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Old 08-21-2018, 12:26 AM   #32
Jack Winter
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Join Date: Aug 2007
Location: Luxembourg/Spain
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Quote:
Originally Posted by Glennbo View Post
Turns out I think I have a totally usable solution. I had written a short script to get midi going, bind the second audio card, and fire up REAPER, along with a default patch mapping that gets the second card audio to inputs 3 and 4 in REAPER. That works great and very consistent.
Great news. Since I have little experience with this, would you mind doing some short tests to see if everything aligns properly? Connecting a loopback cable and using reainsert will allow you to test what the actual real world latency is as opposed to the one calculated by buffer x period / samplerate (which is the only one reaper knows about). You can even add this to the recording prefs (or to the jack command line) to hopefully get it aligned down to the sample.

Another way to check the final result would be to insert a click source on one track and then play it back on output 1/2 and recording it onto input 1/3. I don't think this solution would introduce any extra latency between the 2 cards, but it would be nice to have that verified, and I suppose it would save you some work in the future not having to move tracks to line them up

Quote:
Looks like all the snd guys are high priority now.

PID CLS RTPRIO NI PRI %CPU STAT COMMAND
420 FF 95 - 135 0.0 S irq/32-snd_hda_
421 FF 95 - 135 0.0 S irq/17-snd_hda_
424 FF 95 - 135 0.2 S irq/16-snd_ice1
467 FF 95 - 135 0.0 S irq/17-snd_ice1
48 FF 50 - 90 0.0 S irq/9-acpi
102 FF 50 - 90 0.0 S irq/16-ehci_hcd
That looks good indeed. Did you have to add the threadirqs boot flag, or did it work without it? Something I'm not sure about concerning ubuntu's lowlatency kernel configuration.
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