[ardour-users] 48 channels on ardour

John Emmas johne53 at tiscali.co.uk
Fri Jul 20 10:30:07 PDT 2007 

Quick question guys....

A couple of days ago I checked some 'Jack' settings after posting that I was
getting occasional audio glitches while running Ardour.  I don't think it's
anything to do with Ardour or Jack but at least I could check some things
like processor load etc.  All I did was to open QJackCtl.  I didn't actually
change anything.

Prior to doing this my system used to start Jack automatically whenever
I launched Ardour.  Now for some reason, it's stopped doing that.  I need
to first start Jack manually, then launch Ardour.  There's a setting in
QJackCtl to 'start Jack automatically' when a client needs it.  That option
is still checked but Jack no longer starts automatically.

Can anyone think what might have changed??

John


----- Original Message ----- 
From: "John Emmas" <johne53 at tiscali.co.uk>
To: <ardour-users at lists.ardour.org>
Sent: 18 July 2007 09:32
Subject: Re: [ardour-users] 48 channels on ardour


> Thanks Thomas.  I just checked some of those things you mentioned.
>
> Firstly, QJackCtl does have a Realtime option which I can check and
> uncheck
> (so presumably that's working).  My graphics card is a (very old) Matrox
> G400 so I doubt that it's taxing the CPU too much.  According to QJackCtl
> the CPU load never exceeds 5% but here are some other values (taken from
> Ardour)
>
> 48KHz/21.3mS  Buffers: p 82% (typical)  c99%  DSP 4.4%
>
> Funnily enough, I did get a glitch when I was testing all this and I
> noticed
> that the XRun count was '1'.  Unfortunately, I didn't notice whether it
> coincided with the glitch but I'll keep an eye on this.  What is an XRun
> BTW??
>
> Thanks,
>
>
> John
> Oh, and BTW - I'm not running any plug ins at all AFAIK.
>
>
>
> ----- Original Message ----- 
> From: "Thomas Vecchione" <seablaede at gmail.com>
> To: "John Emmas" <johne53 at tiscali.co.uk>
> Cc: "Kevin Cosgrove" <kevinc at doink.com>; <ardour-users at lists.ardour.org>
> Sent: 18 July 2007 07:44
> Subject: Re: [ardour-users] 48 channels on ardour
>
>
>> My first thought would be to make sure you have realtime permissions as
>> the
>> regular user.
>>
>> Easy way to tell?  Log on as root, do the problems go away?  If they do,
>> chances are your user is not enabled with realtime permissions.  I can't
>> speak for JackLab, but if they have it set up properly, it should just be
>> a
>> matter of adding to the audio group.  If they don't have it set up
>> properly,
>> exactly how to do it can vary, in most cases it would be editing one text
>> file to make sure the audio group has the appropriate permissions, and
>> then
>> adding your user to the audio group.
>>
>> Ok there might be an easier way to tell, I lied.  Can you start Jack with
>> Realtime Permissions?  the -R switch, or in QJackCtl there is a setting
>> for
>> it.  If you can then it is probably enabled, and you may need to look
>> elsewhere.  For instance when I said my board was one of the few nForce4
>> chipsets that didn't have problems with audio when a PCI-E Video card was
>> on
>> the bus, I wasn't lying.  I am not sure of the status now, but for a long
>> time after nForce4 was released, many were advised to stay away from it
>> on
>> ANY OS for audio as it would cause dropouts whenever your video card
>> sucked
>> up the bandwidth.  I believe I read JackLab was using e17 as the default
>> WM?  IN which case the 3D card probably isn't working to hard and you
>> should
>> look elsewhere, but you should be having no problem, even on your OS
>> drive,
>> playing back 4 tracks of audio continuously, except maybe if you are
>> trying
>> to play back 24/192K audio or something;)  Even then though....
>>
>> Out of curiosity, you are not running a lot of plugins etc are you that
>> might be eating up CPU?  What does Ardour or Jack report for CPU useage
>> when
>> running them while playing back?
>>
>>                Seablade
>>
>> On 7/18/07, John Emmas <johne53 at tiscali.co.uk> wrote:
>>>
>>> ----- Original Message -----
>>> From: "Thomas Vecchione" <seablaede at gmail.com>
>>> Sent: 18 July 2007 07:06
>>> >
>>> > Remember it is NOT a linear degredation in available tracks when
>>> > adding
>>> > recording and playback to the same drive.  You lose a LARGE chunk of
>>> > performance much faster.
>>> >
>>> Actually the problems I've encountered (occasional stuttering and other
>>> glitches) don't depend on recording at all.  They happen, even if I'm
>>> just
>>> playing back and not recording anything.  My drives are all 7200rpm but
>>> admittedly, I'm playing back from the same drive as my system's running
>>> from.
>>>
>>> After I installed OpenSuse, I was advised to install Jacklab which
>>> (I thought) was to give me a real-time kernel.  However, there was
>>> no improvement in performance as far as I could tell.... :-(
>>>
>>> John
>>>
>>>
>>>
>>> ----- Original Message -----
>>> From: "Thomas Vecchione" <seablaede at gmail.com>
>>> To: "Kevin Cosgrove" <kevinc at doink.com>
>>> Cc: <ardour-users at lists.ardour.org>
>>> Sent: 18 July 2007 07:06
>>> Subject: Re: [ardour-users] 48 channels on ardour
>>>
>>>
>>> > Or you would have to ahve limited resources, which the average home
>>> studio
>>> > has.  Remember it is NOT a linear degredation in available tracks when
>>> > adding recording and playback to the same drive.  You lose a LARGE
>>> > chunk
>>> > of
>>> > performance much faster.
>>> >
>>> > Meaning, lets say, hypothetically a single 200 Gig 7200 RPM drive has
>>> the
>>> > capacity to do 32 tracks of playback(I pull this from my previous
>>> > post,
>>> > but
>>> > still consider it a vast estimation) in real life.
>>> >
>>> > If you do one track recording, and 4 tracks playback, it does NOT
>>> > equal
>>> 5
>>> > tracks of that 32 track capacity.  In fact more than likely you are
>>> > probably
>>> > bordering on using up a third of that disk performance with just that,
>>> > instead of the sixth you might expect, due to the amount the head
>>> > might
>>> > have
>>> > to move around, to read from one section of the drive, and write to
>>> > another.
>>> >
>>> > Exactly how costly it is depends on many factors, how fragmented your
>>> > drive
>>> > is, how much reading and writing, etc.  but the end result is the
>>> > same.
>>> > You
>>> > can record much more reliably if you record to a drive that is only
>>> > used
>>> > for
>>> > recording, and read from a different drive.  And when you are talking
>>> > about
>>> > something on a limited time frame, that reliability can be important,
>>> for
>>> > instance doing playback of backing tracks in a live instance, while
>>> > recording your performance, not exactly uncommon.
>>> >
>>> >                    Seablade
>>> >
>>> > On 7/18/07, Kevin Cosgrove <kevinc at doink.com> wrote:
>>> >>
>>> >>
>>> >> On 18 July 2007 at 7:39, "John Emmas" <johne53 at tiscali.co.uk> wrote:
>>> >>
>>> >> > > 2 HDs would be better, one for recording to, one for playback,
>>> >> > >
>>> >> > This doesn't make sense to me.  Surely you'd have to play the
>>> >> > audio back from the same drive that it was recorded on - or
>>> >> > would you copy the audio from the record drive to the playback
>>> >> > drive after it's recorded?
>>> >>
>>> >> That does sound a bit confusing, doesn't it.  If a person is
>>> >> recording one part of a performance (e.g. guitar) along with a
>>> >> recording of other people (e.g. piano), then they'll need to hear
>>> >> the playback while they're recording.  Moving audio around during
>>> >> a tracking session doesn't sound fun.  One wouldn't have to be a
>>> >> purist about this.  It'd probably be fine to have the guitarist
>>> >> hear they're just recorded track playing back on the same drive
>>> >> where they'll be recoding overdubs.
>>> >>
>>> >> Certainly separating audio files and system (OS) files onto
>>> >> separated disks would be good.
>>> >>
>>> >> Cheers....
>>> >>
>>> >> --
>>> >> Kevin
>>> >>
>>> >>
>>> >> _______________________________________________
>>> >> ardour-users mailing list
>>> >> ardour-users at lists.ardour.org
>>> >> http://lists.ardour.org/listinfo.cgi/ardour-users-ardour.org
>>> >>
>>> >
>>>
>>>
>>>
>>> --------------------------------------------------------------------------------
>>>
>>>
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>>> > http://lists.ardour.org/listinfo.cgi/ardour-users-ardour.org
>>> >
>>>
>>
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