Re: [Linuxsampler-devel] Is there any progress???

[Josh G. <jg...@us...>]

On Mon, 2003-03-17 at 09:02, Steve Harris wrote:
> 
> I've had a minor epiphany(sp?) having breifly used some subset of the
> swami/fluidsynth combo I'd say we are stupid to go it out own way, we
> should integrate with the existing stuff as far as possible.
> 
> Using the swami UI made me realise just how much work has to go into it
> and it  appears (from a cursory glance) to be basicly generic, rather than
> soundfont specific as I thought.
> 
> - Steve
> 

My thoughts as well :) Of course I'm a little biased in the whole thing,
as Swami has been a hobby of mine for almost 4 years now (if including
the Smurf SoundFont Editor). In that time I've re-written the API
probably somewhere in between 2.5 to 3 times. I am starting to feel like
the underlying architecture is quite good now and am looking forward to
implementing more functionality on top of it. Keep in mind that I am
speaking of the swami-1-0 CVS branch which has not yet been released (as
in packaged, hasn't quite come together yet). I really think Swami could
use some more developers, so if anyone is interested, please contact me
or join the Swami mailing list.

I now feel it appropriate to divulge in a more in depth description of
the architecture here, forgive me if it seems lengthy or overwhelming.
Although I am quite proud of this project, please try not to take my
enthusiasm as overly bragging :)

Swami is based on 2 support libraries libInstPatch and libswami with the
GUI currently being built on top of these (although a good portion of it
may turn into a library as well). These libraries use glib/GObject
extensively (for those who aren't familiar with GObject its an object
oriented library for C, it provides an extendable type system,
inheritable classed objects with signals and properties). This means
that the underlying libraries and the functionality they bring do not
rely on GUI related libs (X, GTK, etc). The GUI uses GTK2 and is also
very object oriented (well, its getting there). I chose this
architecture because I wanted the underlying libraries to use C which I
feel is the least common multiple when it comes to programming
languages, and therefore would increase the scope of use, but also
wanted the benefit of an object oriented system. There are also C++
bindings for GTK2 (which I'm sure includes GObject, although I have not
researched this).

libInstPatch - Instrument patch library
---------------------------------------
The library that interfaces to patch files. SoundFont files are
currently supported and DLS2/gig are just now being added. Patch files
are loaded/saved from a child/parent tree structure of objects which can
be easily manipulated using the GObject properties mechanism. The
current focus is the object system, there is a little work that needs to
be done to make the file parsers usable for those who don't want to use
the runtime objects (say if just scanning a patch file for some specific
info). This library also transparently manages sample data sources
(file, RAM, ROM, swap file, etc) and different bit widths (some work
will need to be done for bit width conversion).

libswami - Everything else not directly part of the GUI or patch files
---------------------------------------
- Maintains a master patch tree utilizing signals for change
  notification
- GObject type based plugin system (GStreamer inspired)
- XML save/restore state interface (also GStreamer inspired)
- Wavetable and MIDI objects
- event queues
- Undo/Redo state history (tree based so no loss of actions will occur
after an undo/do something else), also utilizes action dependency so
arbitrary items can be undone (provided they don't depend on later
actions).

The GUI uses a master event queue (the same events that are logged to
the state history) to track patch object changes and will update itself
on regular intervals (necessary since GTK is not multi-threaded). This
also means that changing an object property will cause any other GUI
views to also be updated.

Whats ahead (lots of things to do)
---------------------------------------
Python support - pygtk has some nice scripts to generate python
interfaces for GObject code. Using this, much of the API is generated,
only some functions need to be manually written. With python I can see a
powerful web based instrument database being created. Also a GUI
embedded shell for doing complex editing tasks or creating scripts.

Flexible object oriented GUI and session load/save state (utilizing
XML). Much of this is already underway.

Generic control interface (using GValue, a container for different data
types, int, float, string, etc). This will be used for MIDI controls,
instrument effects, any object property, and all other things that can
be thought of as a control. The GUI will utilize this for flexible
control layouts, etc. Currently in the works.

Flexible canvas widget. Move sample waveform display (loop setting) to
use canvas so effects (envelopes, LFOs etc) can be overlayed on top.
Also allow any generic control to be controlled on a canvas.

A segment based waveform modeller (also canvas based). Use lines, curves
and freeform segments to create sample waveforms with loop support. A
nice side effect is multiple samples can be created at different tones
with high precision.

Instrument patch conversion
GUI hooks for DLS2/gig files
Additional patch formats (Virtual banks, Akai, GUS, etc)
Auto sample tuning with fftw (plugin already written, no GUI yet)

Free compression standard created for patch files using FLAC (a simple
proof of concept SoundFont compressor has already been written, I'd like
to extend the format to include other patch formats like DLS2).

I feel like the architecture is ready for all these features. Just needs
to be coded :) If you are still reading this, are you interested? I keep
feeling like there really isn't that much left for all this to be
realized, but sometimes it seems like its taking so long too. If I get
some expressed interest in helping with development, I'll be quick to
update the API docs on the site, post directions for checking out the
swami-1-0 branch, todo stuff, etc. Cheers.
	Josh Green