[LouT]

Quote:

chances are though, that WMP does not play decoded HDCD 20bit stream to S/PDIF (or does it?), so we might be getting 14bit compressed output after all

It is decoding it in wmp10, although it has to upconvert the file to 24 bit to capture all the information. Spdif does get it all. However the quality job it is doing is a wee bit suspect. It has been proven above that the file has more information for sure, see the dynamic range graphs.

If it is doing 80% of the job a hdcd chip does then it is still better. There is information on the net through a google search that spells out that it is not all roses though. Using 24 bit has some disadvantages too. Yet the total package with all things considered is in fact "better" I'll come back and edit for a bit more detail around the negative aspect if I can makes sense of it, as it get very technical. (for me at least)

Lou

 

[jcx]

where does this 14/15 bit garbage come from?

PMD100 datasheet:

"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."

It does appear that Microsoft may not be fully implementing the HDCD variable digital filtering as Chronotron's waveout tool only captures 44.1K data, probably only the dynamic range expansion funtionality is implemented

the PMD100 datasheet further states that 2XFs @24 bits is slowest, undithered output mode for HDCD decoded data so we should expect to see 88.2K @24 bits from a fully compatabile decoder

 

[Eric Carroll]

Quote:

Originally Posted by regal /img/forum/go_quote.gif And no its no longer a HDCD at this point, it is a 24bit 44.1k disc with 20 bit resolution. ... It creates something akin to an HDAD (24/96), but not quite as good. Any other questions ?

Actually, yes.

A long thread on ripping HDCD for playback on the the Slim Devices Transporter and Squeezebox has been running on the SD forums based on this thread.

We have had some success based on these instructions: we have successfully captured WAVEX files (using WMP9) at 24bits, 44.1KHz, with the HDCD icon lit using 24b audio card with the 24b tick box enabled. So we expect to find 20b resolution audio inside the file.

Examing the 16b rip against the 24b HDCD capture shows the 24b capture being about -6 dB down compared to the 16b rip, perhaps more, using Audacity. Its quite noticable.

We are still investigating (cause we would really like the 20b resolution on the 24b files for our Transporters and Squeezeboxen), but it is looking significantly to us like this file is just 16 bits with a another 8 bits of zero padding added on. We have not found anything conclusive that says the extra dynamic range is present.

How can we confirm that the HDCD decode is actually using the 20b resolution? How did you confirm it?

Any help appreciated!

 

[regal]

feckn_eejit had a thread where he analyzed the files and found 20 bit dynamic range. http://www.head-fi.org/forums/showthread.php?t=221104

I think wavex may be your problem. Also it only works when playing a CD in the optical drive, you can't rip it first.

 

[Eric Carroll]

Regal,

Thanks for responding.

First, understand fully on the playing CD issue. When playing the HDCD directly via WMP9, we get the HDCD icon lit. We are not ripping the file we are playing it.

.wav format files come in two versions: a standard header and an extended header. the WAVEX format is the extended header and comes straight out of the chronotron plug in. I can convert that to standard WAV format if required (audacity knows both formats) but the major difference in levels remains.

I will check out the other thread you reference.

 

[Eric Carroll]

Weird that is not what we are seeing at all.

Here is my Audacity screenshot.


The top trace is the original 16b rip. The bottom trace is the 24b HDCD capture using the chronotron plugin.

I cannot explain why the 24b version's levels are so much lower. This is the reverse of what feckn_eejit's thread shows.

Any ideas?

 

[parrot5]

Quote:

Originally Posted by LouT /img/forum/go_quote.gif Another tidbit is that although in WMP 24bit mode the data is large and the filesize is a 24 bit wave...the hdcd decode light does not light for me. If I take the 24 bit option off and just let it play the hdcd decode lights up. This produces a 16 bit wave file though.

I'm using WMP 11 on Vista, and I see the same thing.

set to 16 bit: HDCD light, louder.
set to 24 bit: NO light, a lot softer.

So I believe the 24bit one does decode HDCD correctly, it's just that it "forgot" about the light.

Another thing is that Chronotron's plugin doesn't work in WMP11-on-Vista. I need to re-install XP and WMP10 to rip all my CDs again... argh...