HDCD: a function of DAC and/or transport?
Apr 20, 2004 at 7:04 AM Thread Starter Post #1 of 9

TrevorNetwork

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As subject. Can any transport extract the enhanced resolution from an HDCD and output it via a coaxial digital port to an HDCD-supporting DAC?

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Trevor
 
Apr 20, 2004 at 7:06 AM Post #2 of 9
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AFAIK, yes. The extra resolution is encoded into the high end of the regular 16-bit signal, so any normal CDP should pass along the same signal to the DAC. It is up to the DAC to decode the extra data and enhance the signal with it.
 
Apr 20, 2004 at 2:45 PM Post #3 of 9

Canman

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Yes, the HDCD signal is transport independent. It is carried in the normal 16 bit signal and decoded in the digital filter, prior to the DAC chips. The CD players or DACs that decode HDCD all use the same Pacific Microsonics (now Microsoft) digital filter chip. The chip was changed once a few years back (I believe the PMD-100 to the PMD-200).
 
Apr 20, 2004 at 2:49 PM Post #4 of 9

lan

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The coding is in the LSB (Least Significant Bit) of the 16bits. So you can even copy the disc, make WAVs on your harddrive, etc. and it will be in tact.
 
Apr 20, 2004 at 5:54 PM Post #6 of 9

Super-Gonzo

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I wish there was a way to take the 16-bit wav and decode the hdcd content to a real 20-bit wav... then I wouldn't need a hdcd compatible dac, just a dac that can decode 20 bit PCM.

I'm assuming this is what WMP9 does for its HDCD implementation. I wonder what it does when it has an hdcd disc, but an output device only capable of 16 bit resolution?
 
Apr 20, 2004 at 6:11 PM Post #7 of 9

lan

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Lossless should be fine as long as the decompression goes back to the original WAV.

As for decoding HDCD to a file... You'd need a software decoder which only WMP9 can do. You can then record the output of the digital output. The problem is that it's real time so it'll take a while. I also think it would work best with an RME soundcard since it bypasses kmixer even in WaveOut of DS output. WMP goes through kmixer resampling with a regular soundcard probably. Recording a resampled sound from kmixer defeats the purpose.
 
Apr 20, 2004 at 6:39 PM Post #8 of 9

Super-Gonzo

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Quote:

Originally Posted by lan
...WMP goes through kmixer resampling with a regular soundcard probably. Recording a resampled sound from kmixer defeats the purpose.


Agreed, not much point in decoding 20 bits only to immediately resample to 16 again.
 
Apr 20, 2004 at 7:06 PM Post #9 of 9

lan

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Quote:

Originally Posted by Super-Gonzo
Agreed, not much point in decoding 20 bits only to immediately resample to 16 again.


The resampling, which is related to sample rate, is different issue than the one you mentioned about bit depth. I'm just saying the bit depth issue is kind of irrelevant as long as there's the sample rate conversion issue.

There is a setting to decode to 24bit in WMP9. I guess if it's unchecked it stays 16bit. I can do a bit resolution analysis on the recorded file to see what happens with the bits though. I can't do it right now so i'll have to get back later on that.
 

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