Dolby SR or S on software ?

Discussion in 'Pro Audio' started by musurgio, Dec 13, 2003.

  1. musurgio

    musurgio Guest

    I really wonder if there is Dolby noise reduction system like SR or S on
    software plugin so you can use it to record on tape recorder that has
    musurgio, Dec 13, 2003
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  2. musurgio

    Pooh Bear Guest

    Interesting idea.

    Theoretically possible.

    It would be essential to have a 'line-up' function on your tape m/c to make
    it work. All Dolby noise reduction methods require accurate rec/rep levels.

    Why not suggest it to Dolby licensing ?

    Pooh Bear, Dec 14, 2003
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  3. musurgio

    Mike Rivers Guest

    Nope. Acutally, what most people want is for the yet nonexistent
    software to work in the other direction - to decode a Dolby recording
    once it's been transferred to a digital format.

    I'm really Mike Rivers - ()
    However, until the spam goes away or Hell freezes over,
    lots of IP addresses are blocked from this system. If
    you e-mail me and it bounces, use your secret decoder ring
    and reach me here: double-m-eleven-double-zero at yahoo
    Mike Rivers, Dec 14, 2003
  4. musurgio

    JoavS Guest

    AFAIK Dolby was never made as a software, nor dBx
    JoavS, Dec 14, 2003
  5. musurgio

    Peter Larsen Guest

    Yes please! - for plain Dolby B too. I needed that yesterday.

    Kind regards

    Peter Larsen
    Peter Larsen, Dec 14, 2003
  6. musurgio

    Peter Larsen Guest

    Just to restore compact cassettes in the home? - what is the license
    cost for the software in a casette deck, 10 cents? - and just how many
    good new cassette decks are available in the shops? - and how many
    stand-alone Dolby B decoders so that one can fix frequency response and
    level issues prior to decoding?

    Kind regards

    Peter Larsen
    Peter Larsen, Dec 14, 2003
  7. musurgio

    umbriaco Guest

    That assumes that the source cassette has retained level and flat frequency
    response through the years. Reality is far different. All tapes slowly self
    erase especially at short wavelenghts. 12kHz on a 1.875 ips tape is very
    short indeed.
    I've a large library of 20 to 30 year old Dolby B cassettes I'm transferring
    to CD. Depending on the tape stock the correction for proper playback level
    / HF eq to properly decode can be quite drastic. It's sometimes necessary
    to add +6dB gain and +6 at 10kHz eq boost to properly decode the NR.
    This is not possible with the controls of the deck's repro amp.
    I've been using an Orban 622B for gain / eq into a Dolby 330 unit.
    Look around. The cassette duplication biz is pretty dead. there must be
    quite a few of these things headed for dumpsters.
    umbriaco, Dec 15, 2003
  8. musurgio

    Peter Larsen Guest

    [quoting me]

    I am not talking dubbing, I am talking copying from one good casette
    deck to my computer what has been recording on various less good decks.
    And the good casette deck I could find in a nearby hi-fi shop was second
    Aha, that explains why those tapes from 1974 sound so muffled, thank
    And for all Ray Dolby's fine ideas about licensing, said fine ideas are
    preventing correct decoding of properly licensed recordings. Also as far
    as patent rights go .... well, they go for 17 years, and then it is a
    free for all.

    There may be something that I do not know about this, but to the best of
    my understanding anybody can write and publish a dolby decoder in
    software if the technology was patented originally. If patent rights
    still exist, then anybody in a country where a patent has not been
    applied for can - in my understanding of this - can write and publish a
    software dolby decoder. Do be aware that I may be wrong on details of
    this this, but patents in my understanding of this apply only where
    applied for and only for their duration and by implication release the
    "art" where a patent has not been applied for and when a patent expires
    into the public domain.

    I will gladly pay Dolby Labs USD 40 for a directX plugin that will do
    dolby b decoding, seems like a fair price. Since they are the ones with
    the knowhow, surely they are the ones that one would expect to be easily
    able to get it right.

    Kind regards

    Peter Larsen
    Peter Larsen, Dec 15, 2003
  9. musurgio

    Scott Dorsey Guest

    So, rent an outboard Dolby B decoder. You will need to use an outboard
    unit to get the levels correct anyway since most internal decoders have
    no way to set dolby levels.
    If anything sounds muffled, I would first look at azimuth problems. No
    cassette deck ever had correct azimuth for more than a few minutes as far
    as I can tell. Just getting the azimuth right and riding it will be of
    more benefit than anything else you can do with cassettes.
    Scott Dorsey, Dec 15, 2003
  10. musurgio

    umbriaco Guest

    I'm not trying to hype up the top of my old cassettes, my scenario is this.
    Many cassettes I made in the '70 were of borrowed LP's (ducks).
    Dual 1228 w/ Shure V15 type III to an Advent 201
    Started off using Scotch "High Energy" tape, then Ampex "20/20+", both
    exibited limited HF headroom during recording.
    Yes, I went through proper calibration of the deck.
    I then moved to Maxell "HD" & "HD-XL" tapes which were pretty acceptable.
    During the course of almost 30 years I've purchased many LP's that I had
    previously taped.
    I now use a Thorens 124 w/ AudioTechnica 440ML & a Tascam 122 MKII.
    Comparing the LP's to the old tapes, the Scotch & Ampex tapes have lost much
    level & HF, the Maxell has held up much better but has still lost some level
    & HF.
    Using the LP as reference, I note what pre Dolby decode level & EQ boost
    gets play back as close as possible to the LP then use those settings as a
    start point when transfering other material from that same stock.
    umbriaco, Dec 15, 2003
  11. And for good reason. Once a product has been digitized, where's the dolby,
    where's the dbx? It's an analog process. How could one expect to transfer
    squeechy, over hyped HF information, digitalize it, and then have some dbx
    or Dolby process to change it. It's part of the process in analog and it's
    not one sided. You don't use Dolby B/C/S or SR only only on the path in.
    It would have to be on the path out, too.

    Heck, buy Dolby SR, run product through it on the way in, mix, run in on the
    way out. Hmmm, just like on tape.


    Roger W. Norman
    SirMusic Studio
    RAP FAQ and Purchase your copy of the Fifth of RAP CD set at
    See how far $20 really goes.
    Roger W. Norman, Dec 16, 2003
  12. musurgio

    Arny Krueger Guest

    Dolby and DBX are actually processes that occur in the time and amplitude
    domains that are to date only implemented in the analog domain. There's
    nothing that says that they can't possibly be implemented in the digital
    domain, and there is a lot of pretty reasonably justification for a digital
    implementation of Dolby and DBX decoding.
    The use of digital low pass filters seems to be in order.
    Right, and implementing a digital-domain Dolby A/B/C/S or SR decoder would
    be a worthy project for some graduate students, at most. Just a bunch of
    digital filtering and digital dynamics processing.
    The problem is that these days finding an analog tape machine in good
    working order to play legacy tapes is tough enough. Coming up with N
    channels of Dolby or DBX decoding in working order is even tougher. What
    about in 10-20-30 years?
    Arny Krueger, Dec 16, 2003
  13. musurgio

    Peter Larsen Guest

    I am not talking albums, I am talking sound effects recordings, for
    instance of the Morris Minor I had back then.

    Kind regards

    Peter Larsen
    Peter Larsen, Dec 16, 2003
  14. musurgio

    Peter Larsen Guest

    An expired patent is expired and that is it. For the duration of the
    patent licensing is required, when the patent expires things end up in
    the public domain. Similarly they end up in the public domain in any
    country where you have not filed a patent *because* you have actively
    omitted to protect them there.

    What they can still license is the *implementation of the process*, i.
    e. chips etc and they can still require a fee for saying "dolby
    He has had his license earnings. Also Ray Dolby do not own the
    recordings that are encoded with the system and preventing decoding by
    not supplying modern decoders, i. e. in software, could be said to mimic
    microsoftian monopolistic behaviour because the encoding in dolby b has
    become a defacto standard for compact cassettes.

    I am all in favour of Dolby Labs coming up with that directX pluging or
    equivalent because they are likely to know the exact behaviour of the
    chips used in the encoders. I don't mind paying them, it is a good
    system and it is well earned. I do mind the that the hardware is de
    facto vanishing.

    Kind regards

    Peter Larsen
    Peter Larsen, Dec 16, 2003
  15. musurgio

    Peter Larsen Guest

    That of course is an option, as is borrowing one and that probably is
    what I will do, an aquantaince mentioned having one.
    Indeed. There was one NAD cassette deck with hf-compensation in the
    playback pre-dolby. Neat.
    :) ... thanks. Fortunately I can rely on most more recent recordings
    being recorded on decks in good alignment and all aligned with the same
    alignment tape.

    Kind regards

    Peter Larsen
    Peter Larsen, Dec 16, 2003
  16. musurgio

    Scott Dorsey Guest

    May not help. Typical cassette decks will not stay aligned for more than
    a few hours of operation. And, if you record to a cassette with a machine
    that is properly aligned, and you leave the cassette in a closet for a few
    years, the shell will deform slightly and the alignment on playback will not
    be correct. You gotta set it up for each side of each tape individually.

    I _hate_ cassettes.
    Scott Dorsey, Dec 16, 2003
  17. musurgio

    Mike Rivers Guest

    So apparently if the patent has expired, any of you folks out there
    who think that programming is easy can have at it. Apparetntly it's
    not as simple as it appears.

    It seems like Dolby A and B shouldn't be too hard, but Dolby SR is a
    bugger. Dolby has said in the past that it's simply not practical to
    attempt to model it in software.

    I'm really Mike Rivers ()
    However, until the spam goes away or Hell freezes over,
    lots of IP addresses are blocked from this system. If
    you e-mail me and it bounces, use your secret decoder ring
    and reach me here: double-m-eleven-double-zero at yahoo
    Mike Rivers, Dec 16, 2003
  18. musurgio

    Geoff Wood Guest

    Yeah, but when they said that acoustic modeling hadn't even been thought of.

    Geoff Wood, Dec 17, 2003
  19. musurgio

    Peter Larsen Guest

    Hmmm, points noted ... it appears that I need an extra cassette deck &
    to check whether that old scope still works ... hmm ...

    Kind regards

    Peter Larsen
    Peter Larsen, Dec 17, 2003
  20. musurgio

    Peter Larsen Guest

    I'm not a patent lawyer, it is just my understanding, and the US of A
    has some real funny patent laws, a plant or bug or cell can have done
    something for 400000 years and it is still new in the magic patent sense
    of that word.
    Slopes and attack and release times are in my unskilled opinion the
    primary concerns and they are the very concerns that would make it easy
    for an original dolby software version to stand against market pressure.
    And with the aforementioned funny patent laws the software
    implementation could be in itself patentable giving them a new 17 year
    "simply not practical" comes with an implicit "for us" and can be
    translated in many interesting ways, none of which actually exclude the
    feasibility of the concept, always check such statements with a
    doublespeak dictionary.

    Kind regards

    Peter Larsen
    Peter Larsen, Dec 17, 2003
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