New A-EON Music Card for Classic Amigas

[psxphill]

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).

Can you define what you mean by sample and stream.

[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.

[skolman]

First, to get good sound quality we would need to replace the AHI, read a Interview: http://amiga-news.de/en/news/AN-2014-03-00064-EN.html

[wawrzon]

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.

thats finnally spelled out as i suspected.

With software mixing this isn't a problem, of course - but then speed becomes a factor as software mixing can be slow.

okay, so with software mixing the card practically loses its all advantage against the bare system. the speed and the cpu load would immediatly become the same problem as it is without the card.

few years ago i ported or attempted to port different sdl games to amiga and so noticed that the sound is usually necessary to be turned off as a whole in order to make it at least thinkable to port. the load of decoding sound alone was taking almost the whole bandwidth of the system even with a 060. now if we imagine such a typical game, its audio consist usually of an underlying soundtrack plus a great number of event triggered sound effects that may well happen at the same time or overleap.

all in all even if we have just stereo soundtrack to decode and a single layer of sound effect samples it seems the card becomes unusable to conveniently cope with that task.

and i very much doubt that when porting game your regular bedroom coder will be able to leave the soudtrack as compressed audio while converting the sound effects to be played by paula, as it has never happened till now to my knowledge.

so, im sorry, looks like this card is useless except for playing back mp3s.

[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.

[wawrzon]

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.

but thats exactly the problem your card will not improve upon. even without background music, which is easy to get along without anyway, be via it paula or another ahi device the sound effects decoding will likely create a load that is unbearable for an amiga system one way or another.

my point is exactly that, this card is hyped as a (multipurpose) "sound card" able to play compressed formats, and people expect considerable boost in general audio playback, games and other applications, while as you wrote its is good to playback one stereo soundtrack at a time.

[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!

[wawrzon]

@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.

as you see people are asking questions like if this card would assist with their music software (be it hd-rec, or some tracker i dont know) to play multiple compressed tracks (i assume). then the people wonder their games would run faster with it or will there be games with more sound effects and so on. this is not entirely clear to everybody, which you may not realize being yourself involved, and to be honest, you were a little vague about this, probably in order not to turn people off in advance.

just to observe that the title of this thread suggests a general purpose sound card, and as for the press release it suggests that it can play compressed formats, not mentioning that it is restricted to just one hardware accelerated stereo stream/sample at a time.

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.

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.

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!

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.

[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.

[wawrzon]

thanks, and keep us posted on unexpected achievements.

[NovaCoder]

I did a quick update to my upcoming Duke Nukem port tonight to add Prisma support.  After tracking down some really high quality OGG files of the game's original music it was really easy to do.   I've only given it a quick test but it doesn't appear to be adding a noticeable load on the CPU and it sounds fantastic.  

Spirantho has done a really good job with the library

I'm currently waiting for the video to be uploaded.....


[youtube]UlZLK3CO1Fk[/youtube]

[wawrzon]

@nova
do you think its possible to keep prisma detection and support within universal executable?

why im asking this is because of the versions mess on aminet where every cpu gets its own dedicated optimized executable. this is in many cases already a task for itself to find the right one. i think we should push towards plug and play philosophy where possible, too much thinkering puts the not so hardcore audience off.

[NovaCoder]

@nova
do you think its possible to keep prisma detection and support within universal executable?

why im asking this is because of the versions mess on aminet where every cpu gets its own dedicated optimized executable. this is in many cases already a task for itself to find the right one. i think we should push towards plug and play philosophy where possible, too much thinkering puts the not so hardcore audience off.

It uses a library which means it will be upgradeable as long as the interface methods don't change.

[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. ).

[amigakit]

@novacoder

Awesome news: cant wait to view your video and try your port  Thanks for integrating Prisma with your port.

@spirantho
Thank you for your hard work on the prisma.library - much appreciated

[wawrzon]

@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.

perfect. thats what i mean!