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 According
to Apple, the applications below, to some extent, take advantage
of the Velocity
Engine (AltiVec Instructions) of the G4 processor. So you
should see some performance improvement running these applications
if you have a G4 machine. How much improvement depends on
what parts of the application have been written to utilize
the Velocity Engine. The AltiVec instruction set was developed
primarily to speed up multimedia and graphics performance.
Please see the note below
from Glenn Fisher of Apple Performance Product Marketing for
more detailed information on the benefits and limitations
of the G4's Velocity Engine. New AltiVec savvy applications
will be added to this list as we become aware of them.
Company and Applications (Apple's official list)
Additional Programs Accelerated For The G4
- BIAS
- Peak 2.10-TDM (Digital audio editing program)
- BIAS
- Peak 2.10 (Digital audio editing program)
- Bitheadz,
Inc. Phrazer (Real time audio loop sequencer)
- Bitheadz,
Inc. Retro AS-1 version 2.0 (Virtual analog synthesizer)
- Bitheadz,
Inc. Unity DS-1 version 2.0 (Real Time Digital Sampler)
- Cubase
VST/24
- Emagic
- Logic Audio 4.1 (synthesis of digital audio recording,
digital signal processing, MIDI sequencing, and notation)
- Proteron,
LLC N2MP3-1.5b3 (MP3 encoder)
- Quadmation
PlayerPRO 5.4 G4 (MOD/MIDI file tracker, composer and player)
- Terra
Soft Solutions Black Lab Linux (Workstations and Parallel
Computing Systems)
- Terran
Interactive, Inc. - Media Cleaner Pro 4.0.2 ( digital
media compression)
- Terran
Interactive, Inc. - Media Cleaner Power Suite 4.0.2
(QuickTime Prep)
And a note from the MotherShip:
MSZ : Is there a limit to what the AltiVec instructions
can accelerate? In other words could someone rewrite an application
to make all of it AltiVec savvy or can only certain portions
of an application be accelerated? If only certain parts can
be accelerated what is this limited to.
GF: Yes and yes. AltiVec can only provide acceleration
based on it's ability to handle complex instructions and up
to 4 words of data at a time; theoretically, if you were able
to parallelize all your data, and it was all half-word size,
you would get 8x [performance]. AltiVec also has a few instructions
that essentially do two instructions in one cycle, so you
can theoretically get 2 instructions per cycle speed up over
non-AltiVec code. However, this assumes your code can be rewritten
to take advantage of AltiVec. Many things can't. AltiVec was
designed to speed up multimedia-type operations, such as transparency,
en- and de-coding, graphics operations, 3D, etc. What deveopers
generally find is they can accelerate the part of their code
that does these things anywhere from 1.5 to 16x. But there's
a lot of 'overhead' code that can't be accelerated, so the
final acceleration ends up being substantially less. For example,
reading or writing files to disk cannot be accelerated--it's
dependent on the file system and disk performance.
Glenn Fisher
Performance Product Marketing Apple Computer
MSZ writes: We are doing some benchmarking using
Cinema 4D running on machines upgraded with G4s. Our understanding
is that Cinema is AltiVec savvy, however we are not seeing
any improvement over a similarly clocked G3. We are using
3 of the sample files and batch rendering them. What parts
of Cinema are accelerated for the G4? Can you offer us any
advice on how to gauge the performance of the G4 when using
your product?
Maxon Computer: Yes, XL6 is optimized for the
use of the velocity engine of the G4 processor. However, if
you try to compare XL6 on a G3 and a G4 at same clockspeed,
you might get different results, ranging from no acceleration
to up to 50% faster rendering.
Why? The velocity engine is mainly designed
to speed up certain mathematical functions, which are mostly
designed for speeding up playing back video, encoding and
decoding MPEG (DVD video, MP3), and also for game acceleration.
All these tasks require only a limited accurancy of 64 Bit.
A raytracer like CINEMA 4D needs a much higher precision and
therefore calculates mostly with 256 Bit accurancy. The velocity
engine is unfortunately no help here. But there are certain
areas in the software, which donĪt need this high precision,
where 64 Bit calculation is enough (e.g. the noise in lights
and some other things).
It depends very much on what you have inside
your test scene. The size of the rendered image, the size
and format of the textures, models, if your objects are parametric
or polygonized, and lots more have an influence on the amount
of acceleration.
These behaviors and limitations of the Velocity
Engine are confirmed by Apple's developer support
Paul Babb, Maxon Computer, Inc
Additional Resources:
For more information visit our G4 information Page
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