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Thread: Hdcd dsp

  1. #16
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    Re: Hdcd dsp

    Quote Originally Posted by garym View Post
    no clue what happened there. I don't use HDCD DSP, even on my HDCDs (because I want a bit perfect rip, and ripping via the DSP you no longer have a bit perfect rip). I could later convert my rips to other versions using the HDCD DSP, but I've found it is rarely worth it because many HDCDs don't actually use the HDCD features that make a difference (e.g, Peak Extension).
    Thanks

  2. #17
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    Re: Hdcd dsp

    To repeat from a post I made on this forum four years ago, one reason you see "non-HDCD" HDCD encoded CDs is that some recording engineers and producers like the "sound" of the encoder/analog to digital converter, originally made by Pacific Microsonics, so they feed audio through it even though they have turned off many of the encoder HDCD "features".

    To quote from the HDCD WIKI regarding compatible playback" "HDCD encodes the equivalent of 20 bits worth of data in a 16-bit digital audio signal by using custom dithering, audio filters, and some reversible amplitude and gain encoding: Peak Extend, which is a reversible soft limiter; and Low Level Range Extend, which is a reversible gain on low-level signals. There is thus a benefit at the expense of a very minor increase in noise.[3]

    The claim that the encoding process is compatible with ordinary CD players (without audible distortion) is disputed: not being able to decode the peak soft limiting, a normal CD player will output distorted peaks.[4] "

    You might find the Hydrogen Audio WIKI on HDCD of some interest - https://wiki.hydrogenaud.io/index.ph...atible_Digital

    If the Wikipedia WIKI is correct about peak distortion (and I have no way to prove or disprove it), and your player does not have the built in decoder, you might find it desirable to use the decoder DSP built into dBpoweramp, but realize that the audio file can no longer be made into a bit perfect copy of the source CD. If you care about bit perfect rips, then you could keep two copies, the original bit perfect rip, and the decoded version to listen to, subsequently processed through the dBpa converter using the DSP decoder codec.

  3. #18
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    Re: Hdcd dsp

    Quote Originally Posted by schmidj View Post
    To repeat from a post I made on this forum four years ago, one reason you see "non-HDCD" HDCD encoded CDs is that some recording engineers and producers like the "sound" of the encoder/analog to digital converter, originally made by Pacific Microsonics, so they feed audio through it even though they have turned off many of the encoder HDCD "features".

    To quote from the HDCD WIKI regarding compatible playback" "HDCD encodes the equivalent of 20 bits worth of data in a 16-bit digital audio signal by using custom dithering, audio filters, and some reversible amplitude and gain encoding: Peak Extend, which is a reversible soft limiter; and Low Level Range Extend, which is a reversible gain on low-level signals. There is thus a benefit at the expense of a very minor increase in noise.[3]

    The claim that the encoding process is compatible with ordinary CD players (without audible distortion) is disputed: not being able to decode the peak soft limiting, a normal CD player will output distorted peaks.[4] "

    You might find the Hydrogen Audio WIKI on HDCD of some interest - https://wiki.hydrogenaud.io/index.ph...atible_Digital

    If the Wikipedia WIKI is correct about peak distortion (and I have no way to prove or disprove it), and your player does not have the built in decoder, you might find it desirable to use the decoder DSP built into dBpoweramp, but realize that the audio file can no longer be made into a bit perfect copy of the source CD. If you care about bit perfect rips, then you could keep two copies, the original bit perfect rip, and the decoded version to listen to, subsequently processed through the dBpa converter using the DSP decoder codec.

    Thanks for the info. Will look into it.

  4. #19
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    Re: Hdcd dsp

    I think I have found the answer to why it decoded the SACD to 24-bit. That particular Dire Straits SACD is also HDCD encoded, although it is not mentioned as such. It is there in the wiki link mentioned above, if you click further on the link of HDCD encoded CD

  5. #20
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    Re: Hdcd dsp

    Quote Originally Posted by Partha View Post
    I think I have found the answer to why it decoded the SACD to 24-bit. That particular Dire Straits SACD is also HDCD encoded, although it is not mentioned as such. It is there in the wiki link mentioned above, if you click further on the link of HDCD encoded CD
    But to be clear, dbpa did NOT decode the SACD to 24 bit. dbpa did not extract the SACD layer. It decoded the regular CD layer (that is also contained on the SACD physical disk) to HDCD. This "CD layer" could certainly be one created with HDCD, as you note.

  6. #21
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    Re: Hdcd dsp

    Quote Originally Posted by garym View Post
    But to be clear, dbpa did NOT decode the SACD to 24 bit. dbpa did not extract the SACD layer. It decoded the regular CD layer (that is also contained on the SACD physical disk) to HDCD. This "CD layer" could certainly be one created with HDCD, as you note.
    Yes, the CD layer is created with HDCD. Check the wikipedia link above.

  7. #22

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    Re: Hdcd dsp

    Quote Originally Posted by garym View Post
    Unlikely as one would have to have an old sony playstation with correct firmware to even try to do it. The makers of SACD disks do NOT want them ripped.
    One can now rip SACDs for your own backup using certain model players. I have an Oppo BDP 105D that can do so. There are others also. See this thread: https://audiophilestyle.com/forums/t...comment-559449. Start from the top...there are a couple of summaries on steps to follow and players that have the right combination of chip and firmware. Good luck.

  8. #23
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    Re: Hdcd dsp

    Nevertheless this is not legal in most countries...


    Dat Ei

  9. #24
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    Re: Hdcd dsp

    Quote Originally Posted by garym View Post
    I don't use HDCD DSP, even on my HDCDs (because I want a bit perfect rip, and ripping via the DSP you no longer have a bit perfect rip).
    Hello Garym. So far I have only enabled the HDCD DSP when I've been ripping discs which I know are HDCD encoded. That is, I deselect the HDCD DSP function when I'm ripping regular CDs, which make up the majority of my collection (although I understand that it makes no difference whether or not I leave the DSP HDCD function selected for these CDs, too).

    Anyway, after reading your comment, I'm now wondering whether I should re-rip the few HDCD discs that do I have without the HDCD DSP encoding. However, I don't understand why the option to rip HDCD to 20-bit exists if it results in an inferior copy to the standard 16-bit. Perhaps I'm missing something. Could you please explain a bit (no pun intended) more? Thanks.

  10. #25
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    Re: Hdcd dsp

    Quote Originally Posted by Supernaut View Post
    I'm now wondering whether I should re-rip the few HDCD discs that do I have without the HDCD DSP encoding. However, I don't understand why the option to rip HDCD to 20-bit exists if it results in an inferior copy to the standard 16-bit.
    What is your audio player?

  11. #26
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    Re: Hdcd dsp

    Quote Originally Posted by Supernaut View Post
    Hello Garym. So far I have only enabled the HDCD DSP when I've been ripping discs which I know are HDCD encoded. That is, I deselect the HDCD DSP function when I'm ripping regular CDs, which make up the majority of my collection (although I understand that it makes no difference whether or not I leave the DSP HDCD function selected for these CDs, too).

    Anyway, after reading your comment, I'm now wondering whether I should re-rip the few HDCD discs that do I have without the HDCD DSP encoding. However, I don't understand why the option to rip HDCD to 20-bit exists if it results in an inferior copy to the standard 16-bit. Perhaps I'm missing something. Could you please explain a bit (no pun intended) more? Thanks.
    it's not necessarily inferior. It's just not bit perfect copy of the CD. The use of the DSP to create a 24 bit depth (capturing the HDCD's 20 bit) etc. is a way of reverse engineering to get the same or similar benefits of playing the CD through an HDCD capable CD player. Such a process *may* actually sound better. If I wanted these 24 (20) bit depth files, I'd personally rip without the HDCD DSP to obtain bitperfect rip. Next, I'd create a new copy using dbpa converter of these files USING the HDCD DSP. Then my second copy would capture any benefit of the HDCD effect. I've done this a bit, but the difference wasn't worth it (for me). Keep in mind that many HDCD CDs don't actually use the aspects of HDCD that make any of this necessary (e.g. peak extension). For example, Grateful Dead releases are HDCD, but it has been a long while since any of these contained peak extension. Thus special handling is not needed.

  12. #27
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    Re: Hdcd dsp

    Quote Originally Posted by mville View Post
    What is your audio player?
    USB Audio Player PRO, which displays the 20 bit HDCD albums as being Hi-Res.

    Quote Originally Posted by garym View Post
    it's not necessarily inferior. It's just not bit perfect copy of the CD. The use of the DSP to create a 24 bit depth (capturing the HDCD's 20 bit) etc. is a way of reverse engineering to get the same or similar benefits of playing the CD through an HDCD capable CD player. Such a process *may* actually sound better. If I wanted these 24 (20) bit depth files, I'd personally rip without the HDCD DSP to obtain bitperfect rip. Next, I'd create a new copy using dbpa converter of these files USING the HDCD DSP. Then my second copy would capture any benefit of the HDCD effect. I've done this a bit, but the difference wasn't worth it (for me). Keep in mind that many HDCD CDs don't actually use the aspects of HDCD that make any of this necessary (e.g. peak extension). For example, Grateful Dead releases are HDCD, but it has been a long while since any of these contained peak extension. Thus special handling is not needed.
    Thank you, garym. I'm not sure I fully understand why the HDCD rip would not be bit perfect, but it doesn't matter. As I only have a handful of HDCD discs I'll just leave them the with the HDCD DSP in place. If I change my mind in the future I can quickly copy them again as 16 bit.

  13. #28
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    Re: Hdcd dsp

    Quote Originally Posted by Supernaut View Post
    Thank you, garym. I'm not sure I fully understand why the HDCD rip would not be bit perfect
    Because the HDCD DSP is upconverting the 16/44.1 file to 24/44.1. (this is why your player thinks the file is hi-res--that is, the 24 bit depth vs 16 bit depth)

  14. #29
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    Re: Hdcd dsp

    Quote Originally Posted by garym View Post
    Because the HDCD DSP is upconverting the 16/44.1 file to 24/44.1. (this is why your player thinks the file is hi-res--that is, the 24 bit depth vs 16 bit depth)
    So there isnít really anything special about the data on an HDCD disc, the HDCD coding just allows the data to be upsampled from 16 bit to 20/24 bit (which isnít possible with standard CDs). Is this correct?

  15. #30
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    Re: Hdcd dsp

    Quote Originally Posted by Supernaut View Post
    So there isn&*8217;t really anything special about the data on an HDCD disc, the HDCD coding just allows the data to be upsampled from 16 bit to 20/24 bit (which isn&*8217;t possible with standard CDs). Is this correct?
    Sort of correct. Yes, the data on the cd is 16/44.1. But buried in this data is some sort of indicators/flags, etc. regarding a few features (e.g., peak extension) that an HDCD capable CD player picks up on and uses during playback. The HDCD DSP in dbpa and the HDCD playback component in foobar2000 player are simply "reverse engineering" to get something close to what the HDCD capable player would use when playing.. And to do this the file has to be upconverted.

    If it makes you feel any better, I have many hundreds of HDCD CDs and I don't bother with anything special about any of them. I simply rip as 16/44.1 and play them on my system. I really wish manufacturers would drop HDCD. In effect, most have, although they still call things HDCD, they don't use any of the features that HDCD decoding would matter (e.g., like Peak Extension). As I mentioned, all the Grateful Dead HDCD CDs in recent years don't have PE feature, thus HDCD decoding would have essentially zero effect.

    See:
    https://en.wikipedia.org/wiki/High_D...atible_Digital
    "HDCD encodes the equivalent of 20 bits worth of data in a 16-bit digital audio signal by using custom dithering, audio filters, and some reversible amplitude and gain encoding: Peak Extend, which is a reversible soft limiter; and Low Level Range Extend, which is a reversible gain on low-level signals."
    Last edited by garym; 07-28-2021 at 07:20 AM.

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