[ardour-users] 48 channels on ardour

John Emmas johne53 at tiscali.co.uk
Wed Jul 18 02:32:17 PDT 2007


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
>> >>
>> >>
>> >> _______________________________________________
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>> >> ardour-users at lists.ardour.org
>> >> http://lists.ardour.org/listinfo.cgi/ardour-users-ardour.org
>> >>
>> >
>>
>>
>>
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