HDCD: an investigation

By the way, I also compared just digitizing the analog output of an HDCD player, to the digital capture method -- the resulting waveforms are essentially the same. The 'analog out' method has to be done in real time, but anyone with an HDCD player and a 24-bit soundcard can that has line in, can do it, then compress the results to flac. The results will be as good as a digital rip, assuming your recording software and soundcard are good.

(But the WMP plugin method is a lot faster!)

 

Is anyone reading my first post, or are they just looking at the pretty waveforms?

"At the turn of the millennium HDCD was touted as a multi-benefit audio technology -- not only was the A/D and D/A filtering supposed to be top-flight, but it also offered what might be called 'virtual 20 bit' playback of 16-bit CDs."

HDCD supposedly offered at least two benefits....expanded dynamic range, and better conversion between analog and digital.

 

And to be clear, to decode the CD, you do have to enable WMP 24-bit decoding -- it's deep in the Options-->Devices-->Speakers-->Properties menu of WMP.

 

Have you made that available? It would be a very cool app to have for those of us whith large lossless libraries.

I'll be comparing spectral characteristics of decoded versus nondecoded versions soon...might be interesting. For what it's worth, when I did digital capture of analog HDCD out, I did use 88.2 or 96 Khz sampling, as per the Hydrogenaudio threads.

 

So when an HDCD-capable player (Oppo 970 for example) sends HDCD out the S/PDIF, it's 44/16 with the HDCD encoding, right?

 

Yes, digital out from hardware players is still undecoded. You have to have a downstream HDCD chip somewhere to decode it.

 

There's an interesting mention of HDCD mastering options (not sure how technically accurate it i) in this 'self-intervew' on Positive Feedback...including discussion of use of the 'HDCD box' simply for dithering high-bit digital input down to 16 bits for CD production.

http://www.positive-feedback.com/pfbackissues/0801/johnmarks.pf.interview.8n1.html

 

Thanks for that link! I have scoured the 'net for lists of HDCD releases and encountered some discussion forums that list those "turns the HDCD light on but not listed as HDCD-encoded" titles.

That link certainly clarifies some things.

 

Interesting thread, SiriusB

Anyone know if the Beach Boys Pet Sounds box or the 2001 remasters used peak extention?

If so I'll have to get ripping with WMP!

 

Here's a waveform of the 16-bit rip of "Blue Rondo a La Turk" from the HDCD remaster of "Time Out" followed by the 20-bit extraction.

 

From the looks of them, I'm gonna guess those are the same, in terms of dynamic range, with one just being several dB lower in peak level. Try running some stats on both to see.

(So far I've never seen a waveform with 'flattops' , like the one at top in your post, 'recover' its peaks, after decoding. I still see them in your lower waveform, eg between 4:20 and 4:40)

 

I'm also trying to determine how error-free WMP 'rips' are , when using the Chrono WAV plugin -- I highly doubt there's any error correction, though unless one's discs are damaged this shouldn't be much of an issue.

 

Have you tried/know anything about this tool? http://forum.doom9.org/showthread.php?t=129136

Could it be exactly what we're looking for?

 

Didn't work for me when I tried it - just went to a flashing cursor ad infinitum.

Should it take ages?

 

I rip an HDCD-encoded disc normally with EAC to a cue/wav image, then load that in Daemon Tools, which creates a fake CD drive that can load this and various other image formats and cause Windows to treat them as real discs. Convenient that the HDCD encoding is stored in-band, so it survives in whatever lossless format I decide to store it in...

 

Hm, it works for me and says "Detected HDCD" if it was a HDCD wav. I have only couple of HDCD wav rips and I don't know what effects they use, but at least the result is 24/44.1 wav.

 

I haven't tried it. I think you need to go into dos and type: hdcd.exe < 16bit.wav > 24bit.wav

"16bit.wav" would be whatever the original file is called. At least, I think.

 

Right - tried that and just got a flashing cursor like nothing much was happening

Actually, maybe the filename had spaces in which would have freaked out the code (damn that command line). I'll try again later.......

 

The doom forum command line tool works, and its output is identical (nulls out) to the WMP pluing's output -- *if* you trim them! That's a bit odd; the doom hdcd.exe tool seems to grab a few milliseconds more samples at the end, while the WMP tool seems to have added a few milliseconds of silence at the beginning. I'm curious to know if this happens for anyone else.
Either way, it seems hdcd.exe is a good tool, even better if it can be run in batch mode.

The Daemon Tools kludge is an excellent idea; I have that app and it vaguely occured to me that it might be useful for getting around WMPs 'CD input only' requirement for HDCD decoding. Now, if there's a flac plugin for WMP, that would be dandy....ah, here it is

http://www.losslessaudioblog.com/?p=40


I'm assuming neither tool involves sampling, since the output is 44.1, and from what I've read so far, to 'properly' sample decoded HDCD, 88.1 or higher is recommended....

 

It's good to know that the command line tool works - also surprising that someone actually cracked the hdcd code. Should we be surprised that wmp is outputting 44.1?

 

So, I presume what you'd do is rip an HDCD to a .wav image with EAC (high security mode), mount the cue, then play the 'disc' with WMP, capture the decoded output to .wavs, then compress the wavs into flacs.

My discs were converted to flac long ago (one file per track, not as wav + cue). To use the virtual method starting from flac files, I decode the flac files back to wavs (any flac encoder can do this), create a cue sheet for the set (EAC can do this), mount the .cue in Daemon Tools, play it with WMP, then grab the HDCD decoded output as usual. Seems to work OK and it means I don't have to get my HDCD discs out of storage. Too bad .cue doesn't support flac files directly....if I could trick WMP into thinking a set of flac files was a 'CD', that would be great.

 

How do you use the command line tool, SiriusB or tot

 

That's exactly what I do when I have a new disc that I know is an HDCD. Discs I've already ripped are usually in a flac+cue pair -- so I use a similar method to what you describe in your post, except the decoded audio is already in one file (and then I just tweak the cuesheet by hand to refer to that).

Some software will read flac+cue files, as long as the cue file is edited to change the .wav extension to .flac, but unfortunately Daemon Tools doesn't seem to be one of them. (I seem to remember reading somewhere that the developers didn't want to add this feature since they didn't want to have to embed decoders for every single compression format out there into Daemon Tools.) And too bad that WMP's HDCD decoder only seems to kick in while playing CDs (either real or faked by Daemon Tools)...

 

I actually used linux and wine, but I would assume in Windows typing

hdcd.exe < orig.wav > new.wav

to the console window would do the trick (using double quotes around the file names if they contain spaces).

 

Here is a screenshot of exactly what to type to load the hdcd.exe command line tool. Where C:\filename is indicated, is the location the hdcd.exe file AND the original wav file are located, preferrably at the place on the hard drive the command line tool defaults at. If it detects that the source is HDCD, it will state Detected HDCD, if not, it will indicate "The filename, directory name, or volume label syntax is incorrect. The outcome of the correct HDCD source is the true HDCD decoded file. As indicated below, it's best that the name of the .wav file has no spaces in between each word.