The Mystery Of The AC97 Sound...

[Martyn]

If anyone is interested in the CPU usage of onboard/PCI audio chips you may find this interesting:

http://www6.tomshardware.com/game/20030405/index.html

This is just CPU usage tho', not audio quality.

Martyn.

The best soundcard ever for CPU usage was the original ISA Gravis Ultrasound.  ZERO CPU usage. You can't get better than that! :-D

[Floid]

mdma wrote:
For anyone having problems with SBLive/Audigy on VIA chipset motherboards, do the following.

Installing a BIOS update can't hurt, either, especially if you have a board from a vendor (EPoX :-D) that specifically addressed the issue.

Googling around for "Via PCI burst transfers" and so forth ("burst transfer bug," "KT133A PCI burst," etc) should turn up more detail on the issue.

Looks like some detail on the latency patch - and a 686B bug! - here.

[Blomberg]

MIDI support isn't a part of AC97 at all

I will not dispute that, as I don't know much about AC'97 as a standard.
I use the MIDI in (joyport thingy) of a VIA 686b with AC'97 on a daily basis, and it does the job fine for me.

My quarrel with this chip is the audio quality. When cranked up high, it creates noise. This is not a problem for 'normal' users, though, unless you do recording or are just picky with your audio  :-D
Compared to other AC'97 solutions, this is certainly one of the better ones (or maybe I was just lucky with my mobo  :-) ).

I intend to get myself a 24bit, high quality sound card at some point (for my PC), but these most often come without any MIDI functionality at all, so the VIA chip will continue its duty in that particular area, it's quite adequate.

[Floid]

Martyn wrote:
http://www6.tomshardware.com/game/20030405/index.html

That's a good example of Tom being a crackhead.

Well, not really, but it's a pragmatic review for Windows gamers, and doesn't go into the issues that actually produce the results.

As a good example, the CS4624 pulls even with the Audigy- but they're in no way comparable chips.  It just happens that they both support EAX- and both hang off the same spot on the PCI bus (meaning, no intervening PCI<->PCI bridges to further cloud the issue).  Meanwhile, the 'crappy' Realtek and C-Media don't really support 3D sound* - no surprise there; CPU load can't help but go up, as DirectSound presumably takes over the processing... or even if DirectSound doesn't handle it (no idea; not a Windows sort), the *drivers* may not have been as polished, spending more CPU time unnecessarily, when the interrupt load/etc in accessing the hardware is probably *exactly the same* for plain stereo (when the driver gets around to actually sending the data out).

--

For the resident procyonid:  Welcome to the latency issues momma warned you about... and didn't Billy tell you to buy XP if you want to play games? ;-)

For Ole-Egil:  Please tell me this is only an issue for the PowerPC/AmigaOne kernel?  Or is Linux really that bad?  :-?  My last experience with it was trying to enable an old Soundscape ISA PnP, which didn't go well, but then, I was never any good with any of the Linux kernel/driver methodologies.

--

*Okay, not sure what the deal with the C-Media is, but I imagine he's confusing the '3D space enhancement' feature - basically a hardwired 'effect' with variable gain - with some claim to EAX support.  Which is, admittedly, easy to do.  (I made that mistake with my old Crystal Sound ISA card - AOpen model-numbered their cards *backwards* vs the chipsets used, or somesuch oddity.  I got an AW37 Pro when I wanted an AW35 Pro, or the other way around... too lazy to look it up.)

Installing a BIOS update can't hurt, either, especially if you have a board from a vendor (EPoX ) that specifically addressed the issue.

I have an EPoX 8KTA3+ RAID motherboard, it's the best board i've ever owned and it's over two years old now. I'll agree with you on the BIOS upgrade too.  Also worth a mention is to make sure the soundcard is in a Bus Mastered PCI slot.

[Floid]

Blomberg wrote:

MIDI support isn't a part of AC97 at all

I will not dispute that, as I don't know much about AC'97 as a standard.
I use the MIDI in (joyport thingy) of a VIA 686b with AC'97 on a daily basis, and it does the job fine for me.

AFAIK, just about everything MIDI (except possibly 'odd ducks' like the SBLive) uses an MPU401-compatible interface.  AC97 is a standard interface for... AC97 audio (waveform data); the MPU401 was/is a MIDI UART, for transferring MIDI data (instrument selection, note triggers, etc).  I forgot that such support was built into the 686B, but yeah, there is something there.

My quarrel with this chip is the audio quality. When cranked up high, it creates noise. This is not a problem for 'normal' users, though, unless you do recording or are just picky with your audio  :-D

Yep.  I wouldn't have used my 8KTA3 for studio recording, but *not* overdriving the output (a feature mostly provided for people with, say, eMachines, and the associated $3 unamplified speakers), it was more than adequate for dumping music to a tape for play in the car.

I intend to get myself a 24bit, high quality sound card at some point (for my PC), but these most often come without any MIDI functionality at all, so the VIA chip will continue its duty in that particular area, it's quite adequate.

A UART is a UART is a UART (and unlike RS-232, MIDI hasn't gone through the speed bumps that make an Amiga CIA different from a 16550AFN. ;-)).  If you want to use the 686B as an instrument itself, it's probably limited to FM synthesis or software rendering (no idea, too lazy to look up the datasheet)... Something like an SBLive (whatever model includes the onboard RAM) has the power to replace actual MIDI instruments (if you have the software to program the wavetable(s) and whatever nifty DSP transforms can be run on them), but may not be perfect for pro digital-out/waveform use if you're stuck with the 48KHz issue.

Here's someone's tests/reviews.

[Blomberg]

If you want to use the 686B as an instrument itself, it's probably limited to FM synthesis or software rendering (no idea, too lazy to look up the datasheet)... Something like an SBLive (whatever model includes the onboard RAM) has the power to replace actual MIDI instruments (if you have the software to program the wavetable(s) and whatever nifty DSP transforms can be run on them), but may not be perfect for pro digital-out/waveform use if you're stuck with the 48KHz issue.

I only use the controller part of the VIA MIDI, as I came to the conclusion some time ago, that all sound cards builtin MIDI sounds are crap by definition  :-D
I just use it to send events from my keyboard into the computer, for use with virtual instruments, soft samplers etc.

[Floid]

Blomberg wrote:
I only use the controller part of the VIA MIDI, as I came to the conclusion some time ago, that all sound cards builtin MIDI sounds are crap by definition  :-D
I just use it to send events from my keyboard into the computer, for use with virtual instruments, soft samplers etc.

Well, as others have pointed out to me, the chipset(s) on the SBLives are quite literally the equivalents of standalone Emu synths.  Whether Emu's products are/were  any good, or the 10k1/10k2(?) are worthwhile successors/continuances of the lineage, are probably largely subjective calls.

And, of course (and just to illustrate the technical point), for that purpose, you don't need a "sound card" at all- just the MIDI UART, as was built into the Atari ST and available on various cheap Amiga adapters only a few weeks after launch.  It's just that, these days, there's no sense in wasting a whole chip on a 'glorified serial port,' when you can put in something a few times more powerful than Paula, and maybe a wavetable ROM, an IDE controller, and who knows what else without using up all the space on the minimum die size the chip-processing machinery can handle.

[Waccoon]

And they said it was VIA's fault

The problem is with the Win32 kernel, and how it uses interrupts, as far as I know.  Win32 doesn't allow any task to completely interrupt the system (supposedly), so sound latency problems arise.  As for Linux, I have no idea, but I'm sure the PC's horrible IRQ sharing hack has something to do with it.

That's why I want to hear a Live! or Audigy card on an Amiga.  I'd be interesting to see how differently a PPC based machine handles sound latency issues.

IMO, sound has always been the PC's major fault.  That explains why I spent most of my time sampling and creating music on my A1200.  Audition 4 for the Amiga is still one of the few sound editors out there that does realtime mixing (on the PC, the few sound editors that support previews simply mix clips a few seconds long.  Pssh).

[seer]

On a slightly different note, but still a bit ontopic...

I have a SB live Value installed at the moment, but also got a  SB-Live with the gold plated pci edge connector and line in/outs (ThanX for mdma for typing that part  ;-) ) from a friend who doesn't need it anymore... Anybody care to tell which one is better ?

[Floid]

Waccoon wrote:

And they said it was VIA's fault

The problem is with the Win32 kernel, and how it uses interrupts, as far as I know.  Win32 doesn't allow any task to completely interrupt the system (supposedly), so sound latency problems arise.  As for Linux, I have no idea, but I'm sure the PC's horrible IRQ sharing hack has something to do with it.

Well, that's the problem in your *audio output.*

The other problem is that something about the Via chipset (KT133/133A + 686A/B) can't handle PCI bursts more than... X length, while Y length is the standard.  Further, it wouldn't recover properly from a failed attempt, leading to a latency on the PCI bus that made other transfers time out- not good for disk accesses, at least not with drivers that assumed the data in-flight was safe.

Audio will crackle on nearly *any* soundcard with Win2k; that's a dumb kernel bug.  However, disks could presumably corrupt on any *OS* run on the Via hardware, pre-patches-and-workarounds.

Needless to say, Via's later PCI implementations have, as far as I know, been much improved.

That's why I want to hear a Live! or Audigy card on an Amiga.  I'd be interesting to see how differently a PPC based machine handles sound latency issues.

Hear it under anything non-2k, preferrably on a non-KT133x board.  (I'm not sure which other Via chipsets were affected.)

Your audio should *never* be crackling, that's just lame.  The low-latency aspect of OS4 is more to help people who *really* need realtime response (studio/live/realtime effects work, stuff that needs to be synchronized to external triggers, etc) ... of course, it might help your Quake guy grunt a little more rapidly when you jump, too.

IMO, sound has always been the PC's major fault.  That explains why I spent most of my time sampling and creating music on my A1200.  Audition 4 for the Amiga is still one of the few sound editors out there that does realtime mixing (on the PC, the few sound editors that support previews simply mix clips a few seconds long.  Pssh).

You certainly outclass me there, but I'd be... not surprised, but amused... if the Windows software sucks that bad.  I use realtime mixing (well, MUXing) with FreeBSD's vchans daily- not to say the quality or latencies are anywhere near perfect- and DirectSound and all that has similar code built-in, too.  I assume you mean more in the sense of filtering/equalization/realtime effects, in which case I'd certainly agree... but I'd wonder how much of that is latencies showing through, vs. unnecessarily piggish effects code.

seer wrote:
On a slightly different note, but still a bit ontopic...

I have a SB live Value installed at the moment, but also got a  SB-Live with the gold plated pci edge connector and line in/outs (ThanX for mdma for typing that part  ;-) ) from a friend who doesn't need it anymore... Anybody care to tell which one is better ?

The Gold plated in/outs are better for obvious reasons.  :-D

[Hammer]

The problem is with the Win32 kernel,

I recall, Win32 is the application layer, which sits on top of NT’s Executive (includes NT’s kernel). Windows 2K/XP system drivers run on kernel level not on application level.

[Tomas]

If you want to do decent recording, the sb live is not for you anyways... SB live has nice playback quality but the recording is VERY poor, the good old sb awe64 is WAY better... I think even the ac97 has better recording quality..

But then again it might be the via chipset compitable probs that caused me this? I have tested both sb live player 5.1 and some other sb live card.. both very poor recording..

[B00tDisk]

I think it's largely irrelevent; unless you can sling a soldering iron and build your own sound-card, the AC97 on the A1 board is inaccessable - eyetech flat refuses to provide the ... what, $1?  $2?  AMR to allow it's use.