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post #541 of 545
Quote:
Originally Posted by fiftyonefifty View Post

 

 

When using the foobar script [%__bitspersample% bits] and playing HDCD encoded 16 bit files or the HDCD CD itself, 24 bits is displayed in the status bar (for me anyway). Do you think this is because of that 1 bits worth of extra range and foobar shows 24bit because it is not capable of displaying 17 or 20, etc?

Dear 51-50,

 

Yes, that is exactly the case. There was a period when playback DAC chips could only reach 16 bits. Then I believe it was Denon that released the first 18-bit chip. This started a numbers race. Within only a few years, EVERY DAC was claimed to be at least 24 bit, even the very least expensive and lowest actual performance chips. There was a "numbers" race that lasted only for a few years. For the last ten years or so, one cannot find an audio chip that is not rated at least at 24 bits of resolution.

 

Today a new "numbers" race is starting, and many DAC chips are claiming that they will produce "32-bit resolution". This is fairly silly in one aspect. 32 bits of resolution would reach a dynamic range of over 192 dB!!! This is absolutely not possible. But on the other hand it also means that it can accept up 32 bits of data from the oversampling digital filter. It is possible that this would sound very slightly better than the way that the same data is presented to a 24-bit DAC. The length of the data exceeds 24 bits, so it must be reduced to the correct length either by truncating, rounding, or dithering. All of these have some audible disadvantages, so it may sound better to reduce it to 32 bits, whereas the audible disadvantages of reducing the sample length from the digital filter all the way to 24 bits may have an audible disadvantage.

 

In addition, the processing inside the software player is done with bytes. One byte equals 8 bits. So it requires a lot of extra work to display the number of bit is increments less than 8 bit increments.

 

Hope this helps,

Charles Hansen

Ayre Acoustics, Inc.

www.ayre.com


Edited by CHansen - 6/17/13 at 12:41am
post #542 of 545
Quote:
Originally Posted by CHansen View Post

Dear 51-50,

 

Yes, that is exactly the case. There was a period when playback DAC chips could only reach 16 bits. Then I believe it was Denon that released the first 18-bit chip. This started a numbers race. Within only a few years, EVERY DAC was claimed to be at least 24 bit, even the very least expensive and lowest actual performance chips. There was a "numbers" race that lasted only for a few years. For the last ten years or so, one cannot find an audio chip that is not rated at least at 24 bits of resolution.

 

Today a new "numbers" race is starting, and many DAC chips are claiming that they will produce "32-bit resolution". This is fairly silly in one aspect. 32 bits of resolution would reach a dynamic range of over 192 dB!!! This is absolutely not possible. But on the other hand it also means that it can accept up 32 bits of data from the oversampling digital filter. It is possible that this would sound very slightly better than the way that the same data is presented to a 24-bit DAC. The length of the data exceeds 24 bits, so it must be reduced to the correct length either by truncating, rounding, or dithering. All of these have some audible disadvantages, so it may sound better to reduce it to 32 bits, whereas the audible disadvantages of reducing the sample length from the digital filter all the way to 24 bits may have an audible disadvantage.

 

In addition, the processing inside the software player is done with bytes. One byte equals 8 bits. So it requires a lot of extra work to display the number of bit is increments less than 8 bit increments.

 

Hope this helps,

Charles Hansen

Ayre Acoustics, Inc.

www.ayre.com

 

Makes perfect sense CHansen, thanks for chiming in. I'm curious as to what you think about a flagged 16 bit HDCD file where there is no PE or LLE, just the TF ticks on and off. The foobar script [%__bitspersample% bits] displays this as 24 bit as well.

post #543 of 545
Quote:
Originally Posted by fiftyonefifty View Post

 

Makes perfect sense CHansen, thanks for chiming in. I'm curious as to what you think about a flagged 16 bit HDCD file where there is no PE or LLE, just the TF ticks on and off. The foobar script [%__bitspersample% bits] displays this as 24 bit as well.

 

Hello 5150,

 

There have been many attempts by several different people to reverse engineer the HDCD decoding algorithm. Every single one of them were successful in finding the three different flags in the "subcode" one for PE, one for LLE, and one for the TF. And of course, they all have "activity", so I think everyone just assumed that they needed to be decoded.

 

I have known about the sleazy marketing tactics of HDCD since before 2000, so when every one of the reverse engineering people were saying there was activity in the TF flag but that they couldn't figure out how to decode it, I started to look into it. I read every single piece of literature they put out (including the patents), and without exception, they implied that there were two conjugate filters, but they never actually flat-out said so.

 

This set my alarm bells ringing. Why not brag a bout such a feature if it really had it? My suspicions grew and I made several posts in public forums where I expressed by skepticism. Nobody every came out and correct or contradicted me, which made me even more suspicious. So I finally contacted one of the developers and asked him and he admitted that there was only one playback filter. (Although the Spectral 4000 CD player claims that an improved version of this single filter was developed by Keith Johnson for this machine. Please refer to http://spectralaudio.com/bulletins/0806.pdf )

 

I contacted him again to ask why they had included the flag? Were the planning to include two filters but run out of time and money before it could be implemented? This didn't make sense, as when the PMD-200 was introduced they could have easily have added it.

 

My own suspicion is that they wanted the HDCD system to be a single patented package. And Ed Meitner, then at Museatex, now of EMM Labs, had beaten them to the punch! Ed had already patented a two-filter playback system. So they could only patent the two-filter scheme on the record side! My guess is that they had planned to implement a two filter playback scheme, had already set up the encoding bits, and then either found out about the patent or possibly knew about the patent and were hoping to license but were unable to.

 

The bottom line is that just as the TF bits n the subcode are a left over legacy of some unknown yet unimplemented plan, the fact that Kode 54's HDCD plug-in decoder for Foobar expands to 24 bits are part of a left over legacy code. If Kode 54 gets bored some day, he could easily make some changes so that ONLY HDCD titles with PE and/or LLE are expanded. And 18 bits would be MORE than enough. It's just that there is no standard for an 18 bit (or even a 20 bit) format.  The next jump that most software players will handle is 24 bits.

 

Hope this helps,

Charles Hansen

post #544 of 545

Charles - That helps alot. Great info there. Thanks so much!

post #545 of 545

If you are still updating the list. Here is an album I owned with HDCD, Artist: September (Petra Marklund) - Album: September. 

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