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DTS-HD and Dolby TrueHD

Discussion in 'High resolution audio' started by diabolos, Apr 5, 2006.

  1. wilkes

    wilkes Regular member

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    Yes. Naturally lossless is always lossless, but DTS-HD isn't necessarily lossless. That's the whole point.
    The DTS-HD stream can be anything from "standard" core DTS right the way up to DTS Lossless - through DTS-ES and DTS 96/24 along the way.
    You get a single file that contains the "core" at 24/48 or 16/48, depending on source. The extended frequency response, the additional channels & the lossless component are all taken care of in the extensions.
    So one stream doesall - and the decoder will always decode to the highest quality it is capable of.
    So, for example.
    Suppose I take a 7.1 surround stream, at 24/96 resolution, and encode to DTS-HD Lossless.
    If your amplifier cannot decode the DTS-HD Lossless stream, or the 2 additional channels, but is capable of DTS 96/24 then you will get out a 5.1 stream at 24/96.
    If you have a really early decoder that cannot handle the ES or the extended frequency responses, you'll get a payload output of 5.1 at 24/48.

    I'm not saying it won't have industry-wide acceptance. What I'm trying to say is that I can see other problems that so far are not being addressed by Dolby:
    1 - Only HD DVD has mandated support for Dolby True HD, and that is mandated for stereo only, not multichannel.
    Dolby are arguing that future players should be capable of decoding multichannel lossless True HD, but there are a lot of mights and maybes in there.
    (It's not mandated for Blu Ray at all - it's purely optional.)
    DTS-HD is fully mandated on both formats, although the lossless extension is again optional only.
    2 - Dolby True HD uses 2 streams, so it has the core stream in Dolby Digital and what was MLP. The DD+ is in the extensions (and also, it must be said, optional for BRD) - but we still have 2 streams here where DTS are doing it all with one single stream.
    DTS are just making things a lot simpler - one stream does all, across all formats.

    In all honesty, I have yet to actually see the Dolby encoder. It's Mac OSX only right now, and whilst they hope to get a PC version, it's not on the cards as yet.
    I will be getting the DTS-HD encoder as soon as it's available.
    It's also much, much cheaper too.
    DTS-HD MAS will be around $1500, and that gets you the full encoder, plus a player & a set of editing tools as well that will include restriping capability, editing, splitting & joining of streams, all sorts of goodies.
    Dolby True HD, on the other hand, is a whopping $11,000+
     
  2. diabolos

    diabolos Guest

    Ok I understand what you mean.

    So DTS-HD's lossless codec is an extension instead of another stream. While TrueHD has the DD core with DD+ extensions and then a 2nd stream for MLP.

    In the white paper Dolby says that doing it there way is better because sound artifacts are not audible in the lossless stream that would be if it was simply matrixed as I understand the DTS-HD lossless stream is. Is it safe to assume that you diagree with Dolbys claim? My response to Dolby would be, "if that where true then why has the DTS camp done it that way and had more success (thus far) with DTS-HD than you have with TrueHD"?

    Thanks for the clarifacation Wilkes,
    Ced
     
  3. wilkes

    wilkes Regular member

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    I'm not too sure what Dolby mean by "matrixed" - from a mix engineer & Surround producer's viewpoint the term "matrixed" means something like this:
    There are 2 types of surround stream, discrete & matrixed.
    Discrete is where each channel is encoded individually, and plays back as mixed.
    Matrixed is like the old Quad SQ/QS system, or LCRS, or Dolby's own ProLogic/ProLogic II system, or SRS Circle Surround, where what you end up with is a matrixed stream that plays in stereo on a stereo system and decodes back into 5.1 in a surround system.
    The trouble is that what gets decoded isn't discrete, and you get artifacts like crosstalk, panning issues (Try panning 2 sounds in opposite directions and matrix encoding. The soundfield will collapse into very narrow field)

    What it appears Dolby have done is split the stream into 2 - one is the traditional Dolby Digital stream, the other is the lossless MLP stream. They also use extensions to the stream to get the Dolby Digital + component across.
    My guess as to why it has been done this way - and it IS a guess - is because Dolby Labs didn't invent MLP. Meridian Audio did, and I strongly suspect that the requirement of an independant stream here is for one (or both) of 2 reasons:
    1 - The licensing agreement with Meridian Audio states that the Lossless stream stay independant to maintain integrity
    2 - The decoders require the stream to be independant.
    I may be well wide of the mark - this is a guess.

    DTS used a different approach.
    Nothing is matrixed in the DTS stream at all. At least, not according to the usual meaning of the word when applied to surround encoding.
    Also, remember DTS developed this algorithm over a period of time, and chose to make things fully bavckwards compatible by adopting the extensions approach. I Think this was the right way to go, as one stream does all resolutions and all formats all at the same time.
    I've not used the DTS-HD Lossless encoder as yet, the best I can do right now is DTS 24/96 or DTS-ES 5.1/6.1 where there is a hint of matrixing going on, as with DTS-ES 5.1 you can elect to matrix the Cs channel into the Ls/Rs channels as opposed to the DTS-ES 6.1 method where the Cs channel is truly discrete. That is as far as DTS matrixing goes.

    Finally, as an interesting aside, it is mentioned earlier that "Dolby have an industry-wide reputation".
    So do DTS!
    DTS marketing is that good I have recently run across a lot of DVD-Audio owners who have been playing the DTS stream over the MLP stream because they actually believed the DTS stream was the highest quality option on the disc
     
    Last edited: Jul 7, 2006
  4. wilkes

    wilkes Regular member

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    Now I am looking at that referenced white paper.
    Interesting.
    Dolby are using the same approach as DTS with parts of this.
    They too are using the "Core plus extensions" approach in the Dolby Digital & Dolby Digital + codecs.

    I see nothing in there that convinces me it's any better than DTS-HD Lossless is.
    If anything, DTS-HD Lossless is actually even more advanced.
    I'll try to dig out some white papers.
     
  5. diabolos

    diabolos Guest

    That's intresting. People can argue DTS vs Dolby all day long but DTS better than MLP, now that is something.

    Awsome I love Whitepapers! (j/k)
    Ced
     
  6. wilkes

    wilkes Regular member

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    Ced.
    I am really serious!!
    Been taking some support calls, for one reason or another, and trying to get people with DVD-A players to NOT play the DTS stream where available as the MLP is higher quality.
    You would be appalled at how many there are who genuinely thought the DTS was superior.

    DTS have some good PR!
    Yet how many have heard of MLP?
     
  7. diabolos

    diabolos Guest

    True.

    Ced
     

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