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The Successor to AC'97: Intel High Definition Audio
An anonymous reader writes "A few days back Intel announced the name to
its previously dubbed 'Azalia' next-generation audio specification due out by midyear, under royalty-free license terms. The
Intel High Definition Audio solution will have increased bandwidth that allows for 192 kHz, 32-bit, multi-channel audio and uses
Dolby Pro Logic IIx technology 'which delivers the most natural, seamless and immersing 7.1 surround listening experience from any native 2-channel source'. The architecture is designed on the same cost-sensitive principles as
AC'97 and will allow for improved audio usage and stability."
The very first thing I thought when I saw the article itself was, "Please don't let this be as bad as AC'97."
Don't get me wrong, AC97 is cheap, but it really dragged on the CPUs of the timeframe it came out. This one looks like it might be a shot at the Creative Labs end of the market, but with cheaper components (meaning most likely CPU-based)
I'm sure it'll be on pretty much every board before too long-- well, the non-nForce ones, anyway.
On its face this is a great announcement, but we must have all the usual concerns. Will it work in Linux? Are the hardware API's going to be published, so someone can write Linux drivers? Or is this going to be the next Centrino, needlessly obfuscated to give Intel's friends in Redmond yet another unfair advantage?
I'm also concerned that a new audio hardware API may introduce way too many opportunities for things like Digital Restrictions Management. Long term, doing that is of course futile because someone will find a way around it, but that doesn't stop some hardware makers from setting out the legal minefield anyway.
It's a sad state of affairs when politics and litigation are at the forefront of geeks' minds when technology ought to be.
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32-bit audio at 192kbps? Why not just stick with 24bit at 96kbps - it is good enough for most studios. And actually 16-bit at 44.1kbps is the most that these old ears are gonna hear anyway - if even that well after sitting front for Jimi Hendrix.
It depends on how nice intel is feeling. Royalty free doesn't mean that intel doesn't control it. Royalty free only implies free as in beer, not free as in speech.
At least they are changing an old standard that has had mixed issues for several years. New input on old (possibly failed in some aspects) standards is always good for sales.
If only there were some way to have a digital output from the computer, and do the D/A conversion in a dedicated box.
The Intel High Definition Audio solution will have increased bandwidth that allows for 192 kHz,
...
192 kilo-Hertz? that's more longwave radio than audio. Hell, it's like 5 times the frequency of ultrasounds. Who are they kidding? This smells of marketting bull, or deceptive commercial practices targetted at trendy audio posers
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Even better would be if turning it off in the BIOS meant that the OS actually ignored it.
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I think you're deluding yourself. Audiophiles make a lot of claims that they can hear certain things, but they never test their own claims using double-blind studies in which the other variables are all controlled for.
I teach a physics lab class, and in one of the labs, I have students test their own hearing, to see the highest and lowest frequencie they can hear. There's some individual variation, but basically the top end of everyone's range comes out to be no less than 10 kHz, and no more than 20 kHz. I have never had a single student who could hear frequencies above 20 kHz.
The 44 kHz (IIRC) sampling frequency of a CD means that you can actually record signals with frequencies as high has 22 kHz (half the sampling frequency -- that's a methematical theorem about the discrete Fourier transform). The reason they designed CD audio around that figure was exactly because of the limits of human hearing.
Even if there was a hypothetical human who could hear 30 kHz, there would be many other things preventing it from being useful musically. For instance, your tweeters most likely can't respond well to those frequencies. Furthermore, the music might sound worse to such a person if the 30 kHz stuff was left in. The musician couldn't hear it, and therefore couldn't adjust his tone to make it sound good. The audio engineer also couldn't hear it, and therefore couldn't judge whether it sounded good or not.
Another practical issue is that distortion will always introduce high-frequency harmonics, so that even if you could hear those frequencies, a lot of what you were hearing would probably be spurious stuff coming from distortion.
People who really want to hear good stereo sound should spend their effort on the two things that will make a lot of difference: (1) getting good speakers, and (2) working on the acoustics of the room, the placement of the speakers in the room, and the placement of their own head in the room. Note that all the stuff under #2 is free or cheap. The audio industry would rather have you waste your money on stuff that's expensive, which is why they promote expensive, superstitious ways of improving sound, such as gold monster cable.
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You're right... but keep in mind that most of the motherboards out there that give out lousy sound from onboard are due to poor layout from the manufacturers... who giving poor layouts because want to save money and physical space on the motherboard, at the expense of analog components like sound...
more bits and more kHz are useless for onboard until you clean up the analog paths to the jack, and properly isolate the codecs on the motherboards using ground moats. Nothing worse then a company that routes a processor +12V feed trace right under the analog side of the codec... or worse, a noisy signal like PS/2 or NIC.
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In any event, if Intel are letting groups take their spec and implement it in hardware that's meant to be sold for profit... It doesn't get much freer than that. "Free as in speech" doesn't mean you have to give away the farm. You're allowed to keep certain rights for yourself, and make certain restrictions on use, just like open source software does. (And just like there are for free speech, in fact.)
Centrino's wireless Ethernet controller is roughly the WiFi equivalent of a WinModem. Some of the components that are traditionally done in hardware (I'd guess the same stuff as in WinModems, like the DSP work, though I don't know the exact extent of the "softwarization") are done in software. Intel is not holding back on Linux support to secretly help out Microsoft -- I agree with you there. They're just in the same position as the WinModem vendors. If they supply their product's crown jewels -- open source the software that does a lot of the heavy lifting in their hardware product -- they've funded the R&D for what will be promptly snapped up by competitors and produced more cheaply.
So, you are right that there is no plot to help out Microsoft, but the grandparent is right that Intel may be cagey about supporting a platform where users are rabid about having source (and much of the architecture works less reliably without source).
Frankly, I'm frusterated with the whole laptop situation, and I wish, wish, wish that laptop vendors would make some critical mistake in the price wars and accidently commoditize their product, with standard components and form factors, so that things can be built and swapped out a la desktops.
May we never see th
Yeah, it's terrible how nVidia MADE 3Dfx screw up their entire distribution channels, how they made them buy out STB and try to become a card manufacturer. Absolute horrible how they made 3Dfx deliver all their products a year late (or more) and missing much-needed features. And it was especially bad how nVidia made 3Dfx release crappy drivers (or no drivers) for so long.
Face it, 3Dfx killed themselves, nVidia just moved in to pick up the slack. Even if the whole lawsuit between the companies had gone in 3Dfx's favor it's unlikely that they would have managed to survive long enough to see the results of it. A combination of bad decisions and products that were a day late and a dollar short (but still expensive) killed them, not nVidia.
It is still onboard sound
Not necessarily. The specification can be used for PCI cards as well, and in fact AC97 is used on some lower-end audio cards. It's more of a specification for minimum supported features and other specs.
The fact that it is on-board in itself doesn't mean it is bad. It's all in the implementation. With proper design techniques (ground-loop isolation, etc) you can get quite a good S/N ratio. It doesn't need "separation from the motherboard", rather, it needs a buffered power bus, separate audio and digital grounds, etc.
The bottom line is, you get what you pay for. If you spend $100 for a motherboard with onboard sound, video, nic, modem, etc... you're likely to get cheap versions of each. If you spend $130 on a PCI sound card, you'll probably get really good specs, whether it is based on AC-97, this new spec, or its own details.
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I'm guessing you don't work in the industry... it's not only possible, but it's been done on many designs...
Codec construction is important, for example two major suppliers from Taiwan: C-Media and Realtek, are both pretty much crap even on their high end parts... they've traded features and low BOM cost for audio quality...
Other codec supplies, like Analog Devices & Sigmatel (or even Wolfson, Phillips, etc) have put audio quality as a priority to feature sets.
Unfortunately if Realtek rolls out some new feature then the others need to follow or be left behind.
Using ground layers properly, moats and keeping traces near the edge of the board... or even better, making sure you keep the codec as physically close to the jacks as possible, will yield very good results easily rivaling your average sound card.
Let's also keep in mind that an AC'97 or "HD-Audio/Azalia" codec goes for between $0.50 and $1.25...
Where-as a typical SoundBlaster will go from $50-200... they're able to use a lot higher grade support components, and since they are on a PCI card they're able better isolate from the rest of the motherboard (which speaks to your point...)
As for digital out...
Many motherboard manufacturers are finding that the masses are demanding SPDIF (digital) output from onboard sound, it's been available for the past several years from AC'97 vendors, even on most of the low end codecs, but adding the TOS (or even RCA) jacks cost too much in BOM and board real estate (surprise, surprise)...
I think the next big requirement from users will be that SPDIF provide an AC3/DTS signal for all 4/6/8 channel audio. I'm surprised that this wasn't a requirement for Azalia, but we'll see what happens in the near future... After all, AC'97 is currently at version 2.3, there's room for change...
Currently nearly all (even the $200 SB Audigy2) provide only PCM (2-ch) when playing non-DVD audio (when playing DVD they will all pass the AC3/DTS signal out, but they do not generate their own based on a multi-channel game or sound file).
This is mainly due to the licensing fees from Dolby to encode AC3/DTS signals, and partly due to the processing overhead that would be required for implementation in soft-audio.
The exception to this are boards equipped with the nVidia nForce2 audio, they build a DSP into the southbridge(ICH) that encodes AC3 out of any 4/6-ch source being played.
But if you use a 40.00001 kHz and a brick wall low pass filter at 20 kHz you will get the original wave.
The only real reason to higher than 2X the audible range is that it is difficult to make brick wall filters. In theory a "muffled trapetzoid will still represent the original wave correctly. Nyquist was pretty clear about this. =).
Linear PCM is just such a waste of space above 44kHz sampling frequency. Everytime you double the sampling frequency you double the amount of data but you only get one octave more information. So if the signal is music, frequency shouldnt be linear. Wavelets for instance are much more efficient at storing data but much more complex to implement. 192x32 is just a brute force way of saying: I cant afford to make decent filters.
Your "power-calculation" just shows that you have never taken a signal processing class in your entire life. But thats ok, those classes are hard.
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