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Does EAC correctly rip HDCD encoding?

Discussion in 'Audio Hardware' started by LeeS, Apr 3, 2009.

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  1. LeeS

    LeeS Martini Time Thread Starter

    Location:
    Atlanta
    Just curious, I want to backup some HDCDs I have. Thanks. :righton:
     
  2. Dream Operator

    Dream Operator New Member

    Location:
    Lakewood, CO
    Hi Lee,

    EAC will rip the audio the same as it is on the CD, 16/44.1.

    Forum Member jojopuppy a little program to decode HDCD information from .wav files in a thread about the AF Schools Out.

    http://www.stevehoffman.tv/forums/showpost.php?p=4242630&postcount=308

    It processes the wave files and converts them to 24bit.

    I have used it myself, and the files do come out different, but I am not sure if it is the same as playing a CD through an HDCD decoder. Perhaps others can speak on that.

    Hope that is of some help,

    Tim
     
  3. LeeS

    LeeS Martini Time Thread Starter

    Location:
    Atlanta
    Very helpful. Thank you Tim.
     
  4. CardinalFang

    CardinalFang New Member

    Location:
    ....
    I've been using dbPoweramp for HDCD ripping. It saves the files as 24-bit WAV (or FLAC, Apple Lossless, etc). It supports Accurate Rip and will give you a log file.

    I wish EAC did this, but I find dbPoweramp to be a useful tool for conversions. With a hard drive full of FLACs, it saves a lot of time when I convert to Lame MP3 for the iPod.
     
  5. 3rd Uncle Bob

    3rd Uncle Bob Forum Resident

    I've ripped Neil Young's Greatest Hits & On the Beach and made a different Best Of comp using some of the later's tracks in place of ones I didn't care for on the GH. And it plays as HDCD encoded. But I didn't adjust any of the tracks' volume or EQ nor did any crossfading.
     
  6. CardinalFang

    CardinalFang New Member

    Location:
    ....
  7. GreenDrazi

    GreenDrazi Truth is beauty

    Location:
    Atlanta, GA
    Yes.

    EAC rips an HDCD encoded disc exactly they way it’s on the disc - IOW, bit perfect. Which means that the 16/44 PCM file has a HDCD flag and EAC accurately reproduces that flag in the ripped wav file. It does not, however, decode the HDCD file. The tag also survives if you compress it to flac and decompress back to wav. If you mount the ripped wav file as a virtual image and play it back in Windows Media Player, it recognizes the HDCD encoding.

    You can use the command line HDCD.exe program to decode the ripped wav file to 24bit. This program is also found as a DSP plugin in dbpoweramp.

    To keep my rips as accurate as possible even for HDCD discs, but I want then decoded, I use EAC to rip and then use dbpoweramp to decode it to 24 bit. I usually load the decompressed wav files into a wav editing program and raise the volume level if needed.
     
  8. wrat

    wrat Forum Resident

    Location:
    S.Fla
    another yes here I use EAC to rip to flac then use media monkey to output bit perfect to my Audio Alchemy dac and the HDCD light comes on when it is supposed to
     
  9. LeeS

    LeeS Martini Time Thread Starter

    Location:
    Atlanta
    So just to be clear, if I rip an HDCD encoded CD via EAC then write the file to a blank CDR, then that CDR will play back exactly the same as the HDCD original CD?
     
  10. OcdMan

    OcdMan Forum Resident

    Location:
    Maryland
    Yes. Just don't do any volume changes or anything else to it.
     
  11. jojopuppyfish

    jojopuppyfish Senior Member

    Location:
    Maryland
    BTW, hdcd.exe was written by a guy named Christopher Key.

    Looks like they are keeping current versions here:
    http://www.srcf.ucam.org/~cjk32/hdcd/
    This is the thread that started the creation of this project:
    http://forum.doom9.org/showthread.php?t=129136

    BTW, if you type hdcd.exe -?, you'll get a list of arguments.
     
  12. GreenDrazi

    GreenDrazi Truth is beauty

    Location:
    Atlanta, GA
    Yep! :wave:

    But please, give it a try yourself.
     
  13. emmodad

    emmodad Forum Resident

    Location:
    bay area, ca

    a few comments (caveat: i'm rather ill, so not really together to post lots o detail. pls feel free to search previous posts (key on HDCD emmodad) here at SHF and on head-fi; somewhere in there are links to the original AES paper on HDCD by Keith Johnson and Pflash Pflaumer if you want gorey details -- 1996 AES Los Angeles convention presentation "Compatible Resolution Enhancement in Digital Audio Systems."):


    1/ jojopuppy's clever technique apparently makes use of hdcd.exe


    2/ pls note (this is not directed at jojopuppy, but is simply a general comment about hdcd.exe) that unless there has been a huge recent change, hdcd.exe does not perform full HDCD decoding.

    hdcd.exe recognizes presence of HDCD control packets and performs decoding of only the HDCD encode amplitude resolution processing functions (ie, if used by the mastering engineer, the reversable soft peak limiting aka "peak extend" and low-level expansion). it does not provide dynamic switching of conjugate reconstruction filters, which is where you get a primary element of the sonic benefit from HDCD.

    i do not use, nor have i explored dbpoweramp. however IIRC there is the same issue, unless the makers of dbpoweramp have an HDCD license and permission to use the sets of filter coefficients. (this is not something "easily" reverse-engineered). thought i read somewhere that the dbpoweramp HDCD capability is simply a plugin for hdcd.exe?


    3/ further on what posters have referred to as EAC preserving the "flag": HDCD processing embeds control signal information in the audio data on an as-needed basis. this information concerns parameters and commands about dynamic changes in HDCD encoder algorithms and functions, to be read and acted upon by an HDCD decoder.

    it does this by "stealing" the audio data LSB for a very small percentage of the time, IIRC typically about 2% of audio, and inserting the information as pseudo-random noise-encrypted control signals (a command stream) within the dithering function. it's simply packets of command data which the decoder can detect and extract. extracting this hidden code from the LSBs is the first decoder operation (aka "recognizing the flag")

    as long as the 16/44.1 audio data is faithfully preserved when extracted from CD, this "hidden code" embedded across the audio LSBs is preserved and HDCD decode will happen correctly. so, if audio data is ripped bit-perfect and is not processed (ie no gain, EQ, dynamics, whatever which could modify the data value and hence change the LSBs), the ripped fileset can be burned to a CD, or stored on a server, or whatever. good if you want to rip to storage and then feed via server to playback hardware which can perform HDCD decode on an incoming datastream.

    BTW, it's this issue concerning preservation of the HDCD "flag" which allows people to say "if HDCD is preserved then your data is transferred bit-perfectly"; this is what Reference Recordings does with the new HRx (HDCD "flag" in 24th bit, but there is no HDCD "processing" on the data according to RR). if the flag is maintained, the data has not been changed between delivery medium (HRx DVD) and the decoder (ie input to a Berkeley alpha DAC).

    and for those who moan that Microsoft doesn't maintain HDCD audio capability (it's going or gone from recent versions of WMA): their interest in acquiring the HDCD patents appears primarily to have been for leverage of this embedded hidden subcode capability to use in "watermarking" software distributions, to protect against code changes or modifications.

    hope that was slightly interesting for y'all.
     
    wilejoe likes this.
  14. apileocole

    apileocole Lush Life Gort

    Very interesting. Thank you for taking the effort to comment and I hope you will be feeling better asap.

    Not surprised re: Microsoft. Would that there was an EAC for Linux. Still I'm glad to know the HDCD format can be backed up and/or used in file form provided the data maintains full integrity.
     
  15. ironluke

    ironluke Member

    Location:
    Zena, Italy
    EAC works perfectly on Linux under Wine.

    Luca
     
    ThirdBowl likes this.
  16. Leigh

    Leigh http://orf.media

    cdparanoia has been around for about 15 years - long before EAC came around. It's what I've used since the early days of CDR trading in the live music circles, and it works great. The CDROM drives 15 years ago did not do DAE very well at all but cdparanoia would get it right.

    Since HDCD is encoded in the least significant bit in the 16 bit data, it is preserved when extracted with cdparanoia. As I understand it, burning a CDR from the WAV files from a HDCD ripped source should preserve the HDCD as a HDCD player will sense the signal in the LSB.
     
  17. CardinalFang

    CardinalFang New Member

    Location:
    ....
    Yes, thanks for posting. I didn't realize that MS acquired the HDCD patents.

    So I suppose the best thing I can do is use EAC for my HDCDs, and hope that somebody reverse engineers the HDCD decoding. It would be nice if software media players would be able to decode that data... or for a Squeezebox to decode it.

    It sounds as though there's not much to be gained from using HDCD.exe or dbPoweramp.
     
  18. hvbias

    hvbias Midrange magic

    Location:
    Northeast
    Microsoft bought out the HDCD rights from Pacific Microsystems.

    WMP11 can playback HDCD content (older versions might be able to as well, but I have never tried).
     
  19. Dream Operator

    Dream Operator New Member

    Location:
    Lakewood, CO
    Thanks jojopuppyfish. Sorry I messed up your name!

    Thanks emmodad, that was very informative. I knew there was more to it. Get well soon!

    Tim
     
  20. jojopuppyfish

    jojopuppyfish Senior Member

    Location:
    Maryland
    Bottom line, using hdcd.exe (Which is the algorithm used in EAC and Dbpoweramp) does make the output files sound a lot better.....
    You'll have to do your own due diligence to determine if you agree with me.
     
  21. Metralla

    Metralla Joined Jan 13, 2002

    Location:
    San Jose, CA
    Also thanks here to emmodad.
     
  22. LeeS

    LeeS Martini Time Thread Starter

    Location:
    Atlanta
    Yes, very smart reply. Thank you. :righton:
     
  23. Metoo

    Metoo Forum Hall Of Fame

    Location:
    Spain (EU)
    Yes, but can it decode it? I see no mention of HDCD on any menu or sign that it is decoding it anywhere, as used to be the case with a previous version.
     
  24. Metoo

    Metoo Forum Hall Of Fame

    Location:
    Spain (EU)
    Thanks Emmodad for your post, very interesting.

    Get well soon. :)
     
  25. hvbias

    hvbias Midrange magic

    Location:
    Northeast
    Yes it can decode as well.
     
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