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Forum: Coders. Asm / Hardware 10 February 2021, 14:15
Replies: 234
Views: 13,493
Posted By buggs
Thanks for the reference. I'll have a closer look...

Thanks for the reference. I'll have a closer look at some point. To make such approaches viable for comfortable realtime operation on the 68k (i.e. something like MP3 on 060 + filtering), I'm...
Forum: Coders. Asm / Hardware 09 February 2021, 13:37
Replies: 234
Views: 13,493
Posted By buggs
I did experiment with 8 Bit dithering and noise...

I did experiment with 8 Bit dithering and noise shaping (at 44.1 kHz) and wasn't satisfied by the results I got from the Lipshitz approach. In the end, I've combined 14 bit with TPDF dither and 3 tap...
Forum: Coders. Asm / Hardware 09 February 2021, 10:02
Replies: 234
Views: 13,493
Posted By buggs
The equipment is not overly important. I did my...

The equipment is not overly important. I did my earlier measurements with the Line-In of a stock MBPro. Frequencies beyond 16 kHz (if attenuated by the receiving end) don't contribute much N to the...
Forum: Coders. Asm / Hardware 08 February 2021, 09:15
Replies: 234
Views: 13,493
Posted By buggs
Actually, I have. My semi-private paper on the...

Actually, I have. My semi-private paper on the matter which I've mainated for several years has been linked (http://bax.comlab.uni-rostock.de/dl/Paula_SystemTheoretic.pdf) multiple times already here...
Forum: Coders. Asm / Hardware 07 February 2021, 21:31
Replies: 234
Views: 13,493
Posted By buggs
Joke of the day coming from the one who's defying...

Joke of the day coming from the one who's defying established proven science to re-invent the wheel with his silly little amateur approach to something basic like SNR calculation.
Forum: Coders. Asm / Hardware 31 January 2021, 14:41
Replies: 234
Views: 13,493
Posted By buggs
In theory and practice, yes. That's what 1 Bit...

In theory and practice, yes. That's what 1 Bit A/D and D/A converters do (Sigma-Delta Modulation). You have two degrees of freedom with audio: amplitude and time. So with error feedback, you can...
Forum: Coders. Asm / Hardware 24 January 2021, 13:51
Replies: 234
Views: 13,493
Posted By buggs
Careful here. I said that I compute the SNR...

Careful here. I said that I compute the SNR directly from the PSD. I only mentioned Matlab's snr as a reference, which in turn directly and correctly applies in this case.
Correct observation, wrong...
Forum: Coders. Asm / Hardware 19 January 2021, 01:22
Replies: 234
Views: 13,493
Posted By buggs
I do use stereo calibration. You'll find my...

I do use stereo calibration. You'll find my proposal for stereo calibration in https://aminet.net/package/driver/audio/AHI-Paula or alongside EP. Basically, the updated calibration utility outputs a...
Forum: Coders. Asm / Hardware 19 January 2021, 00:32
Replies: 234
Views: 13,493
Posted By buggs
I'm currently thinking about possible avenues in...

I'm currently thinking about possible avenues in that direction, too.

Your proposal boosts the LO channel by a given factor. While that won't help with the fundamental problem of HI-channel...
Forum: Coders. Asm / Hardware 17 January 2021, 21:08
Replies: 234
Views: 13,493
Posted By buggs
The shorthand 6.02*Bits does not apply to these...

The shorthand 6.02*Bits does not apply to these tests because it implies a uniform PDF of the signal to be quantized (you should know that). Instead, 6.02*Bits+1.76 dB is appropriate for the PDF of a...
Forum: Coders. Asm / Hardware 16 January 2021, 21:53
Replies: 234
Views: 13,493
Posted By buggs
Can you please stop toting these numbers around?...

Can you please stop toting these numbers around? You should have realized by now that they are utterly wrong. No, they are not a little off, and they are not caused by your setup being inappropriate....
Forum: Coders. Asm / Hardware 16 January 2021, 21:23
Replies: 234
Views: 13,493
Posted By buggs
Yes, the dB(A) curve or the later ITU-R 468 are...

Yes, the dB(A) curve or the later ITU-R 468 are quite common for psychoacoustic weighting of the SPL. In this case, it probably wouldn't do poor old Paula any good, I guess. There's little relevant...
Forum: Coders. Asm / Hardware 14 January 2021, 18:02
Replies: 234
Views: 13,493
Posted By buggs
The question about the A600 has been settled...

The question about the A600 has been settled earlier in here, but I'd like to add some words. I extracted the previously stated numbers for the A600 filter from a schematics PDF that's circulating,...
Forum: Coders. Asm / Hardware 14 January 2021, 17:58
Replies: 234
Views: 13,493
Posted By buggs
Thx. Honestly, I did not advertise it's existence...

Thx. Honestly, I did not advertise it's existence because I've more or less maintained it as journal for me and also because it didn't get a thorough peer review.
Forum: Coders. Asm / Hardware 14 January 2021, 17:47
Replies: 234
Views: 13,493
Posted By buggs
My hypothesis is that the volume setting is...

My hypothesis is that the volume setting is updated just like the regular volume register alongside the switch from the previous sample to the next one. But I did not (oscillo)scope it out. Maybe...
Forum: Coders. Asm / Hardware 14 January 2021, 17:41
Replies: 234
Views: 13,493
Posted By buggs
In the end, (Re)Sampling is amplitude modulation,...

In the end, (Re)Sampling is amplitude modulation, just with an impulse train instead of the customary complex exponential (or cosine). Since in the case of digital resampling the originating signal...
Forum: Coders. Asm / Hardware 14 January 2021, 00:48
Replies: 234
Views: 13,493
Posted By buggs
True, any frequency well below the 3dB cutoff is...

True, any frequency well below the 3dB cutoff is unimpeded.

The pre-emphasis has to compensate for 15 dB attenuation around 18 kHz (A500/2000/4000), 12 dB for A3000 and 4 dB for A1200. The latter...
Forum: Coders. Asm / Hardware 14 January 2021, 00:15
Replies: 234
Views: 13,493
Posted By buggs
One side effect of the amplitude modulation is...

One side effect of the amplitude modulation is that the samples are subject to 55.4 kHz resampling which Paula needs for the differential PWM. At higher sampling rates, the intermodulation byproducts...
Forum: Coders. Asm / Hardware 13 January 2021, 23:03
Replies: 234
Views: 13,493
Posted By buggs
Paula's capabilities wrt. actually achievable bit...

Paula's capabilities wrt. actually achievable bit depth in the 14 Bit mode are in the ballpark of 10-11 bit with ECS Paula, depending on the Amiga model. Two major factors contribute to the observed...
Forum: Amiga scene 08 January 2021, 21:20
Replies: 31
Views: 1,495
Posted By buggs
Granted, my way to hook up my Amigas to the net...

Granted, my way to hook up my Amigas to the net is quite probably not the most common one.

My A4000's and the A3000 do have a DIY Z-III Ethernet card (co-development by matze@a1k and me).
...
Forum: Nostalgia & memories 09 October 2020, 20:27
Replies: 292
Views: 14,676
Posted By buggs
Well, running classic MacOS on an Amiga was...

Well, running classic MacOS on an Amiga was something quite unique back in the day. Shapeshifter and Fusion allowed to run a second operating system in parallel to AmigaOS, pretty much as precursors...
Forum: Nostalgia & memories 09 October 2020, 19:27
Replies: 292
Views: 14,676
Posted By buggs
I agree. Except one point: ...

I agree. Except one point:


http://bax.comlab.uni-rostock.de/dl/Amiga_Shapeshifter_Word.JPG
Forum: support.Hardware 10 August 2020, 23:19
Replies: 14
Views: 2,040
Posted By buggs
This is a WIP 040/060 card by M. Heinrichs for...

This is a WIP 040/060 card by M. Heinrichs for A3000/A4000 which was recently announced at A1k.org. It'll most probably be open source once it works as intended. The card is not aimed to be...
Forum: support.Hardware 10 August 2020, 11:26
Replies: 14
Views: 2,040
Posted By buggs
I know that this thread is a little stale....

I know that this thread is a little stale. Nevertheless, I think that I do have some useful addition to the content in here.

Please don't rely on the resistance numbers posted in the 68060 user...
Forum: Retrogaming General Discussion 18 July 2020, 15:05
Replies: 124
Views: 7,105
Posted By buggs
I can't say for sure what went wrong. My wild...

I can't say for sure what went wrong. My wild guess is an integer overflow that resulted in sign changes which would fit the hissing you've described.
Forum: Retrogaming General Discussion 18 July 2020, 00:43
Replies: 124
Views: 7,105
Posted By buggs
Yes, Paula does not have a built-in...

Yes, Paula does not have a built-in interpolation. By my reckoning this should be seen in the historic context. Paula was a chip that came up at a time where synthesizer chipsets were commonplace and...
Forum: Retrogaming General Discussion 09 July 2020, 20:21
Replies: 124
Views: 7,105
Posted By buggs
Frankly, I did not dive into this as of yet. Most...

Frankly, I did not dive into this as of yet. Most parameters are latched and I would assume for now that this applies to the xVOL as well (until proven otherwise).
Actually, I sincerely hope that...
Forum: Retrogaming General Discussion 09 July 2020, 20:02
Replies: 124
Views: 7,105
Posted By buggs
Well, I bought my Cybervision64 around 1995 and...

Well, I bought my Cybervision64 around 1995 and never had much motivation to go back to plain ECS/AGA screen modes for more than occasional testing. But you are right about the severe ECS...
Forum: Retrogaming General Discussion 09 July 2020, 18:00
Replies: 124
Views: 7,105
Posted By buggs
Yes, exactly. Since the OpAmp behind Paula is...

Yes, exactly. Since the OpAmp behind Paula is tuned for impulse inputs, you can't use wider impulses for the desired lower Amplitude. That's the explanation why Paula subtracts the previous impulse...
Forum: Retrogaming General Discussion 06 July 2020, 16:23
Replies: 124
Views: 7,105
Posted By buggs
I've never managed to get the theoretical limit...

I've never managed to get the theoretical limit of 55.4 kHz to work properly for me (PAL).

One addition to your post: The ability to get more than 28kHz DMA rate is not exclusive to AGA in the...
Forum: Retrogaming General Discussion 06 July 2020, 14:19
Replies: 124
Views: 7,105
Posted By buggs
Ah, thanks. I'll correct it. Since I don't own an...

Ah, thanks. I'll correct it. Since I don't own an A600, I had to resort to documents I found around the net.


I think it's fair to mention why the actual total frequency response of the Amigas is...
Forum: Retrogaming General Discussion 06 July 2020, 14:00
Replies: 124
Views: 7,105
Posted By buggs
Sure, you could do PWM at any reference clock....

Sure, you could do PWM at any reference clock. But the Amiga doesn't work that way. Paula does differential outputs of 3.5 MHz pulses only, i.e. it resembles a near ideal upsampler whose pulses are...
Forum: Retrogaming General Discussion 06 July 2020, 13:43
Replies: 124
Views: 7,105
Posted By buggs
Yeah, well. It's true that you get a lot of...

Yeah, well. It's true that you get a lot of overlaps within the dynamic range when using the Volume Modulation feature to increase the amplitude modulation instead of a classic static 14 Bit setup...
Forum: Hardware mods 02 June 2020, 20:22
Replies: 17
Views: 12,040
Posted By buggs
Yes, indeed. I remember that I had to cut said...

Yes, indeed. I remember that I had to cut said jumper wire when I used the Kick 2.04 ROM I've bought in 1991 on the Commodore fair in my Rev.6A.

So in a nutshell: 1.2,1.3 and 2.04 (maybe 2.05)...
Forum: support.Apps 04 May 2020, 14:33
Replies: 33
Views: 4,237
Posted By buggs
I know from whom I got that Virus a couple of...

I know from whom I got that Virus a couple of years back. Never accepted anything from him again. Since then, I'm in the habit of checking my Amigas on occasion.




That option is a regular...
Forum: support.Apps 02 May 2020, 15:30
Replies: 33
Views: 4,237
Posted By buggs
Thank you Gulliver. I appreciate the information,...

Thank you Gulliver. I appreciate the information, which is quite interesting and sad at the same time.

I did a little experiment to put my observations into perspective (and numbers) by compiling...
Forum: support.Apps 01 May 2020, 23:35
Replies: 33
Views: 4,237
Posted By buggs
TBH, the main reason for my rewrite of JFIFdt was...

TBH, the main reason for my rewrite of JFIFdt was JPEG decoding performance on Vampire cards. The available 68k CPUs have quite a hard time to decode JPEG files in a timeframe that users are willing...
Forum: Member Introductions 16 April 2020, 19:17
Replies: 35
Views: 4,489
Posted By buggs
With the assumption that you're in for gaming I'd...

With the assumption that you're in for gaming I'd suggest another 512k RAM in the trapdoor slot.

Many A500 games require 1 MB RAM as that was the most common configuration back in the day.
...
Forum: Member Introductions 16 April 2020, 15:20
Replies: 35
Views: 4,489
Posted By buggs
While a Rev.8 or Rev.8a board should be in the...

While a Rev.8 or Rev.8a board should be in the case for obvious reasons, you might not be so unlucky with your purchase. Most A500+ boards do suffer from battery damage these days. In many cases,...
Forum: request.Music 28 March 2020, 21:30
Replies: 48
Views: 11,419
Posted By buggs
I notice quite a lot of blame being cast in this...

I notice quite a lot of blame being cast in this thread. Interestingly, all of it in the wrong direction.

It's neither modplayers, nor other trackers/players but plain and simply Protracker...
Showing results 1 to 40 of 107

 
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