Are you sure of that? Both of those recorders have a hard drive, but
    regardless of that I can not find anything to indicate they can record
    dual layer. Perhaps you could post a link?
    Oldus Fartus, Mar 24, 2005
  11. I do not believe that statement is correct. Can you provide some evidence
    of this?

    Steven de Mena, Mar 24, 2005
  12. That statement is correct. ANY technical description of dual layer
    DVDs indicates that the data must be precisely recorded on both
    levels. It can not be on just the top and not the bottom or
    vice-versa at any point since at the point when one ends it would
    change the information used to keep the laser pickup in focus. The
    layer density between the top surface and bottom recorded track would
    greatly change by as much as 50% The "Scattering"of the beam would
    change just as would be the caused by the appearance of a bad smudge.
    The amount of data recorded on each layer is slightly different due to
    run-in and layer-change and EOD information outside of the actual
    data. A bad burn results from the authoring program and/or writer
    firmware not properly recording "garbage" if necessary to make the EOT
    end under the beginning of the disc. Naturally I can't find a
    specific link regarding this now that I'm looking for it, since actual
    discussion of the hardware is predominant, but matching recorded areas
    for both layers is a definite part of the dual-layer specification.

    ... Steve ..
    Steve(JazzHunter), Mar 24, 2005
  13. This link gives an indication of what I mean. Note the diagrammatic
    layout at the bottom of Parallel and Opposite track paths and how the
    layer change must take place at one point (obviously) and the leadout
    is used to bring the End Of Disc back under the ID track so that the
    Bottom Layer is ALWAYS, including at First Play, being read through a
    recorded top layer.


    ... Steve ..
    Steve(JazzHunter), Mar 24, 2005
  14. Have a look at this paragraph from the article posted above...

    "The two layers represent one contiguous address stream for recording
    as a Video Disc, a DVD-ROM, or even a packet recorded disc. When
    recording on dual layer media, the drive first records on the first
    recordable layer L0 from the inside hub area outward, just like a
    typical DVD recordable disc. When the end of information recorded in
    L0 is reached, Middle Zone 0 is added. Next, the drive focuses on the
    second recordable layer L1 to create Middle Zone 1 that over-wraps
    Middle Zone 0. The disc is then recorded from the outside rim inwards.
    Multi-session discs can be recorded with dual layer recordable media,
    so it’s possible to add data in “sessions” on a disc."

    Note the last sentence! This is stating that the two layers do not
    have to contain the same amount of information - you can stop the burn
    and subsequently add more data in a later session.

    I agree that you cannot record on L1 unless L0 is full however! But
    aside from that, DL works by simply writing until L0 is full and then
    switching to L1. You can fill L0 and then just burn 10% of L1 if you
    wish - that's perfectly valid!


    The Doctor Who Restoration Team Website
    Steve Roberts, Mar 24, 2005
  15. Looks like I was making a bit of assumption about the 510, but the 910
    is certainly dual-layer. It's not been released in the UK yet, but it
    has been in other European countries, so some links to those...



    I leave you to translate - but the dual-layer bit is clear!

    Interestingly there sems to be a HX-710 on the way too - 160Gb like
    the current HX900, but dual-layer capable.


    The Doctor Who Restoration Team Website
    Steve Roberts, Mar 24, 2005
  16. Steve Roberts, Mar 24, 2005
  17. Tony McKee

    Darrell S Guest

    Perhaps they meant double layer rather than dual sided. I have one. It's
    a Sony DVD recorder DRX-71OUL. It's USB 2.0 and will do DVD +R, +R double
    layer, +RW, -R, -RW, DVD-ROM, and DVD Video. I spent the extra money to get
    it so it will be compatible with just about any media of DVD that becomes
    the winner.
    And there's also Blu-Ray which further complicates things.

    Darrell R. Schmidt
    B-58 Hustler History: http://members.cox.net/dschmidt1/
    Darrell S, Mar 24, 2005
  18. The Philips standard still calls for layer 0 to be covered by a
    recorded Layer 1, or nothing at all, so I can't reconcile the
    article's last sentence unless a "Placeholder" format is done to the
    not-yet-used portion of layer 1. If in fact the remaining part of
    Layer 1 is not recorded at all then that would explain why many
    players do not handle dual-layer DVDr properly since it is in fact not
    being done to the Philips commercial dual-layer standard.

    ... Steve ..
    Steve(JazzHunter), Mar 24, 2005
  19. Tony McKee

    Alpha Guest

    This is how I read the spec for dual layer as well.
    Alpha, Mar 24, 2005
  20. Tony McKee

    Oldus Fartus Guest

    Thanks for that Steve.

    Interestingly, Sony itself makes no reference to the 910 on it's own
    website, but I found enough other references to confirm what you said.

    I can recall the same discussion the other Steve mentioned, about dual
    layer home burning requiring the same amount of data to be on both
    layers, so he was not mistaken. I can only guess that either the
    technical reasons were eliminated, or as someone else suggested, the
    dual layers are recorded from the hard drive rather than on the fly.

    Whatever the reason though, it does seem dual layer home recording is
    most certainly here.
    Oldus Fartus, Mar 25, 2005
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