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Audio Delay


CelloDude

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I use a MacBook and Logic Pro 7. I open Logic and audio timing is good but over time (ie. within 10 minutes), the audio playback gets more and more delayed until it starts to break up. There must be a feedback loop somewhere but I don't know where. If I shut Logic down and re-open it, all is well again for about 10 minutes.
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I play along with MIDI. The synchronization goes way off. This is a relatively new problem (ie. it didn't happen when I first got Logic 7 a few years ago). The pitch does not change. If I record audio along with MIDI after Logic has been open for more than 10 minutes, then the playback is out of sync with any pre-recorded material as well as MIDI.
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At first, it is completely sync'd. Then, when played back after about 10 minutes that logic is open, it begins to drift. At first, it is barely noticeable, but the drift gets bigger the longer the program is open. After about 20 minutes, it can be as much as 1 sec off. By this time, the audio starts to crackle and break up. It gets so bad that I have to close out of Logic. As soon as I restart the program, it's good again. I've found that if I record audio within the first few minutes of opening the program, I can get good sound. At no time do I get a message that the MIDI/audio sync is off.
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That's annoying. I vaguely remember someone with a similar problem in the past, but can't find the thread nor clearly remember what was going on.

 

Can you share all your system data (Mac OS version, Logic version, audio interface being used, etc...)? Anything else you think we should know about your system? Did it always perform like that or is it a new problem that just started popping up?

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MacBook running OS X 10.5.8, 2.2 GHz Intel Core 2 Duo, 4 GB 667 Mhz DDR2 SDRAM. I'm running Logic version 8.0.0 (I thought it was 7!). I use Event Electronics EZbus as my audio interface (USB-based). In my audio preferences, I use core audio with the EZbus, with I/O buffer size of 64. Recording delay is 0. I have Universal Track mode checked. The Process buffer range is medium,. Under the General tab, I have the Display audio engine overload message and open plug-in window on insertion checked. Track mute/solo is Fast, Sample Accurate automation is volume, pans, sends, Recording file type is Wave. Dim level is 0. Plug-in delay compensation is All, low latency mode is unchecked.

 

It didn't always do this. I cannot remember when it started but it wasn't too long ago. That's why I think I've checked a box somewhere in the program that is causing a feedback loop somehow.

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I raised the I/O buffer from 64 to 128, then to 256 and finally 512 with no change whatsoever. Very frustrating. As soon as I open a Logic project, the delay begins, first not noticeable but over time it gets worse and worse. About 1/2 hr after starting Logic, the sound is terribly delayed and it starts to crackle and break up. After an hour, the sound is unrecognizable. This occurs even if I just open Logic and walk away and never touch the project. I've looked at all the sync settings and MIDI settings and it looks OK. I've looked at my soundcard (EZBus) to make sure it's not looping somehow and I don't see anything there either.
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Questions:

 

• Are you using any Kontakt or other CPU-intensive plugs?

 

• Do you get an error message at the point where the sync sounds particularly bad?

 

• Key question: is the MIDI lagging behind the audio? Or is the audio lagging behind the MIDI? My feeling is that the MIDI is the thing that's lagging, but please confirm.

 

How to test? Solo the audio track(s) and play the track down with the metronome. See if the click and the audio play in time for the duration of the track.

 

Side note: DEFINITELY recommend updating to 8.0.2. This may not have any bearing on your problem, but it's decidedly a more stable version of Logic 8.

 

 

 

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1) I am not using any Kontakt or other CPU-intensive plugs.

2) I do not get an error message where the sync sounds particularly bad

3) Audio is lagging MIDI.

4) I downloaded 8.0.2 and ran the updater but nothing happened. I ran the unloader a couple of different times and it said everything worked but I can't find the 8.0.2 version.

 

By the way, thanks for all the help with this. I can usually figure out what's going wrong with my problems but this one has me stumped.

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David, the EZbus does not have software to control the audio interface. I've checked it all out and on the unit itself I have set the clock to internal (it only sends out of optical output and I don't have that attached). I found another person had exactly the same problem with EZBus and Logic Pro 8. He asked an Apple forum about the problem back in Sept 2009. I've copied his string below. Unfortunately, he had no replies and the string is now archived.

 

"I recently migrated back to the Mac and am now setup with LogicPro 8 and Omnisphere. It's been a while since I've setup my small studio and I'd like to use my Event Electronics EZBus audio interface/control surface. I pulled it out of storage, got it set up and it's working fine as both an audio & MIDI interface with the one following problem:

 

The audio coming into the EZBus from the Mac via USB sounds fine initially but quickly starts to degrade into pops, clicks and eventually to nothing. The process will start again if I reset the audio interface in Logic and within a minute or so of playing the signal starts degrading again.

 

It seems like it might be a bit-rate or clock sync problem but I can't seem to find any settings that correct this for good. Any ideas out there?"

 

This guy is describing my problem, except he doesn't mention the slowing down of the audio signal coming in.

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Archived

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