Thread: PM Comments On Direct Mode and Integer Mode

From a thread on another site I came across this link with interesting comments on Direct Mode and Integer Mode.

CHANNEL D - Support

What does it all mean?

: popcorn :

this is going to get interesting.

This is my interpretation of what he is saying:

"Here at Pure Music we are too STUPID to implement Direct Mode, but instead of admitting this we will instead trash the competition."

Pure Music has now proven that it is trash just like Amarra. It has always been a crappy program, but this takes the cake.

Dave

I'd see things a bit more nuanced:

PureMusic is clearly misrepresenting things in their Q&A, they fail to mention that 1) the "other third party product" is clearly a beta version 2) the thread was created by the developer to actively solicit feedback on the beta mode and 3) that at least in my reading most of the comments are more about "fix those minor issues so we can enjoy the amazing sound improvement" than about major system crashes.

On the other hand, 1) this provides one of the better explanations of how direct and integer modes actually work, and 2) I haven't seen any major warnings from Damien neither on his blog nor on the above mentioned thread (maybe it was hidden somewhere in the long disclaimer you had to sign, but who reads them?) that you should absolutely refrain from having any other software running if you want to avoid kernel panics. Luckily I didn't have any so far, just occasional stuttering, but some more communication from Audirvana on those potential risks I certainly would have appreciated. It wouldn't stop me from using it, as I just love the sound, but I'll be a bit more careful what else Ill do with my computer while using it.

And finally OT, so the Doctor above gets to eat some of his popcorn: to me the key reason for NEVER using Puremusic is their Most Ugly User Interface I've seen in a long time (Although Audirvana clearly doesn't win a beauty contest either, it is still bearable.)

Originally Posted by AudioDoctor

: popcorn :

this is going to get interesting.

Yep, especially since I agree with Rob 100% on this.


Paul

Originally Posted by Paul.Raulerson

Yep, especially since I agree with Rob 100% on this.


Paul

Does that mean the case for a dedicated streamer/HD box is the most compelling? I ask because I use a dedicated Mini with nothing else running. I've had no problems running the beta AV+ and there is no doubt I'm my mind it's a step forward sonically over any of the other players in their latest version.

OK, show of hands:

- Channel D says unnamed software (wild guess, the A+ beta and Bit Perfect with direct mode, not yet released) is dangerous because it skirts the OS X "sandbox" protection. "Sandboxing" came into the Mac OS in 2008 with Leopard. All those who read Channel D's warnings prior to Leopard not to use the Mac OS or any software running on it, such as Pure Music, due to lack of "sandboxing," please raise your hands.

Right, thought so.

- Channel D warns that in just the right conditions, a kernel panic could hose your whole OS and hard drive. Since they don't have Damien's source code they don't know exactly what the chances of "just the right conditions" are, but let's say they're able to make an educated guess. However, they haven't provided any estimation of what those chances are. So I thought I'd ask:

- All those who feel the chances a kernel panic will hose your whole OS and hard drive, given modern journaling and file system checks, are on the order of "Please buckle your seat belt, it could save your life," please raise your hands.

- All those who feel the chances a kernel panic will hose your whole OS and hard drive, given modern journaling and file system checks, are on the order of "Hey, I just got bit by a nuclear spider; I'll be swingin' from skyscrapers in Manhattan tonight!", please raise your hands.

Right, thought so.

- All those who feel the chances a kernel panic will hose your whole OS and hard drive aren't minuscule, but don't have any backups, please raise your hands.

Right, thought so.

- All those who've been running OS X and/or other Unix-similar systems like Linux or the BSDs for several years and have never had a kernel panic, please raise your hands.

- All those who've experienced multiple kernel panics over the years and have ever suffered an irretrievable hosing of their OS, hard drive, and all their data, please raise your hands.

Right, thought so.

- All those testing beta software on the same machine on which you're running mission critical apps/data, please raise your hands.

- All those testing beta software on the same machine on which you're running mission critical apps/data and haven't prepared by taking backups, please raise your hands.

- All those testing beta software on the same machine on which you're running mission critical apps/data, haven't prepared by taking backups, and who like to further stress the machine while you're running beta music player apps by browsing the web and running other software in the mean time (a scenario described by Channel D in their Q&A), please raise your hands.

Right, thought so.

- I note Channel D says Lion's sound quality overwhelms any advantage from integer mode. Gordon Rankin himself has commented that he thinks Lion has better sound quality. But I have to say for myself that I did some pretty extensive listening back and forth (I have an SSD, so rebooting between Snow Leopard and Mountain Lion is maybe a 20 second delay), and while A+ on Lion had some advantages (notably transients), in the critical vocal range A+ with integer mode on Snow Leopard still sounded better. Then I tried direct/integer mode on Lion, which sounded better still. (Channel D, as far as I can tell, doesn't say Lion without direct/integer mode sounds better than Lion with direct/integer mode.)

- So after the "gloom and doom" Q&A about direct mode, Channel D closes with a smiley! I might have expected a skull and crossbones after the dire warnings about the risk of losing everything on your computer, but not a little smiley face. Seems rather incongruous.

- Guess I just like living on the wild side: I think I'll keep listening to A+ on Lion in direct mode, and on Mountain Lion when that comes out next month.

After suffering a Kernal panic thanks to Amarra 2.4.1, I thought that the info from Channel D was informative. But AR+ Direct Mode/Integer with Lion is my preferred player.

Originally Posted by SteveS1

Does that mean the case for a dedicated streamer/HD box is the most compelling? I ask because I use a dedicated Mini with nothing else running. I've had no problems running the beta AV+ and there is no doubt I'm my mind it's a step forward sonically over any of the other players in their latest version.

Hi Steve - Not really, and I agree that the A+ beta does sound different, though here it has crashed several times. And caused two kernel panics. Neither of which worry me much at all.

Yes, a standalone player is less likely to crash, but that is more because it is more difficult to monkey with the installed software than any intrinsic difference. And arguably, your Mac is just as stable as the best players. In short, not to really worry, and enjoy the music. But do be sure you have good backups. Any software player can cause mayhem.

I have good backups. Proven backups that I can use to restore every last single file, complete with artwork and even the itunes library. Compete in fact, right down to the OS.

Not everybody has this safety net. They should take the minimum risk possible if they do not. Better yet, juy go buy a disk or two and make backups. Now- before there is a problem.

Jud: I think you are trying to swat a fly with a howitzer using that logic and approach.

Any of the players we use can cause a kernel panic, as can any program that is running. The probability of a well behaved program doing so is pretty much nill though. Unix is designed to wrangle misbehaving programs, and protect the system. A kernel panic is a sign of failure in doing that, and absolutely, the system in toto is at risk when one happens.

Why do you think we invented things like journaled file systems? A power outage is basically, the ultimate kernel panic.

Point is, A+ beta is much more likely to fail, catastrophically fail, than if it did not implement direct mode. Nothing at all wrong with it implementing direct mode, and most of us think it is a benefit sonically, but you are putting your system more at risk. U

Only each individual can judge how much risk they are willing to take. I'll be honest, I am not willing to run the Beta continuously.

As much as I love Amarra, it does have a memory leak that can cause crashes, so it is not running 24X7 either. And a crash is unlikely to cause me much bother, other than restoring a few disks. It is just more risk I am willing to suffer.

If my family did not use the music so much, especially while I am not here, I think I would be willing to take more risks.

Paul

You have raised good points Paul. In my case, the MacBook Pro I use for music is dedicated and backed up. If data is corrupted, I can restore it quickly.

But I felt an obligation to let other users know that there might be issues using a beta. I'm willing to take a risk to get the best sound quality possible.

Paul: Yes, I suppose you're right. I'm certainly not in favor of kernel panics, and hope Damien accumulates sufficient information through our testing by the time of the final release that it will be quite stable and any risk of panics negligible. And though I've never lost everything to a kernel panic, electrical outage, etc. (in many years of testing beta software - it's pretty common in the Linux/BSD world to have a beta/test version of the entire OS, such as Debian Sid or FreeBSD-CURRENT), I do have backups. I suppose what "inspired" my lengthy message was the vague nature of the warning combined with what struck me as a slightly too serious and scary tone. What you said above - the risk of data loss, however slight, is increased with beta software, particularly software that has a hands-on relationship with the kernel - is more along the lines that I'd personally prefer to have seen.

Originally Posted by Jud

Paul: Yes, I suppose you're right. I'm certainly not in favor of kernel panics, and hope Damien accumulates sufficient information through our testing by the time of the final release that it will be quite stable and any risk of panics negligible. And though I've never lost everything to a kernel panic, electrical outage, etc. (in many years of testing beta software - it's pretty common in the Linux/BSD world to have a beta/test version of the entire OS, such as Debian Sid or FreeBSD-CURRENT), I do have backups. I suppose what "inspired" my lengthy message was the vague nature of the warning combined with what struck me as a slightly too serious and scary tone. What you said above - the risk of data loss, however slight, is increased with beta software, particularly software that has a hands-on relationship with the kernel - is more along the lines that I'd personally prefer to have seen.

Rob is really a brilliant person, and suffers for that when he speaks tech. If you think about that and read what he wrote, mostly he is saying he doesn't want to put it in PM because of the risk, and consequent support issues. Damien is a very affable chap, and does not get upset about mistakes or issues. He just approaches them pretty calmly. Rob declares all out war on bugs and issues, and seems to take those bugs much more personally.

I am quite sure that what he wrote was an honest attempt to explain why he is reluctant to do something he knows how to do, not a slight upon A+ or anyone else.

Paul

Originally Posted by goldsdad

Hi Jud,

I think there may be confusion. My interpretation of Channel D's use of the term "sandboxing" was a reference to the memory protection scheme of all versions of OS X, which has been around for about a dozen years. That did not exist in OS 9 and earlier. I do not think he meant the formally-named Sandbox that was introduced with Leopard in 2008.

Thanks, goldsdad. As I said in another thread, I came to this forum to learn, and you've been the source of a lot of good new (to me) information.

Actually, Rob is right on the money. I just connected new G-Tech RAID Thunderbolt drive for my music library. Kernal Panics resulted. I reinstalled the program and preferences files. Kernal Panic again. I sent the log file to Damien.

I reconnected my Promise Pegasus.

Originally Posted by Mercman

I just connected new G-Tech RAID Thunderbolt drive for my music library. Kernal Panics resulted. I reinstalled the program and preferences files. Kernal Panic again. I sent the log file to Damien.

I suggest that you look into the recent OSX updates, I have heard that there was one that Apple had to roll back due to really serious problems with Thunderbolt. That may be your problem, or a contributor...

Originally Posted by Daudio

I suggest that you look into the recent OSX updates, I have heard that there was one that Apple had to roll back due to really serious problems with Thunderbolt. That may be your problem, or a contributor...

That was update 1.2. It was fixed with 1.21. I never loaded either.

Damien sent me this info to reassure everyone about the 'safety" of using the Audirvana Plus Beta:

OS X is based on a BSD (flavor of Unix) kernel that brings virtual memory (so called "protected memory") management, along with a preemptive multitasking scheduler.
These two mechanisms ensure applications play along well, and that an application hang, or crash will not impact the rest of the system:

A hang is managed by the scheduler that gives back CPU to other apps when the hung app time is up.
For crash, each application lives in its own address space ("virtual memory") and any attempt to access beyond its allocated domain fails, terminating the application (99% of crashes).

The OS service, inter application communications, … are managed through specific ports/APIs/shared memory mechanisms offered by the kernel.

No application can directly access the kernel space. This is called the user/kernel boundary. It can be crossed on by drivers inside the kernel that offer services to applications. Outside those declared services, no way.
Audirvana Plus uses such official mechanisms, period. No "open heart surgery", evil hacking breaching security mechanisms.

But the kernel lives in a single address space, thus not isolating drivers from the other. This is mainly for performance reasons. (FYI, there have been some microkernel designs with this kind of protection at all levels, but the performance hit what too high). That's why a IOAudioFamily / OSvKernDSPLib failure crashes the kernel, thus the whole system. And note that it is not that bad, some core functions being still alive as it can display the error message on the screen.

On kernel panics impact: OS X makes use of a journaling file system. This is a technology directly derived from the high end databases: the two phases commit.

First phase: you write in the journal what you intend to do, with the roll back information. Second phase: you perform the operation, and finally you erase the journal entry.
This ensures that the hard drive will always be in a consistent state, even if the system crashes (kernel panic, power loss) at the wrong time. In this case, at the next boot, it will find journal entries about incomplete operations, and perform the roll back steps to ensure the hard drive consistency.

A note about sandboxing: this is a new feature first introduced in Lion, and that will get widely used only from Mountain Lion on. Goal is to prevent malicious activity (e.g. viruses, trojans, …).
This is a trick to fool an application by making it believe it is running in a very limited system, with access to only the approved services (see: https://developer.apple.com/devcenter/mac/app-sandbox/ ). E.g. the objective is to avoid an application approved for text editing to play with USB devices.

I assume you are the same mercman as over at AA where I got the link from. I just realized it seeing your name here.

The one and only .

Originally Posted by Mercman

The one and only .

I should have given credit where credit was due.

What bozos.

I had a few kernel panics, which I reported (and sent Damien some of the panic logs). My house did not burn down. As if I didn't have enough of a reason for a lifetime boycott of Pure Muzak.

Interesting ..... been using OSX since 10.0, and sure I have had to rebuild / re-install OSX a few times BUT never due to a 'kernel panic'. The times I have had to have been due to update crashes (brr), Microsoft office going off the rails :-) and physical hard drives dying. What's a few kernel panics amongst friends .....

With respect to Audirvana Plus and direct / integer mode .... as long as I keep away from iTunes integration I have no problems at all and I do enjoy the sq.

OSX is robust and it does take special effort to fsck it over :-) but I supposed some will always find a way.