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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