A debate: PCM versus DSD

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Amazingly enough, BD supporters aren't wound up tin soldiers all with the exact same opinion on subjects.

PCM (Pulse Coded Modulation) represents audio as a series of instantaneous levels represented by a value (commonly 8 - 24 bits per value, 8Hkz - 192Khz sample rate).

DSD (Direct-Stream Digital) stores audio as delta-sigma modulated technique which represent audio as a series of 1-bit values. (e.g. SACD is 64x CD sample rate, or 2.8224 MHz)



In the Insider's Thread, it has been asked why Blu-ray didn't have DSD include in the spec. The question before us:

Given the Blu-ray disc capacity (not SACD), is DSD capable of better fidelity over LPCM?

My position: LPCM on Blu-ray can provide fidelity beyond reasonableness, so adding further complexity to the Blu-ray standard was unnecessary.

Consider 7.1 channel LPCM (the pinnacle of what we could expect) and a BD-50 disc:

96Khz/24-bit: 18.432Mbps - > 6 hours
192Khz/24-bit: 36.864Mbps - > 3 hours (actually, I think BD is limitted to 6 channel for 192Khz)

How could any audio equipment that a home user could reasonably be expected to be able to afford be able to deliver 192Khz/24-bit fidelity, let alone improve on it?

Gary