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  1. #11
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    Quote Originally Posted by Wombat View Post
    @Archimago
    I did no indeep reading leave alone understanding of that patent so i may be wrong.
    A blind quote that may not describe how the realworld implementation works:
    " The listener with access to all 24 bits may use the decoder of figure 5B to enjoy full bandwidth lossless reproduction of the 13-bit signal at point "A", i.e. with a resolution of 17 or 18 bits in the critical frequency range 0-7 kHz as a result of the 96kHz shaper."
    Thanks to esldude finding this

    http://patentscope.wipo.int/search/e...PCTDescription
    Sounds like they used the Scientific Jargon Generator (patent applied for) for this.
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  2. #12
    Senior Member Archimago's Avatar
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    Quote Originally Posted by Wombat View Post
    @Archimago
    I did no indeep reading leave alone understanding of that patent so i may be wrong.
    A blind quote that may not describe how the realworld implementation works:
    " The listener with access to all 24 bits may use the decoder of figure 5B to enjoy full bandwidth lossless reproduction of the 13-bit signal at point "A", i.e. with a resolution of 17 or 18 bits in the critical frequency range 0-7 kHz as a result of the 96kHz shaper."
    Thanks to esldude finding this

    http://patentscope.wipo.int/search/e...PCTDescription
    Thanks for the link. I believe I linked to that patent but didn't click on the adjacent tab to see the detailed description!

    Interesting. Indeed, this implementation described looks like it only leaves the 13 MSB's untouched, and the 14-16th bits "lossy" in some form. Also, it looks like the intent is:

    "Thus, it is generally not possible to pack losslessly and with PCM compatibility a 16-bit 96kHz signal into a 16-bit 48kHz channel, and neither is it generally possible to pack losslessly and with PCM compatibility a 24-bit 96kHz signal into a 24-bit 48kHz channel. However, PCM-compatible lossless packing of a 16-bit 96kHz signal into a 24-bit 48kHz channel is usually feasible."

    and this:

    "The coefficients for Gerzon's 96kHz shaper, which provides nearly five bits of perceptual improvement, were given in Acoustic Renaissance for Audio, "A Proposal for High-Quality Application of High-Density CD Carriers" private publication (1995 April); reprinted in Stereophile (1995 Aug.); in Japanese in J. Japan Audio Soc, vol. 35 (1995 Oct.); available for download at www. meridian- audio.com/ara. Stuart provides a careful analysis considering the capabilities of human hearing ("Coding for High-Resolution Audio Systems" J. Audio Eng. Soc, Vol. 52, No. 3, 2004 March, see especially figure 16) from which one may conclude that a 44.1 kHz sampled digital system properly quantised with TPDF dither (but without noise shaping) to 20.5 bits will always provide sufficient dynamic range as a distribution medium. The non-noise-shaped noise spectral density is reduced by a further 3.4dB when 96kHz sampling is used. We can conclude that a 16-bit 96kHz channel with appropriate noise shaping is entirely adequate as a distribution format, meeting audiophile requirements with some margin to spare"

    Interesting, Meridian is indeed feeling that dithered & noise-shaped 16/96 is good enough for "audiophile requirements". The technique is more complicated than I envisioned. The technique can compress 16/96 into 24/48 "usually feasibly" in a "lossless" fashion in about 97% of those songs analyzed because it just so happens that there's not too much happening in the upper frequencies in most songs (no surprise!). Presumably then, if a piece of music had a lot of "detail" (strong dynamics?) above 24kHz, then this system would not be able to capture it all... Hmmm, this is certainly a different type of definition of "lossless" than what we're used to isn't it? Some kind of "limited" losslessness depending on how close the music conforms to expectations.

    It'll be good to see how this all works out!

    Of course, we don't even know for sure if this is exactly how MQA will be implemented. A bit disturbing that they're touching the last 3 bits so it doesn't even appear to be 16-bit perfect...
    Last edited by Archimago; 2015-01-16 at 18:26.
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  3. #13
    Senior Member Wombat's Avatar
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    This all comes down to the magic filter in action. They can remove lots of data but the superfilter applied makes is better sounding as the real full bit version.
    They prepared the world lately together with the AES with placing a paper about the audibility of filters. The word will spread. You know this one i guess.
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  4. #14
    Senior Member Archimago's Avatar
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    Quote Originally Posted by Wombat View Post
    This all comes down to the magic filter in action. They can remove lots of data but the superfilter applied makes is better sounding as the real full bit version.
    They prepared the world lately together with the AES with placing a paper about the audibility of filters. The word will spread. You know this one i guess.
    I'm thinking you mean this:
    The Audibility of Typical Digital Audio Filters in a High-Fidelity Playback System

    This paper describes listening tests investigating the audibility of various filters applied in high-resolution wideband digital playback systems. Discrimination between filtered and unfiltered signals was compared directly in the same subjects using a double-blind psychophysical test. Filter responses tested were representative of anti-alias filters used in A/D (analog-to-digital) converters or mastering processes. Further tests probed the audibility of 16-bit quantization with or without a rectangular dither. Results suggest that listeners are sensitive to the small signal alterations introduced by these filters and quantization. Two main conclusions are offered: first, there exist audible signals that cannot be encoded transparently by a standard CD; and second, an audio chain used for such experiments must be capable of high-fidelity reproduction.

    Authors: Jackson, Helen M.; Capp, Michael D.; Stuart, J. Robert
    Affiliation: Meridian Audio Ltd., Huntingdon, UK
    AES Convention:137 (October 2014) Paper Number:9174 Import into BibTeX
    Publication Date:October 8, 2014
    Subject:Perception: Part 2


    Indeed. It appears we need super filters :-)
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  5. #15
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    I wonder what 'signals' means ... do you know if they used music for these tests?
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  6. #16
    Senior Member Archimago's Avatar
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    Quote Originally Posted by darrenyeats View Post
    I wonder what 'signals' means ... do you know if they used music for these tests?
    No alas, I don't have access to the AES journal through my university library.

    Anyone around here in the audio engineering world?
    Archimago's Musings: (archimago.blogspot.com) A 'more objective' audiophile blog.

  7. #17
    Senior Member Wombat's Avatar
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    Don't worry to much about this paper. They proved that by 56% (slightly better as flipping a coin) on 45.000$ speakers with special treated silent room using SUB-standard filtering that lowpassed music can be discerned.
    The exact filters used with MatLab were not offered, leave alone the real music samples. It is known the filters are very steep and they used a rectangular dither method even the paper writers (Meridian) don't see as sufficient but use it for the test.
    Also i saw no clear description if the difference was found as really better sounding in any concrete way, only a difference.
    They used an ultra hard metal tweeter with their speakers that itself may cause IM in a way that may sound different lowpassed. No attempt was made to exclufde that.
    So it may just be the "Most comprehensive paper ever published about metal tweeter IM"
    It becomes even more funny when following their conclusion that it must be the way of the filter acting while they did not try anything to prove different filters sounding different. They more or less copied their Meridian marketing speech into the AES paper.
    A clever BUY-IN!
    Thats how i understand it after reading some discussions and snippets of the original paper i found online.

    I don't know anything about the signals they talk about.

    There is also a long thread at Hydrogen with lots of info.
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  8. #18
    Senior Member Archimago's Avatar
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    Quote Originally Posted by Wombat View Post
    Don't worry to much about this paper. They proved that by 56% (slightly better as flipping a coin) on 45.000$ speakers with special treated silent room using SUB-standard filtering that lowpassed music can be discerned.
    The exact filters used with MatLab were not offered, leave alone the real music samples. It is known the filters are very steep and they used a rectangular dither method even the paper writers (Meridian) don't see as sufficient but use it for the test.
    Also i saw no clear description if the difference was found as really better sounding in any concrete way, only a difference.
    They used an ultra hard metal tweeter with their speakers that itself may cause IM in a way that may sound different lowpassed. No attempt was made to exclufde that.
    So it may just be the "Most comprehensive paper ever published about metal tweeter IM"
    It becomes even more funny when following their conclusion that it must be the way of the filter acting while they did not try anything to prove different filters sounding different. They more or less copied their Meridian marketing speech into the AES paper.
    A clever BUY-IN!
    Thats how i understand it after reading some discussions and snippets of the original paper i found online.

    I don't know anything about the signals they talk about.

    There is also a long thread at Hydrogen with lots of info.
    Interesting. Thanks for the summary!

    I'm wondering, if you've ever attended these kinds of talks/presentations? I know that in my field, sometimes criticisms and arguments can get quite intense even in formal presentations when the results look questionable and the paper/research appears inadequate.
    Archimago's Musings: (archimago.blogspot.com) A 'more objective' audiophile blog.

  9. #19
    Senior Member Mnyb's Avatar
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    Quote Originally Posted by Wombat View Post
    Don't worry to much about this paper. They proved that by 56% (slightly better as flipping a coin) on 45.000$ speakers with special treated silent room using SUB-standard filtering that lowpassed music can be discerned.
    The exact filters used with MatLab were not offered, leave alone the real music samples. It is known the filters are very steep and they used a rectangular dither method even the paper writers (Meridian) don't see as sufficient but use it for the test.
    Also i saw no clear description if the difference was found as really better sounding in any concrete way, only a difference.
    They used an ultra hard metal tweeter with their speakers that itself may cause IM in a way that may sound different lowpassed. No attempt was made to exclufde that.
    So it may just be the "Most comprehensive paper ever published about metal tweeter IM"
    It becomes even more funny when following their conclusion that it must be the way of the filter acting while they did not try anything to prove different filters sounding different. They more or less copied their Meridian marketing speech into the AES paper.
    A clever BUY-IN!
    Thats how i understand it after reading some discussions and snippets of the original paper i found online.

    I don't know anything about the signals they talk about.

    There is also a long thread at Hydrogen with lots of info.
    Yes research are not incorruptible , that's what peer review are for .
    Seems like Meridian get tangled in some bias in thier research , the results seems weak ,but they want to believe in it . Especially when there is a bussiness opurtunity at stake .
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  10. #20
    Senior Member ralphpnj's Avatar
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    Quote Originally Posted by Mnyb View Post
    Yes research are not incorruptible , that's what peer review are for .
    Seems like Meridian get tangled in some bias in thier research , the results seems weak ,but they want to believe in it . Especially when there is a bussiness opurtunity at stake .
    Like any halfway decent detective story - follow the money, always follow the money.

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