Re: [fluid-dev] Major degradation in sound quality & cpu usage going from Ubuntu 11.04 to 11.10

[David Henningsson]

On 11/26/2011 12:57 AM, Aere Greenway wrote:
> David:
>
> All I can say, is I don't understand what has happened.
>
> There was a system update that installed a new kernal, which may have
> introduced a significant amount of overhead.
>
> I carefully re-installed xubuntu 11.10 on my 933 megahertz machine,
> along with the MIDI/audio software.
>
> At the last stage (after reproducing the problem), I included your PPA,
> and installed the updates.
>
> The piece only plays about 15 seconds, then stops, complaining that
> there is insufficient processor power to play it. It seemed that what
> did play, did not have voices missing, so perhaps the fix is there. I
> also verified I had set the polyphony in Qsynth to 48.
>
> That same piece plays in its entirety on the same machine using ubuntu
> 11.04, but it gets a total of 5 under-runs during the course of playing
> the entire piece. That isn't good, but it's a whole lot better than on
> xubuntu 11.10, with the fluidsynth fix in-place. This combination used
> to play flawlessly.
>
> Perhaps Canonical has decided to abandon support of people having older,
> slower machines.

This is somewhat off-topic, but yes, to some degree we (as in 
Canonical/Ubuntu) do that when we feel it's necessary and good for the 
many: Take for example when we decided to compile packages with MMX 
instructions enabled (that's like Pentium 166 MHz or something) - some 
people might have been upset if they had that old computers, but for all 
the others, Ubuntu started to run faster.

Also latest versions of upstream components sometimes require faster 
computers to be able to accommodate new features.

But please do not make assumptions about the general, given your machine 
only. If a new kernel (or something else) brings in overhead for 
yourself, it probably does that to a very minority of people - if it is 
a large overhead and it affects everyone, I doubt it would go unnoticed. 
The majority of changes that bring in regressions actually improve the 
situation for someone else; which is not to say this is OK, just saying 
that people in general do not bring in regressions just for the fun of it.

In particular the desktop environment (Unity, XFCE, etc) that you 
mentioned above, are highly dependent on graphics hardware and drivers.

> > It is possible that I forgot to set the polyphony parameter in qsynth
> > down to 64. That would have produced the observed symptoms.
> >
> > Also, there could have been a problem with enabling your PPA during
> > the initial installation of the components.
> >
> > I am re-installing, more carefully this time. I will enable the PPA
> > only at the end, after I have reproduced the problem. And I will be
> > very, very careful NOT to install the "-dev" version, which rips out
> > JACK.

As for the -dev package. For some reason I haven't investigated fully, 
it seems to want to exchange JACK2 for JACK1. I think it can be resolved 
by installing the right libjack-*-dev package manually first.

// David