How to rip 20-bit CD(and retain all 20bits) Options

[ben]

I have a 20-bit Telarc CD, and would like to extract it onto my computer. However, I'm not really sure how to go about this without having the WAV truncated to 16-bit. I only have a 16bit soundcard right now, so it's going to get chopped off anyway, but I just want the original, unaltered music in the file.

Any ideas?

[Carlos G]

Would it be possible to "reverse engineer" the gain scaling part of HDCD, using WMP9 as the"black box" to test, so that it could be implemented in software decoders?

The quotes are from the "Gain Scale" paper in http://www.hdcd.com/partners/proaudio/articles.html .

The "mark" to activate gain scaling seems to be only one bit of the sample:

The Digital Gain Scaling solution requires 1 bit of DAC resolution to properly decode Peak
Extended recordings. This means that on non-HDCD recordings, the PMD-100 IC loses 1 bit of
resolution.

By trial&error, maybe is possible to find the right codes for the LSB. You feed WMP9 with test signals, until it activates the HDCD decoding. Or you feed WMP9 with a high amplitude signal, changing the LSB and try to find which changes of the LSB make an increase of the dynamic range. The codes are present in HDCD PCM streams, so by analysing them maybe it is possible to get a little help...

Peak Extend is a restorable, instantaneous soft peak limiter which has a direct one - to -one mapping so that it can be easily and quickly restored in the HDCD decoder. Because this operation is performed digitally, it has a precise and stable curve

So if there's a 1-to-1 relationship between input and output, it is possible to obtain the exact transfer funcion...

Then software decoders could convert the 16 bit HDCD signal to a 24 bit, range extended signal...

Carlos G.