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Old 05-12-2009, 08:48 PM   #1
db91977
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Default Crackles & Glitches in Playback and Recorded Audio

[Update - this issue has been resolved! 05/14/2009]

I have tried Reaper a few times in the past and have been impressed. I have an opportunity to use it this weekend to record a duo, but in my trial recordings to configure some project song files, I'm running across an audio problem which I hope to resolve before my session this Sunday.

Sometimes during playback of recorded tracks, I'll hear short crackles or 'blips' in the audio output. I have Reaper installed on an external HD which is on an e-sata card in an emachines M6809 laptop (Windows XP SP3). These crackles sometimes occur on recording, and they then show up in the recorded track.

Btw my audio interface is an M-Audio ProFire 2626, running M-Audio's ASIO driver. It has worked in other applications with no problems.

I've noticed that the audio glitches coincide with disk accesses on my system drive. Every time there's a crackle, I see the system drive light flash. I thought that this was odd, since my project files and Reaper program files are on the external HD.

Can anyone suggest settings I can look for, either in Reaper or in the OS, which might alleviate this frustrating audio problem? I don't have much confidence at the moment that I will be able to get clean recordings at my session, without fixing this.

--Doug

Last edited by db91977; 05-14-2009 at 05:37 PM. Reason: Update status...
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Old 05-12-2009, 09:04 PM   #2
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Hi db

Did you set your recording path to your external drive @

Options > Preferences > Audio > recording?
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Old 05-12-2009, 10:05 PM   #3
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Yep. I created a "Projects" folder on the root of my external drive and used that for the path.

I think I'll try defragging my system drive; don't know if that would make a difference, but it's worth a try.
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Old 05-12-2009, 10:12 PM   #4
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What video card you have. Do you notice it refreshing sluggish when it crackles? Run this http://www.thesycon.de/deu/latency_check.shtml See if theres any spikes.

~Rob.
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Old 05-12-2009, 10:18 PM   #5
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Say, can you answer a couple questions for me?

1. what's your buffer size?
2. how much ram do you have?
3. have you tried increasing your buffer size?
4. have you tried recording at a lesser sample rate & bit depth?
5. Do you have a lot of effects running, and if so...
6. have you tried to turn them off while recording?

It sounds to me like your machine is swapping a little bit trying to keep up. Or, your buffer size might just be too small for your machine - just because the drivers/reaper will let you do it, doesn't mean that's the best way to do it.

A couple things you can try, and please forgive me if I'm covering things you know, but I like to be reasonably thorough:


1. shut down all unnecessary programs.
2. turn off your network card (disable it in the device manger)
3. defrag your drive using defraggler or jkdefrag (google 'em, they tend to do a better job than the built-in)
4. install more ram (maybe not an option, but hey, maybe you're loaded, I don't know.)
5. increase your buffer size in small increments until there's no more crackle. Do this with a fresh project.
6. reduce your sample rate and bit depth (44.1k/16 minimum, though)
7. turn off all effects on other tracks and on the master bus.

I'm sure others can and will elaborate and provide additional tips, but these could at least get you started. I'm running on empty as far as sleep goes, so please forgive me if I've left out something obvious!

Last edited by themensch; 05-12-2009 at 10:32 PM.
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Old 05-12-2009, 10:28 PM   #6
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Well, I just experienced some crackle and I just rebooted my machine (shutdown completely for 20 sec) and all is fine now. Try that.
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Old 05-13-2009, 03:51 AM   #7
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db91977

pure conjecture on my part...
your fourth para is very telling. imho.
sounds like an OS activity or task is interrupting the audio process somehow. monitor win task manager while your getting those hiccups.
is this your laptop ??

http://reviews.cnet.com/laptops/emac...-30921475.html

if you notice it comes with 512 ram.
there could be many reasons but one might be XP NEEDS RAM...
do you have 512 ?? it might be low memory.
try more memory. cos lots of virtual memory useage on the system drive//swapping might be occurring due to low memory.
also more info on your external drive would help.
model no please, how much cache in it ??
small cache drives can cause probs etc etc.
also please run this on your laptop..
http://www.thesycon.de/deu/latency_check.shtml
and report back. lets see what stats your getting.

in summary i suspect either low real memory, or a clunky low cache external hard drive , but it could be other reasons too.
i dont use laptops personally, cos i test too many for friends and find consumer laptops are just not up to the task of demanding daw work.
i feel another round of in depth R n D is needed for laptops to improve.
there are specialised laptops for daw work, but they can be outside the budget of some folks.
eg look at the quad core laptops at adkproaudio.com
these are a different animal with proper TI firewire also.
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Old 05-13-2009, 08:04 AM   #8
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Guys- thanks for all the suggestions- I'm at work now, but I'll try these tweaks when I get home.

manning1 - yes, that's the laptop. emachines M6809. Ancient, I know. But I upgraded it with a 7200rpm system drive and more RAM- I'm running 1.25 GB on it now.

themensch - I'll be able to answer your system questions when I get home this evening (Pacific Time).

junioreq - I'm using the built-in card that's stock on the M6809 - ATI Mobility Radeon 9600 AGP. I haven't noticed any video sluggishness when I get the audio glitches, but they are very short; I would guestimate less than 100 ms.

Last edited by db91977; 05-13-2009 at 08:11 AM. Reason: Add info
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Old 05-13-2009, 05:49 PM   #9
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Quote:
Originally Posted by junioreq View Post
What video card you have. Do you notice it refreshing sluggish when it crackles? Run this http://www.thesycon.de/deu/latency_check.shtml See if theres any spikes.

~Rob.
Rob- I downloaded and ran the Latency Check program, and sure enough, there are spikes over 4,000 usec every time the system drive shows an access (drive light flashes). Some of the spikes are over 8,000, in fact. No wonder there are audio glitches!

I tried loading an updated VIA chipset IDE driver, but that doesn't help the problem. The IDE ATA/ATAPI controller in the Hardware/Device Manager shows as a VIA Bus Master IDE Controller - 0571. One thing, though- on the IDE channel 0, which is what the system drive is on, the 'Transfer Mode' is set to 'DMA if available', but the transfer mode used is PIO. I don't know if that would make a difference, but it apparently can't use a DMA channel for the disk. Wouldn't a disk have lower latency to the OS by using a DMA channel?

I have closed all unnecessary programs in the system tray, via regedit. And I've disabled all unnecessary devices in the Device Manager. Now, if I could disable the system drive, I'd be all set! :-)

I'm pretty sure the problem is the high latency of the system drive, or, more precisely, the driver; the drive itself is a nice 7200 rpm Hitachi Travelstar E7K100.

http://www.newegg.com/Product/Produc...82E16822145099

My audio drive is a Maxtor 1 TB drive interfaced using a Cardbus e-sata adapter. I'm not sure what the buffer on that is, but it's probably either 8MB or 16MB.

I'll try a few more things, like increasing the audio buffer size. We can probably monitor the audio inputs on the channels we're recording on, so that the latency won't bother us. If all else fails, I have a couple of desktop computers with firewire cards in them; I could throw Reaper onto one of those and try it out.

--Doug
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Old 05-14-2009, 01:10 AM   #10
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Quote:
Originally Posted by db91977 View Post
I tried loading an updated VIA chipset IDE driver, but that doesn't help the problem. The IDE ATA/ATAPI controller in the Hardware/Device Manager shows as a VIA Bus Master IDE Controller - 0571. One thing, though- on the IDE channel 0, which is what the system drive is on, the 'Transfer Mode' is set to 'DMA if available', but the transfer mode used is PIO. I don't know if that would make a difference, but it apparently can't use a DMA channel for the disk. Wouldn't a disk have lower latency to the OS by using a DMA channel?
Your system drive running in PIO mode is definitely a problem and probably the culprit. A possible reason for this is the XP "PIO fallback mode" (google it). Did you *uninstall* the old VIA driver and reboot before installing the new one?
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Old 05-14-2009, 08:14 AM   #11
db91977
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Quote:
Originally Posted by Steindork View Post
Your system drive running in PIO mode is definitely a problem and probably the culprit. A possible reason for this is the XP "PIO fallback mode" (google it). Did you *uninstall* the old VIA driver and reboot before installing the new one?
No, I just installed the newer VIA driver; I didn't uninstall the old one. Actually, the IDE was using Microsoft's driver before I installed the VIA. At first, I attempted to install all of the VIA drivers in the current set, but Windows wouldn't launch after that. So I booted up using the "Last Known Good Settings" from the bootup menu and installed only the IDE driver on my subsequent attempt. That seemed to work okay- like I mentioned, the VIA IDE driver now shows up in the IDE ATA/ATAPI controller.

I'll google around for that "PIO fallback mode" as you suggest. Maybe there's a way to enable the IDE to use DMA on this laptop. I wonder if the version of XP I'm running (SP3) has anything to do with it... nah, it couldn't be that, right? It's New and Improved! ;-)

After I defragged the system disk with jkdefrag (nice defragger, btw) and raised the buffer setting on the ProFire 2626 to 4096, the audio glitches almost went away entirely. Now it only glitches when I get latency 'spikes' of close to 16,000 usec, as shown by the 'Latency Check' software found at http://www.thesycon.de/deu/latency_check.shtml. Especially when there is an extended disk access, but that only happens rarely.

At this point, I think I'll be able to use the laptop on the recording session this Sunday, but I'd feel even better if I was able to get the IDE to use DMA and keep those latencies in the green.

Thank you all for your input so far on this problem- I'm definitely making progress in getting it resolved.

--Doug
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Old 05-14-2009, 09:06 AM   #12
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Found this site: http://winhlp.com/node/10

A lot to read about the various reasons for the PIO fallback thing, but it also contains a VB script that could help right on top of the page.

Before you do that, you could try this:
- Go to Device Manager again and set the drive to "DMA if available"
- Right-click the primary IDE channel or the whole VIA controller (not sure) and select "Scan for Hardware Changes".

Oh btw... check if that 16,000µs spike also appears (once a minute or so) when the system is running idle. That could mean that the WLAN is still active which is bad.

Last edited by Ollie; 05-14-2009 at 09:08 AM.
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Old 05-14-2009, 11:24 AM   #13
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Yep! That's the best single article I've found so far about this problem. I'll try those fixes on my emachines laptop when I get home today.

I disabled the Broadcom wireless in the laptop some time ago. No, those spikes all seem to coincide with disk accesses on the system drive.

Last edited by db91977; 05-14-2009 at 11:26 AM. Reason: add info
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Old 05-14-2009, 05:26 PM   #14
db91977
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Default Primary IDE Channel reset to UDMA-5!

Success! I was able to get the system drive (Primary IDE channel) on the M6809 laptop reset and using UDMA-5. I first rolled back the driver to the Microsoft version of the VIA driver. Then I uninstalled both IDE channels as well as the VIA Bus Master controller. After I rebooted, both IDE channels had automatically re-installed themselves and had come up in UDMA mode - Primary channel UDMA-5, and the Secondary channel (optical drive) on UDMA-2.

I'm composing this post on the laptop (NIC running, obviously), while playing a Reaper Project and running the DPC Latency Checker- 99% of the latency bars are below 500 usec, and the absolute maximum is 746 usec, after about 15 minutes of operation. I've been opening and closing Firefox windows and tabs- nary a blip has been heard in Reaper's audio output.

Thanks guys, for your input, explanations, and suggestions!

--Doug

Last edited by db91977; 05-14-2009 at 05:30 PM.
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