Events can be generated and consumed at quite a high rate, so event memory
management can be critical for performance and especially latency.
Applications might implement different solutions to deal with this, so I
wanted to keep GleamCore flexible in this area. In fact, the non-optional
parts of GleamCore don't do any allocation or de-allocation of events; the
MIDI converter does, but it's just meant to be a helper to deal with MIDI
data and its use by the application is completely optional. Perhaps it
should be moved out of GleamCore, as nothing in GleamCore depends on it.
Another general target is to avoid any calls to memory allocation functions
(which have potentially unbounded duration) in the synthesis thread. At the
moment we're still quite far from that target, but the freeing of events is
the most important place, I think, where this idea impacts design rather
than just implementation, so I wanted to try to get it right as early as
possible.
Virtual functions have a cost both in compile-time optimization and run-time
performance and should be avoided in time-critical code whenever
reasonable. Events could have a virtual callback to notify of their
consumption, but that would be quite expensive. The intended way to know
when a point has been reached in the event queue is the condition sync
event, which has minimal cost for the synthesis thread. An example of its
usage its provided in playmidi.cpp:
/* add a condition sync event so we know when all events have been
played */
GleamConditionSyncEvent&
endEvent(events.addType<GleamConditionSyncEvent>()());
endEvent.freeList = &freedEvents;
endEvent.time = lastTime;
[...]
/* wait until the end event is played */
endEvent.conditionSync.wait();
Hope these answers some of your questions.
Regards,
Miguel
On Sun, Apr 20, 2008 at 4:13 PM, Guillaume Pothier <[EMAIL PROTECTED]>
wrote:
> Hi Miguel, thanks for your help.
> Indeed I think the autorepeat feature should be implemented outside of
> GleamCore. Maybe I wasn't very clear in my previous mail, but what I
> wanted to do was to provide a subclassed list to the midi loader so
> that I could be notified when events are consumed. So all this extra
> code was outside of Gleam, the only change I had to do to Gleam itself
> was to declare the addNode methods of GleamList virtual.
> I'm wondering, what is the intended use of this freed events list? I
> guess it is for deallocating the memory of the events, right? I was
> thinking that it might be more generic to use a callback, rather than
> storing the events in a list. So if someone needs to have a list of
> freed events, they can do it by providing a proper callback. If
> someone wants to do something else, like this autorepeat stuff, or
> directly deleting the events, they can also do it. What do you think?
> g
>
>
> On Mon, Apr 21, 2008 at 3:20 AM, Miguel Lobo <[EMAIL PROTECTED]> wrote:
> > Sorry again, I did not try compiling with the debug log disabled. It
> should
> > work now.
> >
> > It's important to keep the intended purpose of GleamCore as simple and
> easy
> > to understand as possible (and reasonable), so I think a feature like
> your
> > propose would be better implemented outside GleamCore. For example, in
> the
> > playmidi example, you have this code:
> >
> > /* add a condition sync event so we know when all events have been
> > played */
> > GleamConditionSyncEvent&
> > endEvent(events.addType<GleamConditionSyncEvent>()());
> > endEvent.freeList = &events;
> > endEvent.time = lastTime;
> >
> > [...]
> >
> > /* wait until the end event is played */
> > endEvent.conditionSync.wait();
> >
> > At that point you could add all events again instead of exiting.
> >
> > Hope this answers your question.
> >
> > --
> > Miguel
> > Check out Gleam, an LGPL sound synthesizer library, at
> > http://gleamsynth.sf.net
> >
> >
> >
> >
> > On Sat, Apr 19, 2008 at 11:23 PM, Guillaume Pothier <[EMAIL PROTECTED]>
> > wrote:
> > > Hi Miguel, thanks for your reply!
> > > I updated my working copy and now I have other errors (string.h is not
> > > imported in debuglog.h, and bad call at sf2voice.cpp:551; for now I
> > > just commented the offending statement out)
> > >
> > > I started playing around with Gleam and I was wondering how could I
> > > implement a "repeat" feature: I would like to load a short midi file,
> > > and have it playing over and over again. I thought that the simplest
> > > mean of doing that would be to overload the freeList so that whenever
> > > an event is added to it, I push it back to the synth, with an updated
> > > timestamp. First of all, does it sound like a reasonable solution?
> > > Second, to to that I would need the addNode method of GleamList to be
> > > virtual. Could that be?
> > >
> > > Regards,
> > > g
> > >
> > >
> > >
> > >
> > > On Sun, Apr 20, 2008 at 2:51 PM, Miguel Lobo <[EMAIL PROTECTED]> wrote:
> > > > Hi,
> > > >
> > > > Gleam is still very related to fluidsynth so I hope people won't get
> > > > offended if there are questions about it here. However, I don't
> always
> > read
> > > > all posts in this list (especially when I'm very busy at work like
> in
> > the
> > > > last few weeks), so please CC me on any message about Gleam to be
> sure
> > it
> > > > doesn't get lost.
> > > >
> > > > The reason Gleam from SVN wasn't compiling was that I had a change
> half
> > > > checked-in. I've now completed the check-in, so it should build.
> This
> > > > change, which is what I've been working on recently, basically adds
> an
> > > > interface to generate useful debug information. I'm trying to use
> it to
> > > > track down severe clicking problems that seem to appear in some
> > particular
> > > > songs.
> > > >
> > > > In response to your other questions:
> > > >
> > > > - Gleam might well be more CPU-intensive than fluidsynth at this
> point;
> > I
> > > > haven't checked. The reason is I'm focusing on getting
> functionality
> > right
> > > > before looking into performance optimisations. Anyone who wants to
> look
> > > > into the latter is welcome right now, of course.
> > > >
> > > > - Gleam has been designed with the idea of being able to combine
> > multiple
> > > > synthesis models (or "subsynths" as I've called them) in a single
> > logical
> > > > synthesizer. Currently only the only implemented subsynth is based
> on
> > the
> > > > SF2 spec, but I hope other subsynths will be added in the future.
> > > >
> > > > As always, anyone who wants to do *any* type of development on Gleam
> > will
> > > > have my full support as far as answering questions and so on.
> > > >
> > > > --
> > > > Miguel
> > > > Check out Gleam, an LGPL sound synthesizer library, at
> > http://gleam.sf.net
> > > >
> > > >
> > > >
> > > > On Sat, Apr 19, 2008 at 5:28 PM, Guillaume Pothier <
> [EMAIL PROTECTED]>
> > > > wrote:
> > > > >
> > > > >
> > > > >
> > > > > Hi,
> > > > > I hope this place is more or less appropriate to ask questions
> about
> > > > Gleam.
> > > > > So here are a few questions:
> > > > >
> > > > > - Gleam from svn is not building right now, I get those errors:
> > > > > /home/gpothier/tmp/gleamsynth/GleamCore/src/sf2/sf2voice.cpp: In
> > > > > constructor 'GleamSF2Voice::Private::Private(GleamCore&,
> > > > > GleamSF2SubSynth&, GleamSynthConfigurationV1&, GleamSF2Voice&)':
> > > > > /home/gpothier/tmp/gleamsynth/GleamCore/src/sf2/sf2voice.cpp:169:
> > > > > error: 'class GleamArray<GleamSF2Generator>' has no member named
> > > > > 'setCountWithoutCopy'
> > > > > /home/gpothier/tmp/gleamsynth/GleamCore/src/sf2/sf2voice.cpp: In
> > > > > member function 'bool GleamSF2Voice::on(const GleamNoteEvent&,
> > > > > GleamSF2Zone&)':
> > > > > /home/gpothier/tmp/gleamsynth/GleamCore/src/sf2/sf2voice.cpp:235:
> > > > > error: 'class GleamArray<GleamSF2Modulator>' has no member named
> > > > > 'count'
> > > > > /home/gpothier/tmp/gleamsynth/GleamCore/src/sf2/sf2voice.cpp:236:
> > > > > error: 'class GleamArray<GleamSF2Modulator>' has no member named
> > > > > 'count'
> > > > > /home/gpothier/tmp/gleamsynth/GleamCore/src/sf2/sf2voice.cpp: In
> > > > > member function 'void GleamSF2Voice::updateModulators(bool)':
> > > > > /home/gpothier/tmp/gleamsynth/GleamCore/src/sf2/sf2voice.cpp:722:
> > > > > error: 'class GleamArray<GleamSF2Modulator>' has no member named
> > > > > 'count'
> > > > >
> > > > > Is it okay to replace all those "count" by "capacity"?
> > > > >
> > > > > - Is Gleam more CPU-intensive than fluidsynth?
> > > > > - I'd like to eventually have a fixed-point synthesizer. If I have
> > > > > time I might have a try at writing one. Where would it fit in the
> > > > > design of Gleam?
> > > > >
> > > > > Regards,
> > > > > g
> > > > >
> > > > >
> > > > > _______________________________________________
> > > > > fluid-dev mailing list
> > > > > [email protected]
> > > > > http://lists.nongnu.org/mailman/listinfo/fluid-dev
> > > > >
> > > >
> > > >
> > >
> >
> >
>
--
Miguel
Check out Gleam, an LGPL sound synthesizer library, at
http://gleamsynth.sf.net
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