/srv/irclogs.ubuntu.com/2019/09/19/#ubuntustudio-devel.txt

* Eickmeyer thinks it's hilarious every time someone asks for a way to do a "minimal" install and choose which packages to install when it's right there in Ubiquty.14:25
OvenWerksEickmeyer: I suppose That should somehow be done with installer too.15:15
EickmeyerOvenWerks: We've been talking about this for a while. Unfortunately most of our time has been chasing edge-case bugs like those of Wonko's.15:16
OvenWerkswhile I am sure tcl/tk could do that, A rewrite to python would probably be the best next step forward15:17
EickmeyerIt would be.15:17
OvenWerksAnd yes I have found another opps in controls  :P15:19
EickmeyerFun. Got fixes?15:23
OvenWerksI think I can... I have been working on documenting foldback: http://scott.cbbs.org/ardours-interface/foldback-strip/15:24
OvenWerksbut I think I can set that aside as done.15:25
EickmeyerAh, yes. You showed me that. Sweet. :)15:26
OvenWerksI try to keep the manual up to date as I work while I remember what I did...15:29
OvenWerksbut I have to keep a separate branch because it is not released yet. (I now remember I should add an "as of version 6.0)15:30
OvenWerksEickmeyer: what I have found is that the recomended buffer size for zita-ajbrdge is 1/2 the size of jack master. This is because the bridge adds latency and running a smaller buffer size reduces that.15:36
EickmeyerInteresting. So, %zita-buffer-variable=%jack-buffer-variable/2 or something of that sort.15:37
OvenWerksEickmeyer: however, there are limits for many USB devices. One has to remember that the main reason for the bridge at all is to add cheap USB mics to the mix15:37
EickmeyerYeah, that's true.15:37
OvenWerksand so the buffer size needs to have a lower limit15:38
EickmeyerIs there a lowest possible limit? Because if (in the unlikely event) someone has set jack's buffer to 16 then that means zita would need to be 8.15:39
OvenWerksI found that running jack at 64/2 zita could not even open my cheap usb IF at 32/2 but was fine when I set 128/2 so zita at 64/215:39
EickmeyerOk, but USB devices almost automatically mean it needs to be */3.15:39
OvenWerksSo I need to set half at anything higher than 128, and then 64 for anything lower15:41
OvenWerks*/3 is only needed for really small 32/3 for example.15:41
OvenWerksthe limit is that USB is 1ms call rate which happens to be 1/3 for 16 samples at 48000 (assuming the exact same clock)15:42
EickmeyerWhat I'm referencing is this: https://wiki.linuxaudio.org/wiki/list_of_jack_frame_period_settings_ideal_for_usb_interface15:44
OvenWerksAs intel has messed up USB with XHCI (for USB 3.0) no one can get 32/3 on their usb device anyway and so 64/2 seems to work fine even on my cheap $0.80 usb device.15:44
EickmeyerOk, interesting.15:45
OvenWerksShutting off the XHCI driver in my bios was effective in allowing me to raise the priority of my front usb port above the back (mouse) usb port15:47
EickmeyerUnfortunately not everyone's machine can do that.15:59
EickmeyerThe thing is, we can't rely on BIOS methods of fixes or workarounds because that is completely dependent on the device manufacturer.16:00
OvenWerksyup16:03
OvenWerksand as we found yesterday, high core machines have limited low latency ability16:04
EickmeyerWhich makes sense as they have to dedicate the IRQs to multithreading.16:05
OvenWerksya, my old single core P4 with hyper thread turned off was rock solid at with no xruns with .7  ms latency (16/2)16:07
OvenWerksHowever, the reality is, that use case matters16:08
OvenWerksfor recording and other daw use, a high latency is mostly ok so long as monitoring is done outside the box, either in the audio interface or an external mixer16:09
EickmeyerAgreed.16:09
OvenWerksfor live use, latency matters but who is going to drag around a server box to do that when a pi4 does the job really well?16:10
EickmeyerWell, that's why I have a laptop with dedicated graphics.16:11
OvenWerksFor mobile, low latency use the i5 4 core cpu is about the most expensive that still works well or has any advantage16:11
Eickmeyerwonko is turning into a bit of a leech.16:13
OvenWerksno worries, he has turned up a few bugs others will also find.16:21
OvenWerksEickmeyer: for the 64 samples in minimum bug, should I file a bug report before pushing?16:22
EickmeyerIf you wouldn't mind, that would be great. Shows that we're not just uploading for the sake of uploading.16:22
EickmeyerFF tends to be an interesting time.16:22
EickmeyerAlso, bug fixes are allowed after beta freeze before final freeze, but I like to cover our butts on this kind of thing.16:23
OvenWerkshttps://bugs.launchpad.net/ubuntustudio-controls/+bug/184470616:28
ubottuLaunchpad bug 1844706 in ubuntustudio-controls "Many USB devices will not bridge correctly at latencies below 128 samples" [Undecided,New]16:28
EickmeyerCool.16:28
OvenWerksEickmeyer: fix uploaded (two lines added)16:38
* OvenWerks has found another eason to not like python... in tcl everything is a string, in python typing is required str(*) and int(*) :P16:39
EickmeyerThe more you know. :)16:40
OvenWerksI seem to have forgotten what perl does16:42
OvenWerksEickmeyer: BTW the udev-rtirq package I was interested in (next cycle-ish) does not seem to work for me. It is quite a simple package and so I will probably just pull the idea and see if I can make it work. Whatever I do, would replace rtirq. I am guessing it would become a part of -controls or at least depend on it.16:49
EickmeyerYeah, that seems like a great idea. I feel as if rtirq hasn't been touched in forever.16:50
OvenWerksMy idea is that if the autojack config file (or at least some of the info) was available to a system land daemon, then that daemon would set jack master device as the highest and zita devices after. Any audio device not being used would not have it's priority raised16:51
EickmeyerYES! That might eliminate unneccesary xruns on the master device.16:52
OvenWerkslast of all, finding any MIDI devices and raise them but below any of the others. (MIDI being as slow as it is may not need a raise)16:53
OvenWerksrtirq has been changed in the last few years... or maybe the kernel has changed, because I used to be able to do usb3 and get it picked up.16:54
EickmeyerOvenWerks: autobuild didn't trigger (last change was only 21 hours ago), so manually triggered. I want to see if it builds properly before I upload to eoan.17:32
EickmeyerI have no doubt it will, but that's another thing that can bite me if I'm not careful. :)17:32
OvenWerkssorry, I should have done that.17:52
EickmeyerNo worries.17:58

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