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Nikhil
2005-07-20, 09:00
Hi all,

As I understand it, an HDCD stream is a standard 16 bit redbook CD-DA stream with additional data encoded into the 2 least significant bits. On playback through an HDCD decoder, the extra data is used to generate a 20 bit stream. Is it possible through software to convert an HDCD source into a 20 bit linear PCM file i.e. a 20 bit .wav or .flac file? I would like to generate a 20 bit LPCM stream that plays through my external DAC. I know that windows media player 9 and 10 are hdcd compatible. Is there any way to use that capability?

Thanks,

Nikhil

RmM
2005-08-17, 10:40
Hi. Yes, HDCD-compliant CDs store additional information encoded in the least significant bits. And when you make a bit-accurate rip, it will have this information included. So, it should be totally possible to decode a good lossless 16-bit HDCD rip into something better. However, HDCD is a proprietary method as far as I know, and now Microsoft owns the intellectual property. It might well be that a software-based HDCD decoder not licensed by M$ would be illegal in some countries, but it's definitely possible if a dapper coder would get ahold of the HDCD specs.

However, supposing that the resulting stream would be 20-bit, it's a very odd format, that isn't directly supported by most programs or soundcards - it would probably need to be converted into 24 bits or something... although that isn't a detrimental process with a good algorithm, and could easily be integrated in the software decoder itself.

I love the idea, myself.

John Stimson
2005-08-17, 15:46
I submitted a feature request for this at bugs.slimdevices.com a little while before the SB2 was released. Please go vote for this feature!

Nikhil
2006-08-02, 14:46
I was wondering what the status of this feature request was (see bug 1105). I know it's not really important, but it's been over a year since we last posted about HDCD, and I was just curious if it is even remotely on anyone's radar at the moment.

N

AnotherTribe
2006-08-02, 18:19
I too voted for this feature request. Like others, this is not a big deal but would certainly be the icing on my Squeezebox cake. I would really like to hear all my King Crimson remasters in their full HDCD glory! The thought of shelling out for a new HDCD amp or player for half a dozen or so CD's just does not make sense.

RalphO
2006-08-02, 18:26
This subject is something that I have been thinking about recently. The reason is that I opwn an Arcam CD player that has the capability of playing HDCD's. When a HDCD is playing in it an extra light comes on to indicate the 20 bit sampling. Unfortunately to date I have only found that I own less than 10 CD's that are HDCD.

The interesting thing for this thread is that I prefer to play my SB3 through the DAC of the Arcam. When I play a HDCD that I have ripped, the Arcam still detacts the 20 bit code and on comes the light. I really did not expect that a ripped CD through the SB3 would do this. Anyone else had this experience?

Nikhil
2006-08-02, 19:23
The interesting thing for this thread is that I prefer to play my SB3 through the DAC of the Arcam. When I play a HDCD that I have ripped, the Arcam still detacts the 20 bit code and on comes the light. I really did not expect that a ripped CD through the SB3 would do this. Anyone else had this experience?


The fact that the SB2/3 maintains HDCD information with lossless compressed or uncompressed HDCD rips (as long as the digital volume is kept at full) has been discussed on these forums before. I guess it is analogous to DTS or Dolby Digital pass through.

What is news to me is that the Arcam CD player can be used as an external DAC like some Wadia and Cary players. Do newer Arcam players still do HDCD decoding or have they discontinued this feature?

N

JohnSwenson
2006-08-02, 21:25
The problem is that Microsoft now owns the rights to HDCD and charges a humongous fee to license it. They seem to have setup their fee structure asuming its going to chip makers who would sell the decoding chips to many different companies rather than as a software decoder to one company.

If Slim Devices were to offer HDCD decoding as either part of a SB or even slimserver without obtaining the proper licensing from Microsoft I have little doubt they would be under immediate legal attack from MS.

Now the fun part is to try and figure out how to get at the 20 bits from media player. IF you can convince it to send out a 20 bit stream slimserver could be made to read it. I tried playing around with this a bit last year and could not find an easy way to get those 20 bits out of it. (Microsoft doesn't want to make it easy on anyboby) I'm sure there is a way to do it, but I didn't have enough time tospend on it.

John S.

Nikhil
2006-08-03, 05:16
Now the fun part is to try and figure out how to get at the 20 bits from media player. IF you can convince it to send out a 20 bit stream slimserver could be made to read it. I tried playing around with this a bit last year and could not find an easy way to get those 20 bits out of it. (Microsoft doesn't want to make it easy on anyboby) I'm sure there is a way to do it, but I didn't have enough time tospend on it.




Same here. Last year I spent quite some time trying to rip HDCDs using WMP 9 and 10, but I couldn't get it to export a 20 bit LPCM file even though I did stumble across some web page which says this is possible.

Has anyone used the digital output of a higher end (24 bit) audio card to feed an external HDCD compatible DAC? In such cases will the HDCD logo on the extrnal DAC light up along with the WMP HDCD logo, or is the HDCD information only processed when D/A conversion takes place within the computer?

You are right - it might be prohibitively expensive for SlimDevices to offer HDCD encoding within Slimserver or within the SqueezeBox hardware (though it might have been a possibility in the audiophile Transporter), however what if some hobbyist/enthusiast were to write a free plugin? Would that be a possibility?

N

TiredLegs
2006-08-03, 08:49
Has anyone used the digital output of a higher end (24 bit) audio card to feed an external HDCD compatible DAC? In such cases will the HDCD logo on the extrnal DAC light up along with the WMP HDCD logo, or is the HDCD information only processed when D/A conversion takes place within the computer?
If you rip your HDCDs to lossless files that produce data streams bit-for-bit identical to the original data, the digital output of a 16-bit audio card should be properly decoded by an external HDCD-compatible DAC. You don't need a 24-bit card, since the original data on the CD is only 16-bits (even though it can represent up to 20-bits of data through the HDCD dynamic range compression/expansion).

Nikhil
2006-08-03, 11:12
If you rip your HDCDs to lossless files that produce data streams bit-for-bit identical to the original data, the digital output of a 16-bit audio card should be properly decoded by an external HDCD-compatible DAC. You don't need a 24-bit card, since the original data on the CD is only 16-bits (even though it can represent up to 20-bits of data through the HDCD dynamic range compression/expansion).

I think you misunderstood my question. I am aware that ripping HDCDs to a lossless format, if done correctly, will preserve the HDCD information. What I was wondering was, if it is possible for windows media player to decode an HDCD stream and output it as a 20bit LPCM stream from the digital out of a higher end sound card.

N

TiredLegs
2006-08-03, 12:19
I think you misunderstood my question. I am aware that ripping HDCDs to a lossless format, if done correctly, will preserve the HDCD information. What I was wondering was, if it is possible for windows media player to decode an HDCD stream and output it as a 20bit LPCM stream from the digital out of a higher end sound card.
Now I see what you were getting at. But if you have an HDCD capable external DAC, why not just let the external DAC do the HDCD decoding rather than having Windows Media Player do it?

Nikhil
2006-08-03, 12:31
Now I see what you were getting at. But if you have an HDCD capable external DAC, why not just let the external DAC do the HDCD decoding rather than having Windows Media Player do it?

If I had an HDCD capable DAC.... but I don't ... so I was wondering if I could use WMP to generate 20-bit LPCM files that I could convert to FLAC and playback through my good (but non-HDCD decoding) DAC.

Olav Sunde
2006-08-03, 14:13
This link to an AudioAsylum thread describes a method for decoding HDCD
to LPCM http://db.audioasylum.com/cgi/t.mpl?f=dvda&m=20504

In combination with a plugin for SlimServer that could route the output
from a player like WMP or Foobar to SB as discussed in this thread
http://forums.slimdevices.com/showthread.php?t=20448 would be neat.

Olav

JohnSwenson wrote:
> The problem is that Microsoft now owns the rights to HDCD and charges a
> humongous fee to license it. They seem to have setup their fee
> structure asuming its going to chip makers who would sell the decoding
> chips to many different companies rather than as a software decoder to
> one company.
>
> If Slim Devices were to offer HDCD decoding as either part of a SB or
> even slimserver without obtaining the proper licensing from Microsoft I
> have little doubt they would be under immediate legal attack from MS.
>
> Now the fun part is to try and figure out how to get at the 20 bits
> from media player. IF you can convince it to send out a 20 bit stream
> slimserver could be made to read it. I tried playing around with this a
> bit last year and could not find an easy way to get those 20 bits out of
> it. (Microsoft doesn't want to make it easy on anyboby) I'm sure there
> is a way to do it, but I didn't have enough time tospend on it.
>
> John S.
>
>

Nikhil
2006-08-03, 16:18
This link to an AudioAsylum thread describes a method for decoding HDCD
to LPCM http://db.audioasylum.com/cgi/t.mpl?f=dvda&m=20504

Olav


Thank You !! This is what I was looking for.

RalphO
2006-08-03, 17:36
What is news to me is that the Arcam CD player can be used as an external DAC like some Wadia and Cary players. Do newer Arcam players still do HDCD decoding or have they discontinued this feature?

N[/QUOTE]

I cannot tell you whether any other Adcom CD players have this feature. The model I own is the Adcom GCD-750.

Another point is that I have never deliberately purchased a HDCD I have just found out certain CD's are encoded this way when I got them home. I also have not found the HDCD logo on thewse CD's. Maybe we should start a thread to help identify available HDCD's.

TiredLegs
2006-08-03, 18:06
If I had an HDCD capable DAC.... but I don't ...
Sorry, I thought that was what your earlier question was asking.

Has anyone used the digital output of a higher end (24 bit) audio card to feed an external HDCD compatible DAC?

Skunk
2006-08-03, 19:40
Maybe we should start a thread to help identify available HDCD's.

there's this database:
http://www.hifimusic.se/hdcd/index.php?p=base

guest
2006-08-28, 23:19
http://www.chronotron.com/content.php?page=downloads

waveout plugin suposedly captures the decoded bitstream from wmp

I've used it with a hdcd and wmp 10 on a ~ 8 mo old gateway under win xp home

it does create 44.1 24-bit wave files (winamp>file properties)

can't say I've found a easy way to inspect and verify dynamic range yet

blackbear
2006-08-29, 19:10
Here are links to the two HDCD related U.S. patents:

http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1&Sect2=HITOFF&p=1&u=%2Fnetahtml%2Fsearch-bool.html&r=1&f=G&l=50&d=PALL&RefSrch=yes&Query=PN%2F5479168
http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1&Sect2=HITOFF&p=1&u=%2Fnetahtml%2Fsearch-bool.html&r=1&f=G&l=50&d=PALL&RefSrch=yes&Query=PN%2F5872531

I wonder if these documents contain sufficient information for someone who wanted to implement, say, a HDCD decoding plug-in for Slimserver.

Nikhil
2007-02-07, 21:26
http://www.chronotron.com/content.php?page=downloads

waveout plugin suposedly captures the decoded bitstream from wmp

I've used it with a hdcd and wmp 10 on a ~ 8 mo old gateway under win xp home

it does create 44.1 24-bit wave files (winamp>file properties)

can't say I've found a easy way to inspect and verify dynamic range yet

Somebody seems to have compared the dynamic range between decoded and undecoded HDCDs

http://www.head-fi.org/forums/showthread.php?t=221104

Perhaps I will run some of my HDCDs through this wavout plugin prior to flac conversion, and see how they compare with normal EAC rips.

Nikhil