Yes, I've got to be more patient with this Atom PC. It takes the processor, running at full pelt, quite a while to get all the AI pre-processing done.

In any event, Quad Anti Imaging sounds interesting... dry, dark and 'weighty'. It could sound very good on some systems...

However, I've just compared a 16/44.1 upsampled with QAI and then with QAP against the same native 24/192. There are no two ways about it; QAP sounds closer to the native 24/192 than QAI. The ambience is missing with QAI.

Mani.

I suggest that no one uses Quad with 'no upsampling'. I've just measured a pretty consistent -40dB to -50dB level going right beyond 80KHz. I'm assuming this due to aliasing. In any event, it looks pretty nasty, and probably isn't doing your electronics any good, especially if you're using amps with negative feedback.

' Quad Linear Interpolation' doesn't look too good either (but much better than 'no upsampling').

I can't get 'Quad Anti Imaging' to work right now, but I suspect it'd be fine.

'Quad Arc Prediction' looks very good, of course

Mani.

Peter, I can't get QAI to work! Having pressed play, I have waited for minutes with absolutely nothing happening. Is this my poor Atom processor showing its weakness?

Mani.

THANK YOU Peter! This is superb!!!

In 'Adaptive Mode', I'm getting most (if not all) of the naturalness of 'Special Mode' (zero digital 'glare') but without the hiccups.

With my modest Atom-based PC (the C.A.P.S.), I have the buffer set to 128 and Q1=2 (with Q1=1, I still get the odd click and pop, which also shows up in the log file).

This evening, I'll check your 'new' thoughts on the Adaptive Mode and QAI combo...

THANK YOU once again!

Mani.

That's because 'HDCD-encoding' includes a number of options, of which Peak Extension is just one. See my 'HDCD 101' thread if you're interested.

Mani.

I didn't know that. But then these 20/44.1 files wouldn't work with QAP, and that just wouldn't do!

Mani.

I'm using the RME 'Digicheck' software. The y-axis denotes the signal level (in dB below 0dB full scale), and the x-axis the frequency. So, as you can see, most of the music lies between 60Hz and 1Khz (for this classical piece at least). But if you look at 20KHz and beyond, you will see different amounts of information that each file contains. Although a sine wave at this frequency would be inaudible (certainly to me), the effects of having this extra HF information are clearly audible. Everything has more 'life'... even bass notes are more tuneful and better rounded.


You may well be right. But I can't measure pre- and post-ringing with the Digicheck software

Mani.

With Peak Extension ticked = 24 bits
With Peak Extension NOT ticked = 23 bits

Is this what you expected?

Mani.

PS. It's good to have Digicheck back!

Well, now that I'm using an RME card, I couldn't help having a look at the difference between QAI, QAP and native 24/192 material. I used two versions of the same track downloaded from Linn Records; one at 16/44.1 and the other at 24/192.

As you can see, QAP does a really good job of re-creating the HF information in the 24/192 file. But it isn't quite all there and (perhaps) as a result, it doesn't sound quite as good as the native 24/192 file.

FWIW, the missing HF information in the QAI file is easily audible - the music sounds flat compared to QAP and native 24/192. I'm pretty sure the spectrum would have been identical if I was just using the 16/44.1 file without QAI, but I wanted to be consistent. It's worth noting that 99.99% of people are feeding their DACs with 16/44.1 files with all information above 22.5KHz chopped off!

Note 1: I couldn't get QAI to play for more than 30 seconds or so, hence why the spectrum lower down isn't quite the same as the other two.
Note 2: The measurement at 81KHz for QAP was due to a 'click'/'pop' in the sound, which I still get from time to time with QAP.

I've replaced my Weiss AFI1 firewire interface with an RME AES32 PCI card. I forgot just how much I love the RME gear - the hardware and the TotalMix/Digicheck software. I appreciate the simple things, like having a properly terminated BNC wordclock input, which is so important when you're slaving the interface to the DAC, like I am.

Also, with Digicheck, I can verify that QAP adds extra HF information, smoothing the drop-off above 22KHz. (Interestingly, I'm measuring QAP at 23 bits, not 24!)

Another benefit is that my Special Mode Q1 value using my humble Atom-based PC has come down - I can now play with QAP at around Q1=160. But I agree with pedal in that finding a 'stable' value is difficult.


If you could make Special Mode less hardware-intensive, I'd be a very happy chappie...

Mani.

Not sure if I understood you correctly Peter, but with Arc Prediction active, the DAC will not attempt to perform any HDCD decoding. Why? Because the LSB that contains the HDCD flag has been changed.


There's more to HDCD encoding/decoding than meets the eye (see my 'HDCD 101' thread).

Technically, XXHE doesn't do any HDCD decoding - XXHE has no idea whether material is HDCD encoded or not.

Using the volume control in XXHE (in any player actually) will switch the HDCD decoding off in your BADA - not because the decoding is then performed in XXHE, but simply because the LSB that contains the HDCD flag has been changed. If this is the case, then no HDCD decoding is performed anywhere.

However, Arc Prediction in XXHE is very similar (maybe identical?) to Peak Extension in HDCD. But AP isn't for everyone. Indeed, some BADA users, like earflappin, prefer not using it (which from a theoretical point of view I can understand). FWIW, I love AP (Quad) with my DAC, even though it stops the 'official' HDCD decoding.

If I had a BADA, I would be inclined not to use the volume control in XXHE with HDCD-encoded material.

Mani.

earflappin,

I'm not sure that you ever got an answer to your question. I certainly don't have one.

What I have done though is to have a look at everyone's setup and the latency (Q1 value) they're getting in Special Mode. As you can see, my isochronous firewire setup (perhaps the closest to asynchronous USB here?) doesn't fare too well. It seems that PCI is the way to go...

Mani.

CORRECTION:

To get totally glitch-free sound playing a number of tracks on my new Atom-based PC, I have to set Q1 to around 2000. So, it may not be the firewire drivers afterall all!

In any event, I've ordered a new motherboard with 4GB RAM and an E8600 processor.

Mani.

Could this be a coincidence?

I've just tried 0.9y-6 on my laptop feeding the Weiss AFI1 interface. And the exact same thing happens. In Engine#4 'special mode', I have to set Q1 to the exact same level (569) in order to get glitch-free sound.

In 'normal mode' I can play at Q1=-1 no problem. I know that there is no correlation between the Q1 settings in 'normal' and 'special' modes. But I can't help thinking that my Weiss firewire drivers like 'normal mode' but don't like 'special mode' very much...

In any event, it looks like my new single core PC is at least as capable as my dual core laptop

Mani.

Well, to all of you who can use 'special mode' at really low Q1s... congratulations! I myself have totally glitchless QAP sound with a Q1 of 569 in 'special mode'. Perhaps a little high, but there you go.

I loved the previous Engine#4, with my own Q configuration of 3, 9, 15, 5, 10. But note that this remained in 'normal mode' - I could never get 'special mode' to work without distortion. Even in 'normal mode', the tonal balance just seemed right. But there did seem to be a downside, and that was a slight loss of dynamics. Now with the latest Engine#4 in 'special mode', I hear the same beautiful and natural tonal balance but with all the dynamics intact. And there really does appear to be more detail. Where on earth this could have come from, God knows.

If you can't get 'special mode' to work, my strong recommendation would be to change whatever you need to in order to get it working.

Mani.