SuperPAULA - if you have experinece in amiga music please give feedback

[biggun]

Hi,

Thomas, and me did some brainstorming which sound capabilities make sense to include in the enhance PAULA chip of the NATAMI.

If you have experience in creating music then I would appreciate if you could participate in the discussion.

We want to include good enhancements into the new Paula chip. Of course the focus should be put on only putting important addition to the chip and not bloat it with unnecessary stuff.

As we know the original Paula had
- 4 channels (2 Left / 2 Right)
- each supporting 8 Bit samples
- and in addition to this 6 Bit Volume.
- The resulting audio output quality was 14 bit.
- All 4 channels used DMA to read their sample data.
- The DMA of two channels could be combined to read both
the sample and the volume values in for one channel.
- Doing this Paula could DMA create 2 channels with 14 bit.


The Natami New Paula:
- Audio output quality upgraded to 24 bit.
- Support for both 8-bit and 16-bit samples.
- combined with 6-bit or 8-bit volume.

I'm interested in your educated opinion, whether it makes really sense to increase the number of supported channels over 4.

A few opinions that we had:

a) The original Amiga could have a sound at left or right.
If you wanted to have a sound in the center both left and right then you needed to play it in two channels.
Having a center channel would be nice addition.

b) Octamed showed that its relative cheap to virtuelle increase the number of channels by mixing channels with the CPU. If you for example play a MP3 in a game on the natami then it will use 2 channels (1 left / 1 right) - This would leave you two free channels for effects. The CPU can mix many virtual channels into those in no time at all.
In less time then decoding a mp3 you can probably mix 1 dozend extra channels - So having extra HW audio channels might be important at all.


If you have experience in creating music it would be nice if you could add your opinion.

Cheers
Gunnar

[Piru]

- The DMA of two channels could be combined to read both the sample and the volume values in for one channel.
- Doing this Paula could DMA create 2 channels with 14 bit.

This is not how the 14bit audio works.

It works by playing the high 8bits with full volume, and the lower bits with volume 1 on the other channel.

Octamed showed that its relative cheap to virtuelle increase the number of channels by mixing channels with the CPU.

Actually octamed 8-channel mode was quite horrible (lots of limitations) and very CPU hungry. AFAIK it didn't use similar channel mixing to sp3m and AHI.

Whatever you do, preferably totally separate the new modes from the old audio registers. The best solution would be to allow old and new audio to co-exist, this way you can have old apps using audio.device or direct hw register banging after allocating the channels, and new apps using the high definition audio thru AHI. AHI supports 24- and 32-bit precision with 7+1 channels.

[bloodline]

Ideally I would want at least 4 (or better 6) physical audio outputs. Which would allow me to route audio in a studio environment... or could be configured as left and right for standard desktop work, or as multichannel surround sound for entertainment.

Each physical output would require it's own channel... you wouldn't want 8 or 16bit support, 24bit is al that is required.

From a hardware point of view, you would probably really want a small "DSP like" processor and a bunch of SigmaDelta DACs... that would be the simplest way.

[riftcon]

I'm very interested in the NatAmi, but have been wondering why the new audio capabilities didn't seem to be upgraded much. So I'm glad you ask us

I've made music for my own enjoyment and programmed some players, including software mixing. I'm not sure I agree that mixing channels is relatively cheap. It quickly gets expensive if you were to play a 32 channel mod at 44.1 kHz. I worry a bit for the '060 even if it is 90 MHz.

Some things I've always missed in the Paula:

* A panning register so channels could be moved from left to right. Much like your center channel idea, but configurable by software. For instance a signed value from -128 (left) to 128 (right) per channel would be a VERY nice addition. .mod's sound SO much better in headphones when the channels are moved away from the extreme left and right position. It also opens up for some great effects in a tracker.

* 4 channels IS a bit limited, often you fight the tracker and end up having to cut off notes. I would definitely prefer 8.  Some might want more, but I'd be happy with 8.

These two fairly simple additions to your existing design would make me very happy, it would be a pretty damn good sound card. Still not as advanced as say a Gravis Ultrasound, but still miles better and more useful than the original.

[riftcon]

Oh! And another really annoying thing about the Paula ...

This I would consider essential - some kind of strobe register to force it to load the location and length registers, so you can set up the loop location and length quickly, without having to set up a timer! Man, is that annoying...

EDIT: Or simply guarantee that the internal location and length registers are loaded as soon as DMA is started....

EIDT: And you may want to think about increasing the size of the length registers. If people start using high quality 16 bit samples 128k would quickly get pretty small.

[spihunter]

These days a pro musician or even someone recording a demo would need more capabilities then a 24bit Super Paula could provide.

I think it would be great for games and regular Amiga audio output though. It would be a long needed upgrade.

I think your specs are pretty right on for regular users.

for high end users we would really need some kind of drivers (AHI or not) for pro sound stuff like the Firewire/USB interfaces or even things like the M-Audio Delta 10/10 add on card style.

[biggun]

Actually octamed 8-channel mode was ... very CPU hungry.

Yes, octamed was CPU hungry on a A500.
Of course the memory bandwidth of the old 68000 and in general form the CPU to the AMIGA Chipmem was a real limiting factor even on AGA.

But the Natami with 68060 will have no problem at all, to mix 16 or more channels.

You have to mind that the NATAMI 060 is not only running at 90 MHz and that the Fastmen is many times faster than the AMIGA fastmem was, and most important that the bus between CPU and Chipmem is many many many times faster than it was on classic AMIGAs.

In theory you could create a DMA channel on the NATAMI (like special blitter mode) that can mix sources. But as the CPU could mix for free it probably not worth doing.

Even a 48KHz sound with 16Bit samples is only 94 KB per second. If you have 16 channels this is 1.4 MB sample data to mix per second. That just about 1% of the memory bandwidth of the Natami 060, so really no problem.

[biggun]

Hi Riftcon,

Thanks for your input

* A panning register so channels could be moved from left to right.

Valuable point, thanks.
How much resolution of the RIGHT/LEFT gradition is really needed?
It it needed to have a fine graine of 256 values or
would a simpler right/left position of something like (0%, 25%, 50%, 75%, 100%) be enough too?

* 4 channels IS a bit limited.I would definitely prefer 8

Thanks, noted.

[Piru]

The point I was trying to make: Octamed is particularly bad example. sp3m was the first app to really show what can be done with real channel mixing.

[biggun]

spihunter wrote:
These days a pro musician or even someone recording a demo would need more capabilities then a 24bit Super Paula could provide.

Oh, the Natami is NOT designed for pro musicians at all.
Sorry if my question sounded like this.

The question was to ask experienced music developers, as what in their opinion are the minimum requirements for good sound in a Amiga home computer.

We all agree that CD is good quality sound, and for perfect CD player quality all you need is 2 Channels with 16 bit samples each.

So 4 channels with 24bit quality is a very good start, I think.
I acknowledge that HW support for having channels in between left and right, and a few channels more will help creating AMIGA mods with zero CPU useage.

[riftcon]

biggun wrote:
How much resolution of the RIGHT/LEFT gradition is really needed?
It it needed to have a fine graine of 256 values or
would a simpler right/left position of something like (0%, 25%, 50%, 75%, 100%) be enough too?

Hmm, I think 5 bits of precision would be good enough. It would be nice to be able to pan a playing sound from left to right and back in not all too discrete steps. At least not too audible. I guess 4 bits MIGHT be enough, but slow panning might suffer.

It would also be great for positional sound in games.

EDIT: I just looked it up, the Gravis Ultrasound got away with 4 bits (unsigned, 0-15) and that worked just fine in trackers on the PC. So I think 4 bits would be fine.

[biggun]

riftcon wrote:

Hmm, I think 5 bits of precision would be good enough. It would be nice to be able to pan a playing sound from left to right and back in not all too discrete steps. At least not too audible. I guess 4 bits MIGHT be enough, but slow panning might suffer.

It would also be great for positional sound in games.

EDIT: I just looked it up, the Gravis Ultrasound got away with 4 bits (unsigned, 0-15) and that worked just fine in trackers on the PC. So I think 4 bits would be fine.

Yes, I think one of the first AMIGA games doing this
panning of sounds from LEFT to RIGHT and back was Archon.

They did this by playing the same sample on one channel on each side and alter the volume to get this effect.

Actually the HW needs to do about the same work for panning channels.
For each channel that can be panned, the HW will have to mix two channels - One to the right and one to the left.
In other words for the HW supporting one panning channel
needs as much HW mixer resources as two non panning channels.

[riftcon]

Actually the HW needs to do about the same work for panning channels.
For each channel that can be panned, the HW will have to mix two channels - One to the right and one to the left.
In other words for the HW supporting one panning channel
needs as much HW mixer resources as two non panning channels.

Hmm fair enough, I guess the only thing that would be faster is DMA, it would only have to fetch half as much data if it had a panning register.

Since the hardware already has some channel bundling features, as you also mentioned in the original post, what about a feature that would enable panning on a channel, but disabling another channel in the process?

For instance, it's already possible to use channel 0 to modulate channel 1, perhaps it could also be possible to disable channel 0 and get a panning register for channel 1?

But in this case I would probably like to have 16 raw channels

[TheDaddy]

This sounds (no pun intended) great Gunnar.

I would say post this on amigaworld.net too to increase your chances of feedback from expert Amiga musicians. :-)

[riftcon]

Oh I see now why you suggested 100%, 50% etc. That's obviously very fast to implement in hardware.

It would definitely make a big improvement, and musicians would still be able to make some much better stereo mixes.

If you could set a mode on, say, a left channel to be either 100% left, 50% left or %0 left (center), that would make for some much better sounding music as well! Even better if you can also move it to the right (that would require 5 panning settings per channel) so musicians don't have to think about which channel they use, but can simply set the panning in the instrument.

Yes. That would be pretty good actually. Eight of those channels, people who need better precision or stereo sweeps can do their own manual panning using two channels and volume.