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HDCD feedback and information thread


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41 minutes ago, vortecjr said:

They sure do. HDCD is both nowhere and everywhere if you look for it:) I didn't look at the code...

https://ffmpeg.org/ffmpeg-filters.html#hdcd

 

OK, that doesn't mean it can be used though... But good to know that it's there so it can be used for decoding rips in case I still encounter HDCD somewhere (I don't buy CDs anymore).

 

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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21 hours ago, tmtomh said:

The way the Reference Recordings blurb is written, it is not clear what they mean when they say they still currently use HDCD in the production of their high-res recordings. If they do, I would guess that probably means they use Pacific Microsonics ADC units - which happen to be HDCD capable - to digitize their recordings. But I would be very surprised if they enable the substantive features of it - Peak Extend and Low-level Range Extend. It would hardly be necessary with high-res content, since high-res provides more bits and more dynamic range than HDCD (24 bits vs 20 bits), and again, AFAIK no consumer playback software or hardware could decode those features if they were embedded in the least significant bit of a 24-bit stream.

 

In other words, one can use a Pacific Microsonics ADC for recording, and enable HDCD but not actually use any HDCD features - which means the resulting disc/file will trip an HDCD flag but there's no actual HDCD data or features in the digital content. In fact, I believe one can even use a PM ADC and simply turn off its HDCD features altogether, meaning one can record non-HDCD content using a PM unit. In that case, one might still say "we use HDCD" when they really just mean "we use PM equipment to digitize our recordings." I suspect one of these two scenarios is what happens with Reference Recordings' high-res material.

 

So that leaves the digital filters - both the filters used in the ADC during recording, and the digital filters built in to any HDCD-certified/capable hardware playback device. Part of HDCD's claim was that the digital filters built in to HDCD hardware players were special/high-precision/very good. And presumably they were considered to match up well, or be complementary, to the filtering used by the Pacific Microsonics ADC.

 

Software HDCD decoders/players do not, AFAIK, necessarily have such filters - or if they have multiple filters choices, I don't know that they automatically switch to HDCD filters when playing back files that were ripped from HDCD discs.

RR advised that they use the HDCD flag (so the light lights up) on our HRx discs- but no HDCD decoding is possible in high resolution files. The files on HRx discs are WAV files, at 176.4 kHz/ 24 bits. They use the HDCD flag as a test that the files were copied properly.  HDCD processing and decoding only works on compact discs, or on 44.1/16 bit WAV files, encoded with HDCD

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  • 2 months later...

I apologize if I am repeating anything said above, but here's what I know about HDCD.

 

The wikipedia article is here:

https://en.wikipedia.org/wiki/High_Definition_Compatible_Digital

 

From that article:

"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. "

 

So the discs are compatible with both hardware players that support HDCD and those that don't.

 

When you rip a CD to FLAC, for example, the HDCD decoding information is included in the rip.  There's no special rip required.

 

Not all HDCD discs are labeled as such, so you may already have discs that are HDCD.

 

With JRiver Media Center, you must re-analyze the lossless audio tracks in order for MC to know which discs were HDCD.  Here's the current topic on our forum:

https://yabb.jriver.com/interact/index.php/topic,121124.0.html

Jim Hillegass / JRiver Media Center / jriver.com

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