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Old 08-20-2018, 10:13 AM   #23
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Originally Posted by Jack Winter View Post
Let's leave the USB stuff for another time. But in brief, yes you should change the priority of the USB hub that you connected your sound card to. I can understand that 4 channels of audio is not really enough as a drummer, you can make nice recordings with it, but it's very nice to have more channels for spot & room mics.

The main drawback with USB is that it gives quite a lot of extra latency on Linux, and annoyingly the "hidden" extra latency changes when you change buffersize (not a fixed value). This might not be a problem depending on how you record. I don't monitor through the DAW so I just set a high buffersize, make sure that I configure reaper to properly compensate for the extra (hidden) latency and then just forget about it.

Seeing that your existing cards are PCI they likely are lower roundtrip latency and have a fixed overhead, so much nicer to use in this context.
USB might be an issue for me then, because I monitor through the DAW 100% of the time, even if I'm just jamming around on a guitar or bass. I monitor through a lot of FX on occasion as well, and never had any issues with laggy performance or artifacts in the audio. Maybe I'll just keep using my dinosaur cards that I bought when Windows 98 was king.

There is a button that says clone or download, just download the zip, unzip it somewhere and then run "make install". But let's leave that for another day, as I just saw that I didn't provide a way to run make uninstall, and there is an added hurdle to overcome on ubuntu as they have removed the sudo command. I think you can install sudo, but I'm not sure about this.
OK, I downloaded the file. As far as sudo goes, I use it more than I probably should, doing things like "sudo thunar" so I have the control freak version of the file browser, ready for me to click a config file deep in the heart of the system, and change it!

I also have the OS set to not hide anything from me, so it is a cluttered bunch of stuff in the file browser, but I can see everything that is going on.

Well let's see if we can't make that work better in Linux than in Windows But I still need to see the output of "cat /proc/asound/cards" to be able to help you.
I'm down with that! BTW, if the IRQs end up like they were in Windows, both of the 2496 cards are sharing IRQs with other stuff. One is sharing with USB, and the other with the video card, but again that was in Windows, and I presume were soft IRQs.

Here's the output.

0 [MID ]: HDA-Intel - HDA Intel MID
HDA Intel MID at 0xf9ff8000 irq 32
1 [M2496 ]: ICE1712 - M Audio Audiophile 24/96
M Audio Audiophile 24/96 at 0xec00, irq 16
2 [NVidia ]: HDA-Intel - HDA NVidia
HDA NVidia at 0xfbcfc000 irq 17
3 [M2496_1 ]: ICE1712 - M Audio Audiophile 24/96
M Audio Audiophile 24/96 at 0xe400, irq 17

You might be wise in this decision. I left Ubuntu a long time ago because it stopped providing a realtime kernel, and because I got fed up with problems, especially when doing a distro upgrade, which seemed to always end up in a complete reinstall.. I hope that this has improved since then and that your experience will be smoother.

The lowlatency kernel is already very good and there are many that claim that there is no need for a realtime kernel. Personally I would dispute this, but I might also be wrong, or it's a question of what hardware you have and how hard you push the system. The realtime kernel is basically the same (a kernel capable of preempting running threads to run other threads) but it removes some existing bottle necks in the kernel to lower thread scheduling delays. That is to say it will probably be just a bit less likely to cause xruns (dropouts) in your audio.

But as you say, no hurry and cross that hurdle when you have too

Heh, then the maudio driver did double buffering too by default. There most likely is some small additional latency that reaper doesn't know about, for hardware buffers and conversion time of DAC. This can be tested and compensated for in reaper. Most likely it's so little that you can safely ignore it, but if you want to you can use reainsert and a cable connected from an output to an input to check how much it is. You could also play back a click track and see how well the recorded track aligns to the click. On my rme hdsp it's a constant 95 samples, so about 2.1ms roundtrip. Not really worth worrying about...
As the system is running right now, I have open a stock ticker that is constantly hitting the net and parsing data, an NNTP newsgroups reader, Thunderbird mail, Firefox web browser and a bunch of other things running, and all the while looping over and over in the background, my test song in REAPER, playing without the slightest hiccup.


It will take effect on the next boot. I assume it's similarly configured on ubuntu as on archlinux, and if so the default configuration isn't optimal, as it changes the priority of a lot of things that aren't really relevant in your case, mainly all the USB interrupts too.

I'd edit /etc/rtirq.conf and change it to the following (comment out the rest):

Then after rebooting run "rtirq status" to see if it had the desired effect.

Additionally for this to work, you might have to add the "threadirqs" irq boot flag to your boot manager, I don't know if this is needed or not on ubuntu.

Note that I've hardly ever used rtirq myself, so I'm not 100% sure about all the details. But hopefully this gets it working on your system and doesn't cause any problems!
I scanned my entire system volume and found no existing rtirq.conf file. Should there be one, or is this one I need to create myself? I have rebooted and like I mentioned, I'm playing a fairly busy project in REAPER with a lot of Windows plugins and instruments while doing all my normal daily stuff like modifying my stock ticker app because now that Windows file browsing works properly, it broke my ticker, and I had to change an internal path to how Wine sees it now, which is how it should have seen it originally but comctrl altered it.

Getting both cards to work in REAPER would be the most beneficial thing for me at this point, as it seems latency is every bit as good as it ever was in Windows. Being able to record four simultaneously tracks of my acoustic drums would be another major breakthrough event for me.
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Last edited by Glennbo; 08-20-2018 at 10:24 AM.
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