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HDCD Decoding ?

Recently, I have noticed that the specifications for CD players sometimes mention that they are compatible with HDCD CDs. I thought that HDCD died about ten years ago. But HDCD CDs have always been playable on any CD players; albeit not all CD players would decode the HDCD formatting because that required a special digital filter from Pacific Microsonics.

Several years ago, when HDCD first appeared, Pacific Microsonics required that anyone licensed to use their HDCD filter had to install automatic attenuation in their players for ALL non-HDCD discs. This was not necessarily a good thing.

When a 21st century CD player will read HDCD discs, it may or may not perform the automatic change in volume as a result. The net impact in older HDCD players was that all normal (non-HDCD) discs were attenuated. I own a few hundred CDs and only about 6 of them are HDCD. I expect that now in the year 2013, this is no longer a problem regarding the Pacific Microsonics HDCD filter. My guess is that current players are not using a Pacific Microsonics filter.

Perhaps "compatible with" is simply a reminder that the CD player will play the older HDCDs as regular CDs?

What says the group mind?
poetcatullus
poetcatullus OP
53 posts
 
This issue about which I raise concerns was well-known at the time and mentioned in Stereophile every time they reviewed a piece of equipment with HDCD capability. They generally made a point of praising the manufacturers who chose to implement the attenuation (required by the Pacific Microsonics HDCD license agreement) in the ANALOG domain rather than in the DIGITAL domain by simply cutting off a bit (thereby "punishing" all the normal CDs in ones collection for the benefit of the HDCDs).

There were certain pieces of gear where one could contact the manufacturer directly after purchase and they would accommodate the purchaser by telling them how to open up the unit and move a jumper, thereby undoing the compromise to their regular CD collection by reversing the attenuation and having all CDs play at their natural volume levels.
rja's avatar
rja
2,369 posts
 
HDCD has belonged to Microsoft for a while now. Have no idea what they're up to with the technology. Maybe just chucked it in the back room. Why they bought it I don't know.
poetcatullus OP
53 posts
 
Excellent point, Rja!

I am seeing current models of CD (and DVD, etc.) players mentioning that they are compatible with HDCD CDs. This is what sparked my question(s) and caused me to start this thread. I only own a few HDCD CDs, but a few hundred regular CDs. I want to be certain that any player I purchase will not compromise the sound of my CD collection in favor of the HDCD discs.

Please allow me to emphasize the following: The aforementioned attenuation was never necessary to help HDCDs sound their best. The attenuation was done because HDCDs are naturally slightly lower in sound volume than standard CDs. So why not simply adjust the volume and leave the regular CDs alone?

Because: When Pacific Microsonics first implemented HDCD, they were afraid that the lower volume might cause a perceived (but imaginary) inferiority of HDCDs. So, they made it part of their license agreement that the devices using their HDCD digital filter (which was an excellent filter) would automatically lower the volume of all standard CDs as a means of leveling the playing field. This was often done by throwing away one of the bits of information from the standard CDs playback.
dtc's avatar
dtc
1,047 posts
 
For those who are going to PC audio, there is software, such as dBpoweramp, that will do the 16 bit to 20 bit conversion for HDCDs. It then pads it with zeros to 24 bits. You just check a box when you do the rip.
poetcatullus OP
53 posts
 
So, how are we to discover what HDCD means and how it is implemented in a 21st century CD player? I have emailed one manufacturer about this but have not heard back from them yet. They may need to consult one of their older engineers who was on the job when this all started. Was that sometime in the early 1990s?
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