hdcd is just a trademark....not a format...like thx, or dolby....most current redbook cd's meet hdcd standards whether they pay to use the trademark or not.
Jaybo, check your facts. I was under the understanding that while HDCD is not a different format like SACD, there is extra sonic "information" on HDCD discs that can only be retrieved by HDCD compatible DACs.
HDCD starts with 88.2 khz sampling @ 20 bits. The HDCD encodes processes this data stream by performing sample rate conversion. Based on instantaneous signal content it then chooses from a collection of digital processes to reduce the 20 bit data to 16 bits. The encoder also modulates the low order sample bit to signal what process is in use at a given time.
The HDCD decoder contains a reconstruction filter that is a perfect conjugate of the filters used by the encoder for sampling and sample rate conversion. It uses the low order bit modulation to determine which process the encoder used for data reduction and applies the appropriate inverse function to restore the 20 bit data stream.
Non-HDCD dacs simply process the 16 bit data stream and ignore the extra information included in the low order bit modulation.
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