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Re: Bug#362590: FTBFS on m68k

Ingo Juergensmann schrieb:

>>I'm not sure that's really all that important? I've never used any such
>>card, but OpenAL has been working nicely for me on powerpc, amd64 and
>>i386. I suspect the real questions are
>>      * Do m68k machines typically have enough horse power for OpenAL to
>>        reasonably mix the stereo stream?
> Well, even low-horsepowered boxes like a standard A1200 can mix 4 8bit
> Channel into 2 14bit channels without many problems. (The 14bit thing
> is limited by hardware, not the processing power).

A 8Mhz system can mix four to eight voices if you use some handmade assembler hacks but will be 100% occupied with soundmixing. I doubt OpenAL is using such efficient methods for mixing.

Another problem is the volumne: The typical onboard-sound-solutions do not have the same behaviour than todays audio hardware, that is, if you mix on a modern system four times the exactly same audiosignal then you get a four times louder signal - I guess thats because they have spare bits in the final DA-logics. Do this on old legacy hardware and you end up with chopped spikes or have to reduce the volumne by downmixing the waveforms (math takes lots of cycles), therefore producing very low volumne. I remember I had to turn my volumne up nearly ten times to hear anything after mixing 16 channels on my amiga 3000 and then I nearly got an heartattack after the first "nonmixed" sound. All in all a not very desirable solution. This may differ for add-on-soundsystems though.

I would prefer a patch to the m68k-OSS-legacy-drivers inside the kernel to "accept" 16Bit-audio and "downmixing" it to the 8Bit because 8Bit-audio tends to cause trouble with recent software.

> I don't thing there's an uptodate 3D graphic card for Amigas at least
> with enough power to be usuable. There are of course some Virge3D
> based cards out there, but I don't know how well supported these are,
> because I don't own such as card.

There are some Permedia2-solutions made for Amigas and you can use nearly every PCI-card by using a PCI-daughterboard. ATI even had some Amiga-specific drivers on their homepage and I am really talking about recent hardware like Radeons.

Btw, with the PCI-Daughterboard you should be also able to use PCI-Soundcards but I have never heared of any drivers for AmigaOS or even bleeding edge tests under Linux. It is out there, should be mostly compatible on port- and register-level but nobody has done anything yet.

> I believe 3D on m68k is rather useless nowadays, but if someone knows
> better than me, please shout now! :-)

Don't expect surprising results from m68k-3D. But games like Shogo and Quake1 made good use of the Permedia and ATI-solutions and have been pretty playable.

Btw, I only knew one person with a Permedia2-solution, he has sold most of his stuff though and never would have even considered using Unix. And I have only read about other addons like the PCI-daughterboard, Zorro-Soundcards, PCI-ATI-cards and so on.

That stuff should be pretty ultrarare. Maybe you'll find five people on the planet who would like to use it with m68k-Debian. All others are happy with their legacy-sound and maybe a rough 2D-SVGA-addon based on some ancient Cirrus-Logic or S3 chipset. Or in other words: There are more important things to fix on m68k.

 Christian Brandt

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