HDCD

[jadded]

I have a lot of HDCD CDs ripped to itunes (AIFF). I'm looking for a relatively simple way to decode these tracks for playback. Assuming all 20 bits are intact in itunes and the Mac is connected via USB to the new Oppo BDP-95 (which can decode HDCD disks), will the Oppo decode the HDCD content?

 

[juliocat]

I don't have an Oppo but i don't think the Mac can be connected to the Oppo via USB, you can use an external USB disk but not the mac, try with the network connection or wifi.

 

The oppo can't decode AIFF files so you will need to convert these files to FLAC or WAV format, the HDCD code will remain intact with any of these formats and the Oppo will decode it properly.

 

[jadded]

Thanks for the reply. If both the mac and the oppo have USB connections, why can't they be connected that way?

 

[juliocat]

The Oppo BDP-95 manual:

 

This unit supports “USB Mass Storage Class Bulk-Only Transport” devices only. Most USB thumbs drives, portable hard disk drives and card readers conform to this device class.

 

The Mac is not a “USB Mass Storage Class Bulk-Only Transport” device, but you can share a folder with your music, photos and movies and play them in the oppo via the network connection, the oppo manual have good examples.

 

http://download.oppodigital.com/BDP95/BDP-95_English_Manual_v1.5.pdf

 

 

[bleedink]

You have to decode the hdcd info into the file before it reaches the oppo or it won't play as 20 bit. Use dbpoweramp music converter and the hdcd plug in to get a file that plays properly or you need to convert to cd again and play the disc.

 

[juliocat]

The Oppo can decode HDCD so is not necessary to convert, just send the flac or wav file as is.

 

[bleedink]

I'd never seen the light go on unless I am playing a disc. The same light will go on if it senses for instance DTS in the flac, or DTS-HD MSTR for that matter. Perhaps I missed something. The conversions of flacs I've done with the hdcd tool seem to sound better but perhaps this doesn't work over DLNA? Or am I getting the placebo effect? When I reconstitute the disc I get the same SQ as the files I've converted and the light goes on. The indicator for hdcd works when you play wavs and such? I personally noticed a huge difference with Stevie Wonders Talking Book.

 

[The Computer Audiophile]

HDCDs should be ripped like all other Redbook CDs. Using an HDCD capable DAC with any input such as AES, S/PDIF, Ethernet UPnP/DLNA will not matter. As long as the data is bit perfect the HDCD light should illuminate.

 

 

 

[6th.replicant]

Chris: "HDCDs should be ripped like all other Redbook CDs."

 

Forgive my ignorance, but is it possible to rip an HDCD to iTunes (using OS X 10.6.8) as 20-bit? (When I rip HDCDs to iTunes, 'Get Info' states that the files are 16-bit.)

 

Thanks.

 

[juliocat]

Itunes an any player in the mac can't decode HDCD. Microsoft Fault.

 

[The Computer Audiophile]

HDCDs are 16 bit. Period. Software on a computer that outputs digital data does not have to decode HDCD. Thus, ripping HDCDs in iTunes at 16 bit like a standard Redbook CD and playing this rip back via any bit perfect software will output the HDCD information identical to the CD. I do this on a daily basis. For example, when I rip a Reference Recordings CD that is HDCD using iTunes I can play it back in iTunes and illuminate the HDCD indicator on my Berkeley Audio Design Alpha DAC.

 

Rip as normal. Play as normal. HDCD will work perfect.

 

 

 

[jadded]

Thanks Chris and all. So, it sounds like all I need is a DAC which can decode HDCD and connect to a Mac. The Berkeley Audio Design Alpha DAC sounds wonderful but I would be hard pressed to drop that kind of coin on any single audio component. I was hoping to find something simple and economical like the Halide HD DAC that could decode HDCD. Do you know of anything like that?

 

At $1K, even though I have little use for any of the video or home theater capability of the highly recommended Oppo BDP-95, it peaked my interest because it appears it could decode itunes ripped HDCD files via USB or wifi. Is this true? I have trouble believing the wifi route would preserve the same fidelity as a wired connection, but what do I know? Even if this is possible, isn't there a more simple solution? A plug and play device like the Halide that preserves the sound, handles HDCD and costs less than $2K? Or a Peachtree (i)Nova that has HDCD capability?

 

[ericuco]

You might consider using dBpoweramp to rip HDCDs. As part of the DSP options, it will check CDs to see if there is any HDCD information on the CD and if detected, it will rip the CD as 24/44.1 format instead of Redbook format of 16/44.1. dBpoweramp will notify you after the rip if it found HDCD files. Not sure what is happening but my guess it that it is decoding(?) the HDCD information which according to Wikapedia:

 

"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.[2][3]

 

HDCD encoding places a control signal in the least-significant bit of a small subset of the 16-bit Red Book audio samples (a technique known as in-band signaling). The HDCD decoder in the consumer's CD / DVD player, or in some cases audio receiver, if present, responds to the signal. If no decoder is present, the disc will be played as a regular CD."

 

One other point is that there are a number of CDs out there that have HDCD information on the CD but it not advertised on the CD or sleeve. For instance, Lucinda Williams' "Car on a Gravel Road" and "World Without Tears" CDs both appear to be HDCD. I say appear because I have heard that some CDs have been "extended" and are not actual HDCD material. From what I have read, both of Lucinda Williams CDs are in fact HDCD.

 

So you might to check, some of your Redbook CDs to see if HDCD is available. Here is a listing of (potential) HDCDs:

 

http://www.head-fi.org/t/65414/hdcd-list

 

[Geickel]

HDCDs are 16 bit. Period. Software on a computer that outputs digital data does not have to decode HDCD. Thus, ripping HDCDs in iTunes at 16 bit like a standard Redbook CD and playing this rip back via any bit perfect software will output the HDCD information identical to the CD. I do this on a daily basis. For example, when I rip a Reference Recordings CD that is HDCD using iTunes I can play it back in iTunes and illuminate the HDCD indicator on my Berkeley Audio Design Alpha DAC.

 

Rip as normal. Play as normal. HDCD will work perfect.

 

Hey Chris,

My HDCD light doesn't light up when playing HDCD encoded files from USB on my BDP-95. Any suggestions?

[Miska]

Rip as normal. Play as normal. HDCD will work perfect.

 

Only if your DAC is then able to decode HDCD. Majority of DACs won't decode HDCD, so to get the advantage of the HDCD, it is better to decode it already at ripping time and any 24-bit capable DAC will benefit from it...

 

Especially the ripped content becomes more future proof, as I have serious doubts how many new HDCD-capable DACs there will be.

[accwai]

[...] My HDCD light doesn't light up when playing HDCD encoded files from USB on my BDP-95. Any suggestions?

 

Play the original disc that your rip comes from and you'll see the light coming on. The Oppo is probably checking for HDCD stream from CD only. From USB and DLNA, the light doesn't come on, but what is passed out through S/PDIF and Toslink is indeed HDCD. If you have a HDCD capable DAC behind the Oppo, the indicator on the DAC would come on.

 

Now in theory, all the necessary building blocks for handling HDCD from USB should be inside the Oppo already. So perhaps you can contact Oppo and inquiry about it.

 

Only if your DAC is then able to decode HDCD. Majority of DACs won't decode HDCD, so to get the advantage of the HDCD, it is better to decode it already at ripping time and any 24-bit capable DAC will benefit from it...

 

That assume there is one single officially correct way of mapping HDCD stream into hirez. Does anybody know if this is true?

 

Andy

[Miska]

That assume there is one single officially correct way of mapping HDCD stream into hirez.

 

Based on the limited information I've found about it, there's only single correct way to decode it. Just peak extension and low-level dynamic extension based on LSB-encoded data. AFAIK, these could be done using lookup-tables.

[The Computer Audiophile]

I believe there is filtering done at the DAC, assuming it has an HDCD decoder, based on receiving an HDCD encoded stream. A non-HDCD capable DAC won't benefit from a decoded rip at 24 bit because there is no software / hardware combination for decoding and processing.

 

I may be incorrect but this is what I believe.

[Miska]

A non-HDCD capable DAC won't benefit from a decoded rip at 24 bit because there is no software / hardware combination for decoding and processing.

 

Why not? All the things that would be performed by the PMD-100 digital filter chip are instead performed by the software decoder. It is all just DSP stuff.

 

Looking at the PMD-100 datasheet, it is connected to any standard DAC chip and there's nothing special beyond it's I2S output. It is similar digital filter like for example Burr-Brown DF1706 and the likes. It just has that "HDCD" decode processing when it detects the output and has one output pin to drive the indicator led. DAC connected to it's output doesn't know about it. The datasheet has example connection diagrams for three DAC chips that were popular at the time. It has dithered digital volume control and output bit depths of 16, 18, 20 and 24 bits.

 

The datasheet says:

"Data encoded with HDCD process information carries precisely encrypted signals, hidden within the LSB of the 16-bit data word. Over time, only 1 to 5% of the LSB is used for this hidden code. The encoded information is inaudible and causes no perceptible loss of information. The PMD-100 recognizes the encrypted signals as HDCD process information, and directs the decoding function to precisely reconstruct the high resolution signal in a form appropriate for output to the D-A converter being used."

 

Practically it seems to encode in LSB the current dynamic range so the signal can be transformed accordingly. So when the level is quiet the data is shifted downwards and when it is really loud, the clipped peaks can be extended. Thus the 16-bit input can be expanded to cover 20-bit range. And when played on normal CD player it just sounds a bit more compressed.

 

Here's for example some story about it:

The HDCD Enigma