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That would be you

Christine wrote, "You have absolutely no proof that what was described in the patent has not been implemented." Just as you have no proof that it was implemented. Without further information, we will have to agree to disagree.

On your second point, you stubbornly persist in being flat-out wrong. You wrote, "The Microsoft implementation of HDCD automatically attenuates the digital signal by 1 bit (or approximately 6dB)."

This is incorrect. Here is the text from the Microsoft document explaining gain scaling:

A key feature of the HDCD process is Peak Extend. Peak Extend increases the dynamic range of
Redbook CDs by 6dB. The Peak Extend feature is selectable on the Model 1 (or Model 2) HDCD
encoder - the recording or mastering engineer has the ability to set Peak Extend ON or OFF on
the Model 1 HDCD encoder. So it is possible to have HDCD recordings with, or without Peak Extend.
Because Peak Extend adds 6dB of dynamic range to the top end, the “average” decoded
signal level will be 6dB lower than an HDCD recording without Peak Extend, or a non-HDCD
recording. Unless the decoded level of Peak Extended and non-Peak Extended recordings are
matched using Gain Scaling, Peak Extended Recordings will be 6dB quieter than non-Peak
Extended recordings and this is not acceptable. All HDCD decoders must either 1) lower the gain
of non-HDCD recordings and HDCD recordings without Peak Extend by 6dB, or 2) raise the gain
of the Peak Extended recording 6dB. This is a requirement of the HDCD license agreement.

So contrary to your unfounded assertion, the signal is *only* attenuated during playback if it was recorded with "peak extend" enabled. Therefore you *cannot* determine if a recording was recorded with "peak extend" enabled simply by examining the peak signal level of the decoded output.

However, I just realized that there actually *is* a relatively simple way to tell if a recording was made with "peak extend". Pin 5 on the PMD-100 goes "high" when the recording employs "peak extend". (At least this is the case when analog gain scaling is employed in the DAC. Tying pin 19 low on the PMD-100 enables internal digital gain scaling, but the datasheet doesn't say if this disables the output of pin 5 or not.)

So if one had a DAC with the PMD-100 (it may need to use analog gain scaling for this to work), then it would be easy to tell what percentage of HDCD discs use "peak extend".

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