so...DPC latency then. Anyone know much about this ?

Discuss music production with Ableton Live.
solitarypartygroover
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so...DPC latency then. Anyone know much about this ?

Post by solitarypartygroover » Sat Jul 03, 2010 5:20 pm

I've been having problems with my new audio interface (M-audio Fast Track Ultra). There's quite a few pops and crackles when I use Live 8, even with the biggest buffer size. Now, it could just be that the M-audio is crap. However I also suspected that my laptop wasn't working as well as it could be, so I did some Googling and came across the DPC latency checker:

"The DPC Latency Checker tool determines the maximum DPC latency that occurs on your Windows system and thus enables you to check the real-time capabilities of your computer. DPC Latency Checker works independent of any external hardware. Using this tool may be helpful in the following situations:
* You experience interruptions (drop-outs) in a flow of data processed in real-time, for example an audio stream, video stream or a sequence of measuring data, and you want to find out the reason for this problem...."
http://www.thesycon.de/deu/latency_check.shtml

Sure enough, when I run that, every few seconds I get some big red bars coming up showing lots of latency in the system. Presumably, if my processor is having to deal with other devices, then it's not gonna be able to handle audio as efficiently, leading to gaps/flaws in the sound ? Is that correct ?

The DPC tool recommends switching off device drivers until you find the one which is causing the latency. It doesn't actually tell you which drivers are causing the problems. So I've been through my device manager and have deactivated all the drivers which I knew weren't essential. But the latency still remains. I did notice that if my Wireless connection drops, then the latency shoots up until it makes the connection again, but clearly there are other drivers causing problems as the latency remains even with my Wireless driver deactivated.

So, next step is to try to identify which drivers are causing the problem. Anyone know of a program that could help with this, or any other suggestions ?

Musiclab
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Re: so...DPC latency then. Anyone know much about this ?

Post by Musiclab » Sat Jul 03, 2010 7:46 pm

DPC will also report conflicts with your video card. If you are running a desk top then look into either adjusting the Hardware Acceleration option in the settings tab of the Display Properties in your graphics card settings or actually swapping out the card for another one. The first option has worked for some users with series 8 nVidia cards where as I had to swap out my series 9 card for a series 7 to kill the DPC overload.

leedsquietman
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Re: so...DPC latency then. Anyone know much about this ?

Post by leedsquietman » Sun Jul 04, 2010 12:10 am

+1

also look at your background programs, using task manager and kill anything non essential.

Graphics card drivers frequently cause audio glitching problems, and other drivers can be problematic - I disable wifi, ethernet and the CD-DVD rom driver and my DPC latency is massively reduced and usable.
http://soundcloud.com/umbriel-rising http://www.myspace.com/leedsquietmandemos Live 7.0.18 SUITE, Cubase 5.5.2], Soundforge 9, Dell XPS M1530, 2.2 Ghz C2D, 4GB, Vista Ult SP2, legit plugins a plenty, Alesis IO14.

solitarypartygroover
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Re: so...DPC latency then. Anyone know much about this ?

Post by solitarypartygroover » Sun Jul 04, 2010 1:16 pm

Thanks for the suggestions. Yeah, I switched off all graphics hardware acceleration, and it seemed to slightly improve the reported latency. But I found that actually it was the CD/DVD drive that, along with the wireless, was causing the big red peaks in DPC. I must have missed the CD/DVD drive when I first when through it, as I only realised it was causing the peaks when I went to insert the driver CD to reinstall the Bluetooth on my laptop and they just dropped off. Other drivers either had relatively minor or no effect.

What would be considered a good value for the DPC to be at ? I've currently got a minimum of around 20us, with occasional small peaks up to several hundred. Just out of interest, I'm presuming that these figures are actually milliseconds (ms), even though it states the abbreviation for microseconds (us) ?

solitarypartygroover
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Re: so...DPC latency then. Anyone know much about this ?

Post by solitarypartygroover » Sun Jul 04, 2010 4:50 pm

Ok, the thing I don't really get is that my laptop's soundcard doesn't glitch at all even on the busiest songs (currently around 25-30 tracks), provided the buffer is above ~4000 samples. When you go much below this it understandably starts sounding awful. Yet the new m-audio soundcard I've got has crackles maybe every 15-20 seconds, regardless of whether the buffer is just 128 or 4096 samples. Any idea what could be going on ? Why would my laptop soundcard be ok at 4096 but not the m-audio ?

When the crackles occur with the m-audio, the audio track that is armed to record has a red peak.

So perhaps I'm dealing with 2 causes of problems: one that is related to the laptop performance/buffer size/DPC etc, and one that is related to the m-audio being weird and sending noise ?

Khazul
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Re: so...DPC latency then. Anyone know much about this ?

Post by Khazul » Sun Jul 04, 2010 5:13 pm

Try switching off your laptop radios (wlan and bluetooth) to see if that maks a difference.
Nothing to see here - move along!

leedsquietman
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Re: so...DPC latency then. Anyone know much about this ?

Post by leedsquietman » Sun Jul 04, 2010 5:47 pm

also try downloading and installing the asio4all driver and see if that runs better than the m-audio driver - have you got the latest m-audio drivers ? they are downloadable from their website but quite often the asio4all drivers run better at lower latencies.
http://soundcloud.com/umbriel-rising http://www.myspace.com/leedsquietmandemos Live 7.0.18 SUITE, Cubase 5.5.2], Soundforge 9, Dell XPS M1530, 2.2 Ghz C2D, 4GB, Vista Ult SP2, legit plugins a plenty, Alesis IO14.

Dennis DeSantis
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Re: so...DPC latency then. Anyone know much about this ?

Post by Dennis DeSantis » Mon Jul 05, 2010 9:32 am

Hi folks,

Speaking as an individual, rather than as an official Ableton rep, I've also had some of these issues, and have been able to completely resolve them by disabling NVIDIA's "Powermizer" functionality.

It seems that Powermizer can causes audio glitches temporarily when changing the clock speed of the graphics chip. When the clock is fixed to a single speed, I've been able to eliminate these clicks.

Note: your mileage may vary, and this has not been actively tested by Ableton so far. I'm speaking only from my personal experience.

Best,
Dennis

twisted-space
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Re: so...DPC latency then. Anyone know much about this ?

Post by twisted-space » Mon Jul 05, 2010 11:26 am

Dennis DeSantis wrote:Hi folks,

Speaking as an individual, rather than as an official Ableton rep, I've also had some of these issues, and have been able to completely resolve them by disabling NVIDIA's "Powermizer" functionality.

It seems that Powermizer can causes audio glitches temporarily when changing the clock speed of the graphics chip. When the clock is fixed to a single speed, I've been able to eliminate these clicks.

Note: your mileage may vary, and this has not been actively tested by Ableton so far. I'm speaking only from my personal experience.

Best,
Dennis

+1

Found this helpful to disable powermizer (Windows only) as my video driver wouldn't let me.

smaucher
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Re: so...DPC latency then. Anyone know much about this ?

Post by smaucher » Mon Jul 05, 2010 12:22 pm

Dennis DeSantis wrote:Hi folks,

Speaking as an individual, rather than as an official Ableton rep, I've also had some of these issues, and have been able to completely resolve them by disabling NVIDIA's "Powermizer" functionality.

It seems that Powermizer can causes audio glitches temporarily when changing the clock speed of the graphics chip. When the clock is fixed to a single speed, I've been able to eliminate these clicks.

Note: your mileage may vary, and this has not been actively tested by Ableton so far. I'm speaking only from my personal experience.

Best,
Dennis
Dennis! you're the man (again ;-))! this made my last occasional spikes disappear...
you start bleeding - I start sceaming
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solitarypartygroover
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Re: so...DPC latency then. Anyone know much about this ?

Post by solitarypartygroover » Tue Jul 06, 2010 2:33 pm

Thanks for the suggestions. The asio4all drivers seem to help slightly. And I've switched off loads of devices/drivers. Plus freezing lots of tracks.

I think ultimately I've realised my laptop simply isn't designed to handle what I'm demanding from it. So an upgrade may be in order.

I'm going to ask these questions again, because no one answered them:

What would be considered a good value for the DPC to be at ? I've currently got a minimum of around 20us, with occasional small peaks up to several hundred. Just out of interest, I'm presuming that these figures are actually milliseconds (ms), even though it states the abbreviation for microseconds (us) ?

dancerchris
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Re: so...DPC latency then. Anyone know much about this ?

Post by dancerchris » Tue Jul 06, 2010 3:08 pm

The DPC latency checker has color coding for whats good (green). I would say that keep it green with occasional yellow. You hit red and you are going to snap, crackle and pop.

ASIO4ALL is not a panacea. It is a wrapper program and was made to allow soundcards without native asio drivers to have an asio "generic" driver. As a wrapper program the total latency reported in Live when using ASIO4ALL does not include the wrapper latency. Often people think that when they see low latency settings in Live using ASIO4ALL they are mislead into thinking it is a better driver than the native one, when in reality it is just additional unreported latency that is giving them the cleaner sound.

NVidia cards are a problem with audio. They work great with graphics but tend to throw DPC spikes into the system. Powermizer is not always the culprit as it is available only on the laptop cards (it is the power saving feature for laptops) but you can be sure that it will hit you on a laptop. I have had issues with my NVidia card in a desktop system and had to dial down the hardware acceleration slider in order to tame the spikes.

If you still have a problem try using RATT to find the specific hardware device that is causing the spikes.

http://www.microsoft.com/whdc/DevTools/tools/RATT.mspx

My $0.02
Live 8.4.2 / Win 8 Pro 64 bit / Core 2 Quad 2.66 GHZ / 8 Gb ram
Presonus Firepod / Axiom 49 / PadKontrol
Various guitars, keyboards, sax and friends

solitarypartygroover
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Re: so...DPC latency then. Anyone know much about this ?

Post by solitarypartygroover » Tue Jul 06, 2010 3:58 pm

Heh, I installed RATT but it seems very complex. I have no idea what I'm looking for or how to use it. Any suggestions ?

rikhyray
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Re: so...DPC latency then. Anyone know much about this ?

Post by rikhyray » Tue Jul 06, 2010 5:32 pm

solitarypartygroover wrote:Heh, I installed RATT but it seems very complex. I have no idea what I'm looking for or how to use it. Any suggestions ?
IIRC RATT works only till XP, if you on later OS might be useless.

leedsquietman
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Re: so...DPC latency then. Anyone know much about this ?

Post by leedsquietman » Wed Jul 07, 2010 10:55 pm

asio4all works with audio interfaces which have native drivers too (not just built in cards with no asio drivers), and in actual fact, in a significant number of cases, it does run at lower latencies than the native drivers. Just because you drop a lot of money on an audio interface, doesn't mean it will always have low latency, especially on PC where driver quality is widely variable.

My Alesis IO14 runs much better under asio4all (not just latency, but can run more firewire channels without dropping out), and in several other cases Focusrite, Tascam and several other manufacturers don't seem to be able to code good windows drivers and asio4all performs better.

RME, Echo Audio and Native Instruments are the only audio card makers on PC whose native drivers seem to run consistently better than asio4all IMHO. Remember this though, you might lose some features of your audio interface, such as software routing programs like RME's Totalmix, and Motu's DSP effects etc.

This is probably not the cause of your DPC spikes though, anything red means it will drop out, you need to get almost all green with the worst case scenario being the occasional yellow (just above green, not yellow just under red). Some type of driver, or IRQ conflict is causing the problem.
http://soundcloud.com/umbriel-rising http://www.myspace.com/leedsquietmandemos Live 7.0.18 SUITE, Cubase 5.5.2], Soundforge 9, Dell XPS M1530, 2.2 Ghz C2D, 4GB, Vista Ult SP2, legit plugins a plenty, Alesis IO14.

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