New A-EON Music Card for Classic Amigas

[spirantho]

I doubt you'd see any difference, to be honest - the Zorro II bus is about the same speed as Chip RAM (i.e. not fast).
Please remember that the Prisma is a different beast entirely to Paula. Paula plays sound samples but has no concept of streaming. Prisma plays streams but has no concept of sound samples (per se - but you can stream a sample).

The AHI driver will at best be something that might come in handy in certain circumstances, it is not (and is not designed to be) a replacement for Paula or any other sound card that requires use of a lot of samples.

[spirantho]

A sample is really just a very short stream.

The real difference is in buffering - a sample would be loaded entirely into memory and the the sound chip (e.g. Paula) is instructed to playback memory starting from its address and then stopping at the end.
Streaming would be where - in the case of a sound chip like Paula - you would keep looping the data and changing the data in the buffer. With the Prisma, it just keeps on decoding and playing whatever we send to it. We can play samples on the Prisma in the same way as with Paula - by telling it to decode the contents of the buffer - but only two channels are available. We can't tell Prisma to play more than two sounds at once, in other words, and one would be in the left speaker, the other in the right.
With software mixing this isn't a problem, of course - but then speed becomes a factor as software mixing can be slow.

What it comes down to is this:
Sound samples - should be very quick to play with low latency (point Paula to the memory and let it do its thing). Prisma can not do this easily.
Music streams (or mixed audio) - Paula can't do this easily - it requires juggling a buffer to keep the data going. Prisma can do this easily - just keep feeding it data.

[spirantho]

I agree with you right up to the last few statements.

This card is a music player. NOT a retargetable audio sound card. The idea is to allow people to play music on their Amigas of whatever spec. There is the useful side-effect that people like Novacoder can use the Prisma to play backing music on games which have a compressed audio stream. Paula should still be used for sound effects, which is what it's good at (after all, an 8-bit explosion sounds pretty similar to a 16-bit explosion) and why the Prisma mixes in Paula audio with the outputted music stream

If you're not looking for a card that can play compressed audio in CD-quality, but are looking for a full sound-card then this card is not for you.
But if you are looking for a card that can play just about any music track on your Amiga, and (with help from people like Novacoder) able to play games with a full soundtrack like ScummVM, then this is what you are looking for.

For what it's worth, this will make it MUCH easier for bedroom coders to play back compressed audio soundtracks while using audio device (Paula) for spot effects. A simple call to Prisma_PlayFile() is all that's needed - can't get much simpler than that.

The planned AHI driver does not mean the card has the same qualities as a full sound card - it just means a way of getting CD-quality audio out of a normal Amiga - maybe useful with things like emulators where it's just a sound stream but is uncompressed.

[spirantho]

I'm not sure people do expect a considerable boost in anything except compressed audio streams, do they? I'm not sure why'd they think that, to be honest.
Generally speaking I think Paula is quite fast enough to do spot effects itself - it's something the Amiga has always been able to do well. What the Amiga has never been able to do is to decode high-quality music, and that's what the Prisma does.

From the press-release:

The Prisma Megamix is a dual-use card which can be connected to either the Zorro II or a Clockport and incorporates a VS1063 DSP chip which can play and encode MP2, MP3, WMA, OGG, LC-AAC, HE-AAC, FLAC, IMA, WAV PCM and many other sound formats  making it ideal for hi-fi audio playback and streaming applications.

I'm not sure why people would think it would do anything other than stream audio? We've always said the planned AHI driver will be minimal because this is a decoder card that happens to do PCM.

Note I'm not trying to be critical here - I just want to know where this misunderstanding has come from as I don't want people to buy the card thinking it's going to somehow speed up old software!

[spirantho]

yes, but then if you bother to rewrite every sound effect call to paula, and convert every sample to amiga format you end up with a port, that will run as well on amiga hardware without the card in question. perhaps except the background music, but thats the whole difference.

That IS the difference, exactly. It's not designed to help with anything else.

i not trying to be critical either, the whole point is i agree exactly on this statement with you, and this is the whole point of my posting.

That's good, this is the whole point of my replying.

It's very difficult to get across exactly what a card can do when we ourselves don't know what it can do as the software is still being written. The best I can do is try to field as many questions as I can when people have them.

I really don't want us to sell Prisma cards to people expecting a full sound-card like a Delfina or Prelude - that's exactly what I'm trying to avoid. But to many people, being able to do things like have music in their games is part of the experience - especially on some games like Monkey Island where the music is awesome!

I also don't want to sell the Prisma short, though - it's a nice piece of kit. I know this because my A1200 is kicking out a "Yes" album right now (using my NAS over wifi to serve the 200Kbps OGG) as I write this post. And that's a good thing.

[spirantho]

@wawrzon

don't worry, it's very easy - just call OpenLibrary on prisma.library and if it fails, then don't play any streamed audio. No reason for it to be complicated.

Edit:
@Novacoder

Thanks for the kind words.. it means a lot to hear that it's working and doing what you want (it's not like I'm getting rich off this. ).

[spirantho]

Not sure about Toccata emulation - depends on how difficult it is to add and how useful it would be.

It can play 320kbps mp3, yes.

[spirantho]

OGG Vorbis playing is much more important to me.
But yes, I can't stress enough, the card is made for playing compressed audio streams above all else.

[spirantho]

It's a nice idea, but the A1200 wouldn't be enough, I don't think. The ClockPort would be out, for sure (far too slow) maybe a Zorro-III card could send the data fast enough, I'm not sure - Zorro-II would be enough for smaller videos.
It's a possibility, after all the CD32 had an FMV cartridge, but I'm not sure how easy or worthwhile it'd be given it'd be limited by the bus bandwidth.

[spirantho]

Believe me, we've thought about it.
We're still looking at doing an AHI driver for the card, but this is secondary to the primary purpose, so will come later.

The problem is that when we mentioned AHI, people expected it to be a fully retargetable audio card like a Prelude or a Toccata - it's not. The VS1063a has a tiny buffer on it, so it's not suitable for anything other than streamed music really - i.e. what it's designed for. In fact, if we do an AHI driver, it will primarily be for Octamed and things like that!

[spirantho]

If the author of Digibooster 3 wants to use the Prisma.library directly, I'm more than happy to help....

[spirantho]

It works on the clockport the same as Zorro... but the bandwidth is much less so you're better off with Zorro if at all possible!

[spirantho]

Is it possible to playback MP3 at 320 kps with a 030@25 MHz?

I've played 320Kbps MP3 on an unexpanded 68000-based Amiga 1500.... so yes.

[spirantho]

The Prisma is not a retargetable audio card, never has been. It's a streamed audio card. We do want to make an AHI driver but it will never be a very good one because it's just not designed for that.
What it is good for is streaming compressed audio, which is much more than just MP3.
Many games use OGG Vorbis, for instance, which is also what I keep my music collection in. With this card you can run things like Odamex with full-quality stereo music as played by very expensive synth equipment, because people have ripped the audio from their expensive setups and supplied it as an OGG for others to enjoy.
I know this because I've done it. It's cool!

I'd like to get Open Transport Tycoon updated with Prisma support, too. That'd be nice. It's just a matter of finding the time for me though.

[spirantho]

That's like asking if a Video Toaster is better than a Cybervision 64.

It is a streaming audio card, not a general purpose sound card like the Delfina.

[spirantho]

The chip in the Prisma is well documented, so it's quite easy to use. I'm more than happy to help provide pointers etc. for using it.
You could make your own interrupt routine without the OS and spool from RAM very easily.
I wouldn't recommend killing the system if you can help it though!