Drops in recording

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Bull
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Location: Blacksburg, Virginia

Drops in recording

Post by Bull »

Good morning,

I recently recorded a multi-hour program, and find on playback that there are several places where a second or two of the input stream has been dropped. That is, the recording is continuous but lacks the few seconds of content.

The problem is I don't know where the problem originates. I'm recording from iTunes via JackOSX, but I don't see how either of those can be a problem. I'm using AP version 1.5.5 (1202), but I've recorded a lot with that version using iTunes and Jack, and never had this problem.

The computer is MacBook Air with Lion. I'm new to MacBooks and Lion. While recording I leave it unattended and connected to the power source with the lid open and Computer Sleep preference set to Never. Is it possible the system is doing some housekeeping that causes the drops?

Any ideas?

Thanks,
Wayne Durham
Blacksburg, Virginia

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Martin Hairer
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Drops in recording

Post by Martin Hairer »

Is it possible the system is doing some housekeeping that causes the drops?
Is the system performing Time Machine backups? Time Machine tends to be very unkind to other programs that try to access the disk while it's doing its stuff… Regards,

Martin

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Bull
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Location: Blacksburg, Virginia

Post by Bull »

Yes, Time Machine was doing hourly backups. I didn't time it but the recording was good for a while, then a series of drops. Maybe ... every hour or so? I'll try it again with Time Machine off. Thanks for the info.

Bull
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Save file while recording?

Post by Bull »

With respect to the dropped audio in the recording: I had selected the option to save the file to disk while recording. Assuming it was that process that Time Machine interfered with, would I have been better off not selecting that option?

supercazzola
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Post by supercazzola »

this is exactly the type of behavior I am experiencing, except that Time Machine is turned off in my instance.

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Martin Hairer
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Drops in recording

Post by Martin Hairer »

Assuming it was that process that Time Machine interfered with, would I have been better off not selecting that option?
Possibly. Even without that option checked, recording is performed to the disk, but only in a temporary file and these should be ignored by Time Machine. Definitely worth testing on your computer though, as these kind of things might depend on particularities of your specific setup. Regards,

Martin

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Bull
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Another data point

Post by Bull »

I did another long recording with the MacBook in the same state as before except Time Machine was off, and had no problems. So, either Time Machine was the culprit or something else was at work.

ThemsAllTook
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Post by ThemsAllTook »

I've been having this issue too. Time Machine definitely exacerbates it a lot; I just did some testing a moment ago while backupd was using 100% CPU, and I couldn't record 20 seconds of audio without having a lot of it dropped. I could even see the timer in the recording sheet jumping backward and forward seemingly at random.

I've done a couple of hour-long recording sessions with Time Machine turned off, and I still lose parts of them. In the one I'm working with right now, it looks like I have two sections of about 15 seconds each missing. They're spaced surprisingly evenly, which may be a clue: One is at 25:30, and one is at 51:00. I have an SSD, so I wouldn't have expected disk I/O speed to be a problem. Other specs: Early 2010 MacBook Pro, 2.4 GHz Core i5, 8 GB RAM, Mac OS X 10.6.8.

I tried recording with Audacity, and it was able to flawlessly capture everything in a 30 second recording while backupd was using just as much CPU as when I was running the test with Amadeus. So, not a thorough test, but at a glance it seems like it should be possible to record contiguously even while Time Machine is running. I'd be happy to help you troubleshoot in any way I can, since I have a pretty consistent way to reproduce the problem. Amadeus is a fantastic program, and I'd really like to be able to use it for every aspect of my audio work...but for the moment, I just can't trust it not to lose things. Have to deal with the awkwardness of Audacity for recording.

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Martin Hairer
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Drops in recording

Post by Martin Hairer »

Hi, I've just updated the version at

http://www.hairersoft.com/Downloads/AmadeusPro.zip

Could you please let me know if this fixes the issue? Thanks,

Martin

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ThemsAllTook
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Post by ThemsAllTook »

Hmm, seems it's not as consistent as I thought... I've been trying to reproduce it for the last few days, and haven't had any luck. The new version's timer still jumps around a whole lot if I watch it while recording, but even if it goes back in time a few seconds, it seems to correct itself after a bit without losing audio. I can't get drops in recording in either the old or new version anymore. I'll keep trying, though, and let you know if I'm able to do it again!

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Martin Hairer
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Drops in recording

Post by Martin Hairer »

Try it with Time Machine performing a backup. I would hope that the updated version "survives" this… The time display occasionally jumping is harmless, it just means that the sampling rate reported by the recording device is slightly off with respect to the actual clock of the computer. It only affects the display, not the actual recording. Regards,

Martin

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