Ultralite AVB

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Drumfix
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Re: Ultralite AVB

Postby Drumfix » Sat Aug 25, 2018 6:20 pm

Got my 16A today, so could test myself. While initially i had the same problems as you (random glitches, channel movement etc), they immediately vanished after i removed the prebuffering (= sending in advance) of the iso out packets.

Note: The alsa usb driver does such prebuffering of iso out packaets for all devices that do not use an implicit feedback endpoint for synchronization, like e.g. the ultralite avb.

vth
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Re: Ultralite AVB

Postby vth » Sat Aug 25, 2018 7:33 pm

Woah, sounds promising! What are the changes exactly?

rofer
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Re: Ultralite AVB

Postby rofer » Sat Aug 25, 2018 9:33 pm

I tried removing the prebuffering from your script by setting PREBUFFER_PACKETS to 0 and it might have reduced the number of errors, but I'm certainly still getting them.

supereb
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Re: Ultralite AVB

Postby supereb » Sat Aug 25, 2018 10:35 pm

It's great to hear that you have identified the root of the problem!

Drumfix
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Re: Ultralite AVB

Postby Drumfix » Sun Aug 26, 2018 5:28 am

Unfortunately i was wrong. It worked, because i had hooked it up to a windows box, where it apparently initialized correctly and then reconnected it to the linux box without rebooting the device... The search continues...

Musinux
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Re: Ultralite AVB

Postby Musinux » Sun Aug 26, 2018 7:16 am

Just found out that I can switch the web interface into a mode where I can adjust the host buffer size and host safety offset.

Via JSON, there are parameters like:

Code: Select all

"host/os":"mac",
"host/win/buffer_sizes_1x":"16:32:64:128:256:512:1024",
"host/win/safety_offsets_1x":"16:24:32:48:64:128:256",
"host/win/current_buffer_size_   1x":128,
"host/win/current_safety_offset_1x":128,
"host/win/interrupt_capable":1,
"host/win/enable_interrupts":1,


Setting "host/os" from mac to win via

Code: Select all

curl  --data 'json={"value":"win"}' <Ultralite IP>/datastore/host/os
instantly changes the device tab in the web interface.

Update:
Changing this didn't let me connect jack at all. Then dmesg had:

Code: Select all

cannot submit urb 0, error -28: not enough bandwidth
. Using USB 3.0 let me connect again.

Drumfix
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Posts: 234
Joined: Mon Jan 26, 2009 5:15 pm

Re: Ultralite AVB

Postby Drumfix » Sun Aug 26, 2018 10:50 am

More testing done. Like someone has written earlier, the device is extremly sensitive to gaps in the iso stream. My guess is it does not check the pointers of its internal ringbuffers for overflow/underflow. I run my test program for about an hour without any problems, with the irq of the host controller and test program pinned to the same processor core, which has been isolated from the rest of the system.

supereb
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Re: Ultralite AVB

Postby supereb » Thu Aug 30, 2018 1:19 pm

Drumfix wrote:More testing done. Like someone has written earlier, the device is extremly sensitive to gaps in the iso stream...


Any ideas on how this issue might surmounted?

Drumfix
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Posts: 234
Joined: Mon Jan 26, 2009 5:15 pm

Re: Ultralite AVB

Postby Drumfix » Mon Sep 03, 2018 7:00 pm

Update:

Code: Select all

curl  --data 'json={"value":"win"}' <Ultralite IP>/datastore/host/os
curl  --data 'json={"value":"USB2"}' <Ultralite IP>/datastore/host/type


will set the device into the windows driver mode where you have 64 channels at 44.1/48kHz, 32 channels at 88.2/96kHz and 24 channels at > 96kHz.
In this mode, the device is using interfaces 4 and 5 instead of 1 and 2 for streaming.

Using this mode i can run the device without the channels moving around with a modified version of my test program but i still get glitches after some time, so need to investigate more.

Musinux
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Re: Ultralite AVB

Postby Musinux » Mon Sep 03, 2018 8:20 pm

Looking at this thread http://www.motunation.com/forum/viewtopic.php?f=14&t=65037 , there might even be other layers of problems or misconfigurations, like powersaving in particular, even on windows.

Have you guys with the new firmware tried setting (usb host controllers) tunables of powertop to "bad" (i.e. full freaking power consumption) ?

supereb
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Re: Ultralite AVB

Postby supereb » Tue Sep 04, 2018 1:08 pm

Musinux wrote:Looking at this thread http://www.motunation.com/forum/viewtopic.php?f=14&t=65037 , there might even be other layers of problems or misconfigurations, like powersaving in particular, even on windows.

Have you guys with the new firmware tried setting (usb host controllers) tunables of powertop to "bad" (i.e. full freaking power consumption) ?


I have seen this before in a few Windows DAW optimization guides, not just MOTU, although based on our experiences it's likely much more critical when using a MOTU interface! I've always changed the USB settings in Windows, but never bothered to before in Linux because my Focusrite 6i6 "just worked" without changing any settings.

Musinux
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Re: Ultralite AVB

Postby Musinux » Thu Sep 06, 2018 10:28 am

https://www.gearslutz.com/board/music-computers/943494-motu-1248-8m-16a-thunderbolt-interface-87.html

Originally Posted by Rafter Man
There's a new update available. 1.2.7, but it appears the only changes are for Windows users adding the "Host Safety Offset" setting, aka USB Streaming Mode. Why only for Windows and not Mac as well?

--> The safety offset setting is not needed on OS X because Core Audio provides very stable timing. Our Mac driver uses a (very low) fixed safety offset.

Drumfix wrote:Using this mode i can run the device without the channels moving around with a modified version of my test program but i still get glitches after some time, so need to investigate more.


In the pro audio driver readme, they say that 48 is a good starting point. I think my ultralite defaulted to 64. Have you tried increasing the safety offset?

vth
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Re: Ultralite AVB

Postby vth » Thu Sep 06, 2018 10:35 am

Musinux wrote:In the pro audio driver readme, they say that 48 is a good starting point. I think my ultralite defaulted to 64. Have you tried increasing the safety offset?

I've tried setting the host safety offset to both extremes and to various values in between them, with no perceivable difference. This with the latest firmware.

rofer
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Re: Ultralite AVB

Postby rofer » Thu Sep 06, 2018 12:07 pm

Has anyone else tried asking MOTU about this?

It looked like they were responsive over on gearslutz so I figured it might be worth pointing them to this thread. I'll report back if they're able to help.

rofer
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Joined: Fri Apr 27, 2018 1:26 am

Re: Ultralite AVB

Postby rofer » Thu Sep 06, 2018 10:13 pm

I got a suggestion to try "v1.2.4+201 (Release Date 2015-12-01)" and a reminder that MOTU doesn't officially support Linux which is about what I expected.


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