New PC --- avoiding the DPC Latency nightmare?

[anm]

OTOH, I am trying to get Voyage MPD inside a virtual machine. I tried a lot last night, but it seems quite complex.

 

[Thad E Ginathom]

A few minutes (about 7.5: Suite - Judy Blue Eyes) in Virtual XP gave me just about all green and yellow, with no noticeable stutter, clicks or drop outs even if a red did pass across the window.

Coming back to Ubuntu, though, and immediately playing the same thing again made it noticeable just how bad the sound quality had been in the VM. Very course. I suppose, with a VM emulating one type of card, and the host porting the sound to something else entirely, perfection is too much to ask. Pity: I had been hoping to use CoolEdit, which remains my absolute favourite editor.

Then I booted Windows --- and VLC was stubbornly... silent. Sorry; I just couldn't face troubleshooting Windows sound, I rebooted back to Ubuntu. The WinXP test will have to be another day.

 

[anm]

good news - the latency is back 100% in green after disabling onboard wifi adapter.
Not very sure about the "real" problem with playback. But in last 5 mins of listening I didn't hear it.
Update - I do see some yellow bars and absolute max is 1070. No red as yet. Touchwood!

 

[anm]

damn! heard the noise again! switching to itunes. will do a little more back & forth

 

[Thad E Ginathom]

good news - the latency is back 100% in green after disabling onboard wifi adapter.

That is good news ... unless you are playing something that you are streaming from the net!

Apparently wifi is a big cause of this.

Here's another investigative tool, from MS this time, although I seem to remember it being not particularly easy to understand RATTV3

 

[anm]

in office I use lan wire as wifi in office is quite unreliable. At home, I can probably use appletv more than the laptop, if I need to stream over wifi.

 

[square_wave]

Isn't this DPC thingy a problem only if you try and sync visuals with the sound ? When you do an HTPC, this is what you want and is very critical.

Is this an issue if all you do is access a music file (flac, wav etc...) through USB or Firewire ? In this case there is no wifi invloved too. The USB dac is connected to the USB port using a "real wire".

 

[Thad E Ginathom]

It is an issue playing sound through any interface, PCI, USB or Firewire. Wifi is not part of the symptom, it is one of the potential causes.

My simplistic understanding is that, of the waiting list of things it has to do (interrupts), the process controller simply does not regard sound as being important, so it gets put on hold while the system does other stuff. That can literally mean a pause in your sound, or a series of pauses, which will present as stuttering.

 

[square_wave]

It is an issue playing sound through any interface, PCI, USB or Firewire. Wifi is not part of the symptom, it is one of the potential causes.

My simplistic understanding is that, of the waiting list of things it has to do (interrupts), the process controller simply does not regard sound as being important, so it gets put on hold while the system does other stuff. That can literally mean a pause in your sound, or a series of pauses, which will present as stuttering.

Okay. I see the problem. This can be an issue with PCs designed to multiple things. A music server needs only the operating system and a player. Everything else including anti-virus, internet etc..will be removed. All extra services will be removed from the system. In fact there are some sellers like the one below who actually optimize the mac mini only for music by removing unnecessary code from the OS and having only the necessary programs on the system.

Mach2 Music Server

 

[anm]

What should people sitting in office do? I spent about 10 hours in office and laptop is one good convenient source. Expectation is that it should work decently well.
Dedicated music servers are a little difficult to set up in an office env. Plus dac, storage, headphone amp and headphones.

 

[asliarun]

Okay. I see the problem. This can be an issue with PCs designed to multiple things. A music server needs only the operating system and a player. Everything else including anti-virus, internet etc..will be removed. All extra services will be removed from the system. In fact there are some sellers like the one below who actually optimize the mac mini only for music by removing unnecessary code from the OS and having only the necessary programs on the system.

Mach2 Music Server

This is an interesting concept, but the way I see it, a PC is a general purpose machine that is meant to perform multiple roles. Devices and gadgets, on the other hand, excel in being able to do one job correctly, but only that job. Please correct me if I am wrong, but it looks like you want to do three jobs with your computer - store music, play back music, and rip/decode music.

Considering the limited scope of your computer, are you better off with one or two dedicated devices instead?

 

[anm]

well the DPC latency is very well behaved now - but I just heard the deafening clicks twice in last 5 mins. Much less frequency but still there.

 

[Thad E Ginathom]

Okay. I see the problem. This can be an issue with PCs designed to multiple things. A music server needs only the operating system and a player. Everything else including anti-virus, internet etc..will be removed. All extra services will be removed from the system. In fact there are some sellers like the one below who actually optimize the mac mini only for music by removing unnecessary code from the OS and having only the necessary programs on the system.

Mach2 Music Server

All PCs have to do multiple things, even when they appear to be doing nothing.

It's true that, even on a general purpose office machine, one can do stuff like go through the Windows services and turn off the useless ones (followed by a wasted day trying to find out which ones looked useless, but without which your machine will not work ) but look, we're talking playing music --- not working out the ultimate prime number, or the number of atoms in the universe. This is a problem I never experienced, or even knew about, until the past few years. how come all those old machines could do it?

 

[Thad E Ginathom]

Postscript...

I took the old machine out of storage to prepare it as a contribution to a needy student. The old partitions had been long since wiped, and I installed completely clean WinXP and Ubuntu 10.04 on it.

Just to remind myself of old times, I ran the dpclat program, and guess what...

Hey, it's perfect!

Of course, the complete reinstallation of a clean copy of Windows can cure a lot of things. Otherwise, I have a theory (no, a guess!) that the culprit might have been the Realtek Network chip. This 8111/8168 chip, despite being ubiquitous, seems to give a heap of problems to people, especially if they run dual-boot systems (I even have some trouble with it on my new card).

I did have problems with the card in WinXP (Ubuntu already installed) giving very patchy connection in Win. Could not do the heap of Win-updates that installing XP-SP1 cd ---> SP3 from usb ---> Win Updates required until I managed to download the latest Windows driver for the net card.

The machine has been unused for nearly a year, and returning to its 2.8mhz, Core Duo chip, I have to say I'm quite impressed. It's quite nippy --- without my old Win installation it. I hope it will see a young computer-science student through to the end of his course, at least. He'll be more interested in C compilers than Sound Cards...

 

[vaibhavyagnik]

i am getting red spikes but dont seem to notice any clicks. I am using a Gigabyte G31 ES2L with e7400 (2.8 Ghz), 2 GB RAM, Belkin PCI WIFI G card and windows 7 ultimate 64 bit. connected to my philips home theatre via onboard co-axial SPDIF out.

 

[Thad E Ginathom]

I was getting worse than clicks: I was getting total dropouts, echos, all sort of weird and horrible stuff. It wasn't spikes, either, it was blocks of red.

Of course, looking back on it all now, it was just plain stupid not to re-install Windows, but I seem to remember that my card didn't work much better in Linux.

Anyway, this PC is going for a new life, I have a new PC --- and lots more new problems to worry/play with