Amiga soundcard Prelude vs Prisma?

[spirantho]

For full AHI I would recommend the Prelude.
However, for compressed audio (and games which use compressed audio for music streams), the Prisma is probably the way to go.

[spirantho]

The aim is to give the Prisma a limited AHI device. It will always be limited because it's not really a sound card, it just happens to support uncompressed audio.
The software is centred around prisma.library - a library of easy-to-use functions such as "PlayFile()" and "PlayMemory()" - I like to keep things as simple to use as possible for the programmer.
There is also an MHI device for AmigaAMP, though AmigaAMP only supports MP3 files. Any other software using MHI should therefore be able to use it. Hopefully they'll one day add support for parsing OGGs and FLACs etc. too, but we're going to release it with a playing GUI in the meantime.

As there's no real standard apart from MHI, we can't really offer compatibility with other hardware decoder cards for apps without MHI (making an emulation library of the Prelude etc. may be possible but it would take a while and I'm not certain it's worth it).

Anything you're not sure about specifically? Happy to help.

[spirantho]

Thanks for the great description!

I'm looking to primarily use this in a HIFI system for listening to audio.  

How will the quality compare with a Prelude for that?  The chip will be faster than the Mpegit, but will the quality output to a HIFI be comparable?

Then you want the Prisma.  And don't use MP3s if you can help it, use OGG or FLAC... better quality. If you really want to use MP3s though, you can use Mpeg 2.5, and you can use the higher bitrates.
Your HiFi does have S/PDIF for digital audio, right...? You don't need it, but it will help with quality.

[spirantho]

Basically, yes. The Prisma is a decoder really, it just happens to be able to play spot effects - but only one per channel at a time. AHI does support software mixing, but it will be slower.

What you can't do on the Prisma is play a music in the background and then play spot effects on the same channel - so you're limited to using another sound source like Paula for spot effects (though you don't really need CD-quality blood splattering sounds or whatever )

The Prisma is first and foremost a music card - the real advantage I reckon is that it allows us to use really good quality streams on a humble not-very-expanded Amiga, even a 68000-based one. I can't think of any other way to play heavily compressed lossless or high quality audio on a low-spec machine, and I think even a faster 68K Amiga would struggle normally with the high bitrate MP3/OGG/FLAC streams.

I can't say what the quality is like compared to a Prelude because I don't have one, but I do know it sounds good and the background noise level is notably less than my PC.
For what it's worth I do tend to notice when something doesn't sound good (I'm the sort of person who spends far too much on his vinyl ), and it does sound pretty fine to my ears.
I have high hopes (and I don't just mean Bruce Springsteen's latest album, but that may be played too) for FLACs played through the S/PDIF digital output .

[spirantho]

It does have recording ability, but only from line-in or mic in.

I'm not sure about mpeg.device - maybe later in its lifecycle.... but if it was that suitable they wouldn't have invented the MHI interface. I may look into it in future.

The real advantage is the support for so many formats, I reckon.

[spirantho]

I don't think the Prisma would be suitable for mixing, I'm afraid. You need a proper dedicated DSP rather than a decoder for that - and I think the latency would be too high on the Prisma if you want things to mix properly. To mix two tracks you'd have to "decode" a pre-mixed WAV.

[spirantho]

What gives you that impression? I've already played high bitrate OGGs and FLACs on my unexpanded A1500

[spirantho]

Guess I have to go back to school and learn how to read..

You mentioned parsing and I read playing....

What software are you using to play OGGs and FLACs?

My little CLI program called PrismaPlay. It does the trick.

[spirantho]

There will be a GUI, yes - for testing it's easier to use a CLI program though.

We do intend to be able to have more than one Prisma card. Probably the first version won't support it but we'll see how many people want to run more than one at once... it's probably not terribly useful though as most people only listen to one music track at a time I suppose it could be useful for DJing, though, to have one fade into the other....