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avantgarde2
Član broj: 252533
Poruke: 13
91.148.86.*
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Googlovao sam malo i istrazivao na ovu temu, nasao ovaj text i dosao do sledeceg zakljucka.
Samo da pojasnim:
Envy24 cip koji koristi M-Audio Audiophile 2496
CMI8788 cip koji koristi Asus Xonar D1, DX...
CA20K1, CA20K2 cip koji koristi Creative X-Fi serija.
Citat: Originally Posted by triggerc
What part of "Audio Processing Unit" is so hard to understand? If you want to argue semantics, fine, the Envy24HT-S is host based, it doesn't count as a bonafide processor, but the CMI8788 is built from the audio processor up. I fail to see how the EMU CA20K is more of a "processor" than the CMI8788.
BTW I'm still laughing, especially at the following bolded section
Wow, I think I must relearn everything I've ever known about sound cards. They don't process the audio? I don't think I'll need a sound card anymore since it doesn't really do anything, I'm gonna have to buy X-Fis again because they ACTUALLY PROCESS THE AUDIO, unlike other sound cards. /Sarcasm
Although the CMI8788 is a really good audio chip, it's still a DSP - although highly specialized. On many older audio cards, you had a "chipset" which was a combination of a few various DSPs, DACs/ ADCs and other components - which made up a 'set' of 'chips' that processed audio signals in a specific manner.
The CMI8788, though, is a single DSP - it can carry out processing much more efficiently and faster than many DSPs can, but because it still relies heavily on the CPU and the SYS BUS, it still gets labeled as a chipset.
The CA20K1, on the other hand, is a highly specialize processing unit, that is comprised of a handful of individual components all intergrated within one singular unit - making up the whole . . . and the CA201K has no need for CPU processing, the unit handles all audio stream processing onboard - although it still needs to make use of the SYS BUS for access to DRAM (can't get around that, every expansion card does).
for a better understanding of the X-Fi architecture, and how it operates, I'll post a quote taken from techreport.com It's a lot easier to understand than what info Creative has released in the past; and TBH, the review does a better job than I right now as I'm tired and not in the mood to type a butt load of stuff to you again....
Citat: Originally Posted by
The X-Fi architecture
Before exploring where the XtremeMusic fits into the Sound Blaster Xtreme Fidelity family, let's take a moment to explore the 51-million transistor X-Fi audio chip that's at the heart of Creative's new Sound Blasters. Manufactured using 0.13-micron process technology, the chip has roughly half the number of transistors of an Athlon 64 and more than 11 times that of the Audigy, so it's quite a leap from previous generations.
The X-Fi's processing power is divided between five internal units: the sample rate converter, digital signal processor, and mixer, filter, and tank engines. Much of the X-Fi's muscle ripples through a sample rate converter (SRC) that Creative claims pushes over 7000 MIPS. The SRC is actually made up of 256 individual sample rate converters, all of which tackle sampling rate conversions in the same manner. First, the sampling rate of an incoming audio stream is doubled. Next, a poly phase Finite Impulse Response (FIR) filter is used to produce a sampling rate four times greater than the desired output sampling rate. Finally, the sampling rate is reduced by a factor of four for output. According to Creative, this process is nearly transparent, and any loss in quality during sample rate conversions is miniscule compared to the noise generated by even the best DACs available on the market. If you're not convinced, the SRC can be bypassed when it's not needed.
Although the X-Fi's sample rate converter has significantly more processing power than the rest of the chip, it's still only one of five main chip components. The next X-Fi component of interest is the Quartet DSP. Quartet, in this case, refers to the fact that the X-Fi's digital signal processor is made up of four SIMD (Single Instruction, Multiple Data) hardware threads. Each of those hardware threads has two data paths, leading Creative to describe it as TIMD, or Thread Interleaved Multiple Data. Giving each DSP thread dual data paths is a clever way to deal with audio data, which generally arrives in multiples of two. With four "stereo" hardware threads, the DSP can tackle eight data streams at once—perfect for an eight-channel sound card. As one might expect, the Quartet DSP's instruction set is audio-centric. It can handle both fixed and floating-point data types, and Creative claims that the interface is programmer friendly.
The Xi-Fi's SRC and Quartet DSP are undoubtedly the stars of the show, but the chip has several other essential components worth mentioning. More than 1200 MIPS of processing power are dedicated to the X-Fi's mixer, which handles the scaling, combining, and, of course, mixing of audio streams. The "Tank" engine handles all of the X-Fi's delay-based effects, including reverb, chorus, reflections, and inter-aural time delays, while a filtering engine dedicates a couple hundred MIPS to environment modeling, equalizers, and positional 3D audio. The X-Fi also has a transport engine that interfaces with onboard memory and an I/O bus, such as PCI. As you might expect, the chip also has an audio I/O component.
and if one still needs further proof of the CA20K1 being more of a processor . . . on an X-Fi PCB, there is typically a small flash memory module located nearby the APU. This module is used to store the APU BIOS that your SYS BIOS needs in order to be able to properly communicate with it - much similar with how modern GPUs have onboard BIOSes as well. Some X-Fi models, though, don't have the flash memory module, and instead use a standard DRAM module in it's place. On these models, if you were to run the serial number on the DRAM, they typically come back as a 2MB module......
I hope this will answer all your questions.....
EDIT=I came up with a good analogy thought id say it before i go for a class...A DSP, like the CMI8788, is still a processor, true - but it's slow and somewhat oudated, unlike a processing unit. Like how in the olden age, a CPU was just a processor, and you'd have other components - like the math co-processor - arranged nearby to the central processor. Although an Intel 80186 was still a CPU, they were rudimentary and unevolved by todays standards, relying heavily on these other, smaller processing chips to carry out tasks.
the CMI8788 is to an Intel 80286 as a CA20K1 is to an Intel Pentium 4.
Posto se u ovom slucaju sve vrti oko moci procesora zvucne i njene mogucnosti da preuzme opterecenje na svoj procesor, ova X-Fi serija zvuci kao dobar izbor + citam kako Creative nema vise problema sa drajverima itd. Podrsku za ASIO naravno ima...
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