[Ardour-Users] MIDI workflow

Kevin Thoma kevin.thoma88 at gmail.com
Mon Oct 17 11:19:10 PDT 2011

Wow, I hadn't even thought of CPU load. I'd say that makes your approach the
method of choice for lower grade CPUs/DSPs, definitely for me.

On Mon, Oct 17, 2011 at 7:38 PM, Edward Diehl <diehl at umich.edu> wrote:

> I've also been wondering about the best workflow for midi work.  I
> want to record solo piano using Pianoteq and possibly other sounds
> using Linuxsampler or Yoshimi.  That is, I'll use the same midi track
> to drive 1 or more sound generation programs.  I find that the CPU
> requirements of doing midi seem to be quite high so I've decided that
> the best approach is to do a 2 step process:
> 1)  Sequence my midi track using just A3 and Pianoteq and no effects.
>    do all the midi takes, editing.  Use low latency since audio is
> monitored.
> 2) "Bounce" midi to audio tracks (with Pianoteq, Linuxsampler, etc)
>   and then mix/master those.  Might even bounce to Mixbus since I own
>   it already.  Use high latency to minimize DSP demands.
> Initially I tried working with a midi track + audio buses like this:
> a3 midi track -> Pianoteq -> a3 bus -> a3 master
> a3 midi track -> Linuxsampler -> a3 bus -> a3 master
> I could add fx to either the bus or the master.  The above set up
> requires routing midi and audio externally of Ardour using Jack,
> though I don't think that is a big issue.  I'll automate the setup
> using a scripts start all the programs I'm using and use aj-snapshot
> for the Jack connections.  One issue is that when recording midi you
> need to use low latency (I'm running at 8.7 ms) so you can monitor
> properly.  The low latency makes the DSP problem worse.
> Below I have some results about the Ardour3 CPU requirements.  The CPU
> usage I gauge from the Ardour DSP number.  I have found that if the
> DSP reaches 100% bad things happen, like lots of xruns.
> Here are some measurements of Ardour DSP using Ardour3 Alpha10
> Setup is:
> a3 midi track -> Pianoteq -> a3 bus -> a3 master
> DSP requirements
>                       IR EQ LS LS+EQ
> Just playing      45%  54 67 82  92
> Play + record     57%  65 75 92  99
> Playback          50%  60 72 88  99
> IR = Add IR plugin on master track
> EQ = Add LinuxDSP MKIIGraph EQ on Pianoteq bus
> LS = Add LinuxSampler bus.  Route midi also to LinuxSampler playing
>     SalamanderGrand and make new A3 bus for it.
> LS+EQ Add LinuxDSP MKIIGraph EQ on Linuxsampler bus
> DSP varies a bit for above measurements.  Seems to go up if you play
> faster.  You can see that I run up against overloading the CPU when I
> drive 2 audio buses from a midi track with a few fx.  Hence, I've
> decided that I need to do midi recording and audio mastering in the 2
> step process I mentioned above.
> My laptop is a Dell 1420 with Intel Core2Duo T7100 1.8 GHz.
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