Static/distortion on recording in Yosemite

[Gale Andrews]

Guess what! The crackling/static/whatever is back in full force!!!!!!! Using Audacity Jan25 Nightly Debug version on Yosemite 10.10.2. It really messed a very important recording and there is nothing I can do about it now. Grrrrr...........

Debug versions are slower than release versions. It's good to use them to debug crashes but it may not be advisable to use them for mission critical recordings.

2.1.0 has been released now: http://audacityteam.org/download/mac.

The problem that was fixed was an uninitialised buffer. It won't help if there is some systemic problem causing crackling such as a sub-optimal buffer setting (Audacity > Preferences... then the Recording section) or if some interference is setting up crackling.

I do suggest experimenting with Audio to buffer if you have not yet done so. This can solve some crackling issues, mostly playback issues but sometimes recording issues too. Try taking it below 100 as well as above.

Do recordings made in GarageBand or with some other app have crackle, or only those made in Audacity?

I hadn't done any recordings for a while as I only do it as a backup person. Had to do one again this Sunday and the situation is exactly the same as before. Do one recording and all is fine. Save file then close Audacity to try and keep from having any issues.

It may be better to do File > Quit Audacity, not File > Close (if that's what you mean).

Restart Audacity and let sit for probably 45 minutes then start recording.

What happens if you only launch Audacity when you want to record?

First 15 minutes are fine then gradually the popping sound starts and gets worse until the recording is finished, about 30 minutes. The popping is only heard when other sounds are being recorded. During a speaker's pause, all is quiet including no popping.

The sound at the end reminded me of a machine gun. Very regular sharp pops. On the medium volume passages the pops are visible on the wave form.

I am not sure it will help us greatly, but please could you attach a sample: How to post an audio sample.

I am using a wireless mic to a receiver and the receiver's output is routed to Line-in on my 2009 MacBook Pro. The midi sample rate is set to the same as Audacity, 44,100. I am recording mono since there is only one channel coming from the mic. Now that I think about it I may have gone to Stereo recording at the end of my last episode several months ago. Hopefully that wouldn't be an issue.

The laptop has other programs minimized, but none that use audio and none are actively running doing anything. Swap file is not being used, lots of extra memory. No Internet connection available.

The problem that was fixed did not cause crackling to start a long way into a recording, as far as I know.

How long is it since you rebooted the laptop?

Can you monitor the receiver's output in headphones? Is the crackle there?


Gale

[cmac185]

cmac185 wrote:
Guess what! The crackling/static/whatever is back in full force!!!!!!! Using Audacity Jan25 Nightly Debug version on Yosemite 10.10.2. It really messed a very important recording and there is nothing I can do about it now. Grrrrr...........

Debug versions are slower than release versions. It's good to use them to debug crashes but it may not be advisable to use them for mission critical recordings.

2.1.0 has been released now: http://audacityteam.org/download/mac.

The problem that was fixed was an uninitialised buffer. It won't help if there is some systemic problem causing crackling such as a sub-optimal buffer setting (Audacity > Preferences... then the Recording section) or if some interference is setting up crackling.

I haven't played with the buffer sizes, but I'm 99.9% sure it is not interference because my son who usually does the recording also does it on a Mac, using 2.0.6 running Snow Leopard and he NEVER has had this problem and here I've had it a total of 3 times months apart. The strange part is that it always is on the second recording of the morning and never on the first and the second one starts out just fine so things are going along just right then something crops up, gets behind or something.

I do suggest experimenting with Audio to buffer if you have not yet done so. This can solve some crackling issues, mostly playback issues but sometimes recording issues too. Try taking it below 100 as well as above.

Will do, but the part of the problem is that the issue is NOT REPEATABLE. I came home after the recording and found the issue so did some more recording here at home trying to mimic the conditions that were during the morning recording and could not duplicate the problem. Same thing as what happened back in January. I spent hours trying different things like loading up my system and recording etc. Nothing would cause the slightest glitch.

Do recordings made in GarageBand or with some other app have crackle, or only those made in Audacity?

Haven't tried other apps for the critical recording. Again, if only I could find a way to duplicate the problem then I could track down the issue.

cmac185 wrote:
I hadn't done any recordings for a while as I only do it as a backup person. Had to do one again this Sunday and the situation is exactly the same as before. Do one recording and all is fine. Save file then close Audacity to try and keep from having any issues.

It may be better to do File > Quit Audacity, not File > Close (if that's what you mean).

I was doing Cmd+Q

cmac185 wrote:
Restart Audacity and let sit for probably 45 minutes then start recording.

What happens if you only launch Audacity when you want to record?

Could try that. I've even thought about rebooting the entire machine to be safe, but of course that doesn't track the problem down either.

cmac185 wrote:
First 15 minutes are fine then gradually the popping sound starts and gets worse until the recording is finished, about 30 minutes. The popping is only heard when other sounds are being recorded. During a speaker's pause, all is quiet including no popping.

The sound at the end reminded me of a machine gun. Very regular sharp pops. On the medium volume passages the pops are visible on the wave form.

Any idea what could cause the pops to ONLY sound when other sounds are being recorded. I suppose they may be happening during the quiet parts, but it seems as if there is a reaction to something that causes the pops to either happen or get louder when the sound gets louder. This boggles my mind.

I am not sure it will help us greatly, but please could you attach a sample: How to post an audio sample.

Will do.

cmac185 wrote:
I am using a wireless mic to a receiver and the receiver's output is routed to Line-in on my 2009 MacBook Pro. The midi sample rate is set to the same as Audacity, 44,100. I am recording mono since there is only one channel coming from the mic. Now that I think about it I may have gone to Stereo recording at the end of my last episode several months ago. Hopefully that wouldn't be an issue.

The laptop has other programs minimized, but none that use audio and none are actively running doing anything. Swap file is not being used, lots of extra memory. No Internet connection available.

The problem that was fixed did not cause crackling to start a long way into a recording, as far as I know.

How long is it since you rebooted the laptop?

Can you monitor the receiver's output in headphones? Is the crackle there?

At the time it had been 8 days since rebooting.

Could monitor via Audacity the Sound Playthrough setting.

Cliff

[Gale Andrews]

I think the problem is dropouts - you don't hear them between phrases because there is no surrounding audio. You might find something useful here Managing Computer Resources and Drivers - Audacity Wiki. I think it may well not be an Audacity issue.



Gale

[cmac185]

Hi Gale,

Thank you for taking time to work with me to solve this perplexing problem.

You've come to an interesting conclusion - Dropouts. Well, could be I guess. That would explain one of the mysteries anyway.

Thinking about this issue, I was realizing that in contrast to my son's MacBook Pro which has zero problems recording, mine is slightly faster, has twice the RAM and a SSD HD so should be significantly less hardware limited. The big difference is in the OS.

The thing I still can't wrap my mind around is why does it always happen on the second recording and only in that recording environment. I can record all day long at home, run anything along side Audacity, load up the CPUs so they are pegged out and there are no problems with the recording. What could possibly be different with using the wireless mic setup with the receiver going into the same line-in jack over just recording from a tape player at home? Could the recording of speech put a different type of load on the software/hardware than recording music?

I read the pages in the manual you suggested and there are things I could do to maximize the possibly of a good recording and I will try those, but I still come up with the question - why only at church and never at home. There is no sound system or other large electronic setup that could cause issues. I just pick the laptop up and carry it to church, put it on a table, hook up the mic and record. I do absolutely nothing different there from at home. If you can think of anything, no matter how off the wall, that could be different please share it as I'm totally out of ideas. It just makes no sense to me.

Blessings,
Cliff

[Leland]

The thing I still can't wrap my mind around is why does it always happen on the second recording and only in that recording environment. I can record all day long at home, run anything along side Audacity, load up the CPUs so they are pegged out and there are no problems with the recording. What could possibly be different with using the wireless mic setup with the receiver going into the same line-in jack over just recording from a tape player at home? Could the recording of speech put a different type of load on the software/hardware than recording music?

I'm not Gale and am probably asking stupid questions, but:

Is the laptop running on battery at church? At home? Does it happen to go to sleep between recordings at church? Does it go to sleep between recordings at home?

How much time is there between recordings? Could you "power cycle" the wireless mic and receiver during that period? Have you tried rebooting the laptop during that period (without cycling the mic)? Basically, trying to see if the noise is coming from the mic/receiver or laptop/Audacity.

Leland

[kozikowski]

The laptop has other programs minimized,

Such as? Is Skype in that list?

it always happen on the second recording and only in that recording environment.

Where is the radio microphone transmitter (hip pack) at the two performances?

Koz

[kozikowski]

If you drag-select a second between words on your clip and Effect > Amplify > OK, (watch the volume) you'll find that the "silent" stretches are seriously disturbed. I wonder using that test if the damage starts earlier in time than you think.

The live voice sound is clean during all this, right? Where does the receiver get its power from?

What's the model numbers of the radio-microphone?

The other half of troubleshooting that nobody thinks about is making it worse. Start a recording at the church and walk over to the computer wearing a fully operating radio microphone. Wave it around, get it close to the sound cables. Announce as you go. "I'm standing next to the laptop about three feet away." You probably don't need to run the full-on PA system and so don't need to worry about feedback.

Koz

[cmac185]

Thanks for the input everyone. I'll try to respond to everyone at once.

Leland:

The Laptop is connected to power both places. No battery use.

It does not go to sleep other than suspend when moving from home to church.

Time between recordings is about 45 minutes. The screen saver operates during that time and Audacity is open, but not yet in record mode.

The mic is powered off between recordings, but not the receiver. I have not rebooted the laptop between times. I'm pretty sure that would solve the problem in the sense that we would be back to doing a "first" recording rather than the second. Skirts around the problem, but doesn't solve it and for sure sometime it won't get rebooted and the issue will crop back up.

I'm 99.9% sure the issue isn't in the mic system as I have said before my son normally does the recording and he has for years and never once has he had this problem. There is no PA system anywhere. The mic system is only for recording.

Koz:

Skype is not in the list. There is no Internet access available so nothing can be accessing the Internet. I probably should close FireFox though it is is sleep mode.

In both cases the mic transmitter is on the speaker's belt about 20 feet away from the receiver & laptop.

Looking at the area on the clip you mentioned I see stuff there and going back to the first recording there is similar noise. I suspect it is the sound of the air conditioning fans that are always running in the background.

Live voice is clean. The receiver is powered by the same power strip that powers the laptop.

I don't have the model info on the mic system here at home. I can do the proximity test you suggest, but if that was a problem wouldn't it appear on my son's computer as well?

Cliff

[Gale Andrews]

The Laptop is connected to power both places. No battery use.

It does not go to sleep other than suspend when moving from home to church.

Time between recordings is about 45 minutes. The screen saver operates during that time and Audacity is open, but not yet in record mode.

The mic is powered off between recordings, but not the receiver. I have not rebooted the laptop between times. I'm pretty sure that would solve the problem in the sense that we would be back to doing a "first" recording rather than the second. Skirts around the problem, but doesn't solve it and for sure sometime it won't get rebooted and the issue will crop back up.

Rebooting when you reach the church would be a good test.

Another test would be not rebooting, but quit Audacity (COMMAND + Q) before leaving home and launch it when you want to record.

Another test if you have enough battery, is to use battery not mains power. Mains power is a known source of noise in laptops - perhaps it might reduce the jagged-looking noise that Koz remarked on.

This may well be to do with Mac's power management and/or App Nap - but that said, turning off App Nap for Audacity hasn't helped in any of the cases of "crackle" or "dropouts" as far as I know.

What operating system is your son's machine running?

Gale

[cmac185]

Gale,

FYI, Audacity is not running at home before I go to church so it gets started for the first recording. I've tried leaving it running and just saving and closing the session for the first recording then opening a new session for the second as well as this last week, quiting Audacity (Cmd-Q) after the first recording and restarting it, however it was left started about 45 minutes, but not in record mode, before the second recording started.

I could easily run on battery.

My son's OS is OSx Snow Leopard, I think it is OSx 6.4.? I've heard that even though it lacks a lot of the newer features, it probably is the best version overall that has been produced.

I've wondered about the effect of all the power saving "features" in Yosemite. Would be nice if there was an easy way to temporarily disable them. In the Wiki pages you mentioned there was a way to increase the priority of Audacity. That is tempting to try though as mentioned previously purposely loading up the system with all kinds of stuff running doesn't seem to bother Audacity at all when I'm at home.

Somewhere is all this there is a key that will explain the issue if only we can find it. I wouldn't mind if it was an unfixable issue if I could work around it, but just to know what the enemy is so I don't unexpectedly get a botched recording any more.

I'll be doing recording in parallel with my son for a couple of weeks by splitting the output of the mic receiver into our laptops and see if I can get a botched recording when he doesn't. That'll prove at least that it is internal to my laptop and not some bizarre external issue.