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Crackling on Mac mini 2.66Ghz adc

May 5, 2011 | 6:16 pm

Hi I am getting intermittent crackling on sound that I am recording from the audio line in on the 2.66ghx duo mac mini. The sample attached shows the problem. If you zoom in, you can see the discontinuities that create the crackles. To be clear–this audio is being run directly from the adc~ object through a send~ receive~ pair into a buffer, and also directly from adc~ out the dac~. The problem is audible on the dac, as well as in the audio files generated from the buffer~. Any ideas?
Thanks,
Jasper

[attachment=161421,2203]


May 5, 2011 | 7:35 pm

Usually Max’s famous crackles can be solved by tweaking the vector sizes in the DSP Status window.

Also, just looking at your patch, do you really need the send~ and receive~ objects?


May 5, 2011 | 9:34 pm

Thanks for the reply! No I don’t need the sends and receives, and I can remove them. You think they make a diff?

Some more info–indeed the vector sizes helped, and interestingly enough, the problem is audible in brief moments while the image files are being written to disk as well as the longer occurrences like the one I attached. Also, running a super processor intensive script on the command line seems to make the problem happen more often and last longer. Note that the patch uses very little cpu itself most of the time it is running. Not sure about usage when it writes the files, which is every 3 sec for the images and every 5 min for the audio.

Thanks,
Jasper


May 9, 2011 | 4:21 pm

Looks like it is still there even at 4096 vector size. It might be happening more when the system has been running for longer, or when more max and jitter processing is active.
Anyone have any suggestions? This is for a week long installation that will be archived, so any improvements would be very welcome.
Best,
Jasper


May 9, 2011 | 5:11 pm

It’s good practice to get rid of objects you don’t need :)

It could be something to do with aka.shell. You also have a [sound_affects_date] object that isn’t included in the patch. What is that?


May 9, 2011 | 7:23 pm

Hi Mike,
Thanks for taking a moment to think about it. The patch did this before that aka object was there, but good thinking… I wonder if the disk writes that it does are aggravating the issue. The [sound_affects_date] object is an abstraction that provides a date string in a particular format.


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