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Ralf Mardorf | 1 Jul 2010 10:29

[Fwd: Re: [LAD] [64studio-users] MIDI jitter]

-------- Forwarded Message --------
From: Clemens Ladisch <clemens@...>
To: Adrian Knoth <adi@...>
Cc: linux-audio-dev@...
Subject: Re: [LAD] [64studio-users] MIDI jitter
Date: Wed, 30 Jun 2010 17:28:05 +0200

Adrian Knoth wrote:
>> latency distribution:
> ...
>   3.1 -  3.2 ms:        1 #
> ...
>   3.9 -  4.0 ms:        1 #
>   4.0 -  4.1 ms:     9903 ##################################################
> ...
>   5.0 -  5.1 ms:       95 #

The default parameters of this tool are unrealistic; the next MIDI
command is always sent immediately after the previous one has been
received, which tends to align everything to USB frames.  Please use
the -w and -r options.

Regards,
Clemens
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Ralf Mardorf | 1 Jul 2010 12:04

[Fwd: Re: [LAD] [64studio-users] MIDI jitter]

-------- Forwarded Message --------
From: Adrian Knoth <adi@...>
To: Clemens Ladisch <clemens@...>
Cc: linux-audio-dev@...
Subject: Re: [LAD] [64studio-users] MIDI jitter
Date: Thu, 1 Jul 2010 11:53:22 +0200

On Wed, Jun 30, 2010 at 05:28:05PM +0200, Clemens Ladisch wrote:

> >> latency distribution:
> > ...
> >   3.1 -  3.2 ms:        1 #
> > ...
> >   3.9 -  4.0 ms:        1 #
> >   4.0 -  4.1 ms:     9903 ##################################################
> > ...
> >   5.0 -  5.1 ms:       95 #
> 
> The default parameters of this tool are unrealistic; the next MIDI
> command is always sent immediately after the previous one has been
> received, which tends to align everything to USB frames.  Please use
> the -w and -r options.

Absolutely. I already suspected 4ms being correlated to USB frames
(granularity 1ms, right?)

With random wait, it looks like this:

> latency distribution:
...
(Continue reading)

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Ralf Mardorf | 2 Jul 2010 12:17

[Fwd: Re: [LAD] [64studio-users] MIDI jitter]

I'm not forwarding every mail from LAD, but this one might be important
too. Run it with the -w and -r option, perhaps this might be the right
way to do it.

-------- Forwarded Message --------
From: Adrian Knoth <adi@...>
To: linux-audio-dev@...
Subject: Re: [LAD] [64studio-users] MIDI jitter
Date: Fri, 2 Jul 2010 12:12:54 +0200

On Thu, Jul 01, 2010 at 07:43:38PM -0400, Paul Davis wrote:

> > [[see also latency test results for USB 1.0 devices Emagic MT-4 and
> > Edirol UM-2, below reply]]
> 
> just for comparison, here are the results for an RME Digiface:
> sudo /usr/bin/alsa-midi-latency-test -w -r -R -i 20:0 -o 20:0

You're both missing an argument after -w. I wonder (but haven't
checked the source) why the tool even starts when you don't provide the
value for the wait time.

Niels, you need to re-evaluate everything, too, your data is also aligned
to USB frames as pointed out by Clemens two days ago.

I use -w 20 -r now, alsa-midi-latency-test then prints out a message like
"interval between measurements: 20.000 .. 40.000 ms".

HTH
(Continue reading)

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gustin | 4 Jul 2010 06:53
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Re: [Fwd: Re: [LAD] [64studio-users] MIDI jitter]

OK, I finally got my midisport 2x2 working (I also have a 1x but I do not 
have the right cable or connector for it) and thus was able to compare the 
results to the midi controller in my RME.

I have put the raw results below along with the command line I used.  It 
seems that there is an order of magnitude difference between the two. 
Just like with audio interfaces in general, USB sucks (actually USB sucks 
in general, it is just good enough for the tasks it is commonly used for).

Also note that I pasted the complete results from both tests (the RME test 
produced significantly shorter output due to the tighter distribution of 
results).

Both tests were completed on the same machine, one after the other.
The system is a now modest AMD 4400+ X2 (939 pin dual core  <at>  2.2Ghz) with 
3 GiB of DDR RAM and an old and slow SATA drive (Seagate Barracuda 7200.8 
family).  The sound device is an RME 9652 PCI.  The video device is an 
ATI Radeon Xpress 200G Series integrated into the motherboard.

### First the RME results ###
$ alsa-midi-latency-test -i 16:0 -o 16:0 -w 20 -r
> alsa-midi-latency-test 0.0.3
> clock resolution: 0.000000001 s
> interval between measurements: 20.000 .. 40.000 ms

> sampling 10000 midi latency values - please wait ...
> press Ctrl+C to abort test

sample; latency_ms; latency_ms_worst
      0;       1.06;       1.06
(Continue reading)

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Ralf Mardorf | 4 Jul 2010 08:14

Re: [Fwd: Re: [LAD] [64studio-users] MIDI jitter]

On Sat, 2010-07-03 at 22:53 -0600, gustin@... wrote:

> ### First the RME results ###
> $ alsa-midi-latency-test -i 16:0 -o 16:0 -w 20 -r

> > SUCCESS
> 
>   best latency was 0.96 ms
>   worst latency was 4.04 ms, which is great.

> ### Next are the midisport results ###
> $ alsa-midi-latency-test -i 28:1 -o 28:1 -w 20 -r

> > FAIL
> 
>   best latency was 2.95 ms
>   worst latency was 34.96 ms, which is too much. Please check

Theoretically it could be, that the order of the tests had influenced
the tests. I will run my tests 3 or 4 times and in addition I will run
glxgears or a real benchmark test while running the ALSA MIDI latency
test, e.g.

"Real Benchmarks
All in one
      * Phoronix Test Suite offers Unigine, Gtkperf, and a ton of other
        tests all in one - [1]
OpenGL
      * Unigine Sanctuary & Tropics Demos - [2]
GTK
(Continue reading)

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Daniel James | 6 Jul 2010 11:57
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Re: [Fwd: Re: [LAD] [64studio-users] MIDI jitter]

Hi Gustin,

> I have put the raw results below along with the command line I used.  It 
> seems that there is an order of magnitude difference between the two.

Thanks for running these tests, the results will definitely change our
hardware designs in future.

> Just like with audio interfaces in general, USB sucks (actually USB sucks 
> in general, it is just good enough for the tasks it is commonly used for).

At least you can recharge devices from a USB socket :-)

I'd be interested to know if the new RME Babyface can do any better than
the Midisport, if the problem is fundamental to USB itself.

I notice
http://www.rme-audio.de/en_support_techinfo.php?page=content/support/en_support_techinfo_steadyclock
doesn't mention USB or MIDI at all.

Cheers!

Daniel
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Mike Holstein | 8 Jul 2010 18:47
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/me tapping mic... is this thing on??

http://www.64studio.com/node/1477

ALSO, the irc channel hasnt had a topic in about a year and a half... id be glad to take on ops in there to help out... im holstein on freenode...

im not asking for anything besides information.. i feel like the roadmap should be udated, and the IRC channel either maintained, or removed as an official support option on the website... i can only imagine how much work a project like this can be, but some updated information is long overdue... thanks in advance...
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Jimmy | 8 Jul 2010 20:11
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Re: /me tapping mic... is this thing on??

Comment follows so I don't exactly top post

2010/7/8 Mike Holstein <mikeh789-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
http://www.64studio.com/node/1477

ALSO, the irc channel hasnt had a topic in about a year and a half... id be glad to take on ops in there to help out... im holstein on freenode...

im not asking for anything besides information.. i feel like the roadmap should be udated, and the IRC channel either maintained, or removed as an official support option on the website... i can only imagine how much work a project like this can be, but some updated information is long overdue... thanks in advance...

--
MH

I'm betting the developers are either wringing their hands or jumping ship because Ubuntu with a lot of money and community behind it already, has put together "Studio Ubuntu" with a realtime kernel, stock. It's not quite as cool as 64Studio but it is growing very fast.  I actually prefer having choices but if the main distro is any example, these boys dominate everything.  They're even bumping heads with RedHat... not Fedora, but the Enterprise Edition RedHat. 
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Daniel James | 9 Jul 2010 13:54
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Re: /me tapping mic... is this thing on??

Hi Jimmy,

> I'm betting the developers are either wringing their hands or jumping
> ship because Ubuntu with a lot of money and community behind it already,
> has put together "Studio Ubuntu" with a realtime kernel

Not quite. It's true that Ubuntu Studio is pretty close to our original
design for the 64 Studio distro. We were offered the possibility of a
merger by a former Ubuntu Studio project leader, but that would have
meant them being in charge and us doing the work.

As far as I know, Ubuntu Studio has technical support but no actual cash
funding from Canonical, and I think that's been the case from the
beginning of that project.

These days, our focus is not on a general-purpose creative distro,
because Ubuntu Studio and other similar projects like AV Linux provide
that. Rather, we use our distro customisation tools to create niche
products, like musical instruments, mobile devices and audio research
equipment.

There will be more free download audio/multimedia distros available from
us though, because we need to stay very close to the community that
we've helped create.

Cheers!

Daniel
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Mike Holstein | 10 Jul 2010 02:21
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Re: /me tapping mic... is this thing on??

"These days, our focus is not on a general-purpose creative distro,
because Ubuntu Studio and other similar projects like AV Linux provide
that. Rather, we use our distro customisation tools to create niche
products, like musical instruments, mobile devices and audio research
equipment. There will be more free download audio/multimedia distros available from
us though, because we need to stay very close to the community that
we've helped create."

this is exactly the kind of thing i would like to see on the front page of the website... and what about the IRC daniel? should i ask in #freenode about closing the channel? would you like some help with the channel?

On Fri, Jul 9, 2010 at 7:54 AM, Daniel James <daniel <at> 64studio.com> wrote:
Hi Jimmy,

> I'm betting the developers are either wringing their hands or jumping
> ship because Ubuntu with a lot of money and community behind it already,
> has put together "Studio Ubuntu" with a realtime kernel

Not quite. It's true that Ubuntu Studio is pretty close to our original
design for the 64 Studio distro. We were offered the possibility of a
merger by a former Ubuntu Studio project leader, but that would have
meant them being in charge and us doing the work.

As far as I know, Ubuntu Studio has technical support but no actual cash
funding from Canonical, and I think that's been the case from the
beginning of that project.

These days, our focus is not on a general-purpose creative distro,
because Ubuntu Studio and other similar projects like AV Linux provide
that. Rather, we use our distro customisation tools to create niche
products, like musical instruments, mobile devices and audio research
equipment.

There will be more free download audio/multimedia distros available from
us though, because we need to stay very close to the community that
we've helped create.

Cheers!

Daniel
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--
MH
828.250.0037
http://www.myspace.com/mikeholstein

http://opensourcemusician.libsyn.com/
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