RTA / FFT window flickering - clock ∆ unstable

miniDSP and AV Nirvana
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redmountain

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Thread Starter
Joined
Dec 8, 2022
Posts
61
Macbookpro 9,1
Macos 10.14.6
REW 3131
96khz clock
firewire stream
I get inconsistent behaviour on the fft window...
See clock ∆ in the movie
Best
Klaus
 

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  • rtaflickering_.mov
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Last edited:
This is with Firewire
I tried with USB too
tried 48khz clock
same thing...
 
Last edited:
You could try at 48 kHz to see if it is any better, but the appearance of the plot and the change in clock delta are both typical of lost samples.
 
redmountain said:
I get inconsistent behaviour on the fft window...
Click to expand...

That's a dropout in the data stream. Remove Menu Meters, the clock, the battery, and all the other widgets from the Menu Bar. Check in the Users and Groups System Pref for login items that start when you login and remove them. Might be easier to create a new account on the device without all that stuff running than to turn it on-and-off when you want to run REW.
 
For reference, I did a quick check just now with my ADI-2 Pro on a mac mini at 384 kHz, no issues.
 
> new account
nothing in the menu bar no login items
> still clock ∆
?
Macos / coreaudio ?
 
If the output and input are both from the same interface and so using the same clock it would be odd for there to be a clock delta. Java gets its audio data via coreaudio, the OS will not resample unless the sample rate for the interface(s) in Audio Midi Setup is not the same as the rate in REW.
 
...if such dropouts happen, I would hear them for sure, not ?
I can listen to the loopback and can't hear anything...
I can re-check but am alsmost sure the clocks are the same everywhere...
 
Soundpath :
Motu analog out 1+2 out ( defined as output channel mapping 3+4 in REW )
Motu analog in 5+6 as input
timing ref analog out 2
loopback input analog 6
wrong ?
 
If there are dropouts in the source they would be audible. If data is being missed because something pushes REW into the background long enough to miss an entire sample block then nothing would be audible.
 
Hmmhh...
If I start the generator and start RTA after, the clock ∆ goes down to ca. 1.8 ppm and then struggles
If I start RTA first then the generator, the clock ∆ goes down all the way to 0.2 ppm and no flickering...
Is this only on my rig ?
 
redmountain said:
If I start the generator and start RTA after, the clock ∆ goes down to ca. 1.8 ppm and then struggles
If I start RTA first then the generator, the clock ∆ goes down all the way to 0.2 ppm and no flickering...
Is this only on my rig ?
Click to expand...
There have been other reports of odd behaviours on Mac for some interfaces if the generator is started before the input.
 
There was also a report of odd behaviour once that was tracked down to different sample rates for the input and the output in Audio Midi Setup. Wouldn't think that could occur if they are the same interface though.
 
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