Well, I don’t think there’s an open source or even a free solution to this… and if there were one, I doubt it would give you a lot of quality and choice. If you want string instruments you can try a google for that specifically (the examples you listed were string instruments, so I suppose you need those).
Depending on what you need it for, you can opt for another solution. What do you need it for and what demands do you have?
Buzz (above post) is nice for arranging mucical compositions in a simple “I’m no musician” way all the way up to semi-pro. I think there’s a forum where you can download patches for other instruments people have created. (I just downloaded this program, too.) If you’re Mac, I think Pro Tools Free is available, but not Windows XP. (google it.)
Another nice open-source program is Audacity: http://audacity.sourceforge.net/
This isn’t an arranging program, but more of a recording program. You can record (via microphone or internal sound card), which means you could pick up a CD, record sounds you like, and arrange them. The program saves to .mp3, .ogg, and .wav
Yeah, I learned about it from the “Complete Idiot’s Guide to Home Recording” by Clayton Walnum. (That title probably doesn’t translate well to non-native english speakers, does it?:rolleyes: ) Pro Tools is the so-called “grandaddy” of entire-recording-studio-in-a-computer software. Pick up the book at your local library, the open-source equivalent of Amazon!
In other news: I just learned that Audacity is able to capture and record streaming internet radio…now THERE"S some open-source for you.
It can also capture a MIDI file playing through your soundcard (True for Windows, might want to try it in linux or OSx) so perhaps that plus a MIDI composing tool is what you’re looking for. I remember a MIDI tool that has a community edition for free download somewhere. I think it was called Digital Audio Planet or some such. Google time.
There is decent software to do this (and sounds good too)
IIRC, Jan Morgenstern used Reaktor it in Elephants Dream, but it wasn’t open source: http://en.wikipedia.org/wiki/Reaktor.
There is another app which creates realistic orchestral effects, but I can’t remember what the name of it is
You could be able to just scrape by with digital instruments at a budget price with Garageband (mac only)
Not sure what OS you use, but for linux Alsa Modular Synth is a pretty amazing synthesizer - you make “instruments” by virtually hooking up oscillators to filters / amplifiers etc. http://alsamodular.sourceforge.net/
I use a number of different programs, including buzz, and audacity, but one of my favorites is called ‘axs’. it’s a bit quirky, but once you figure it out, it’s quite easy to use, and one benefit of it, is, when you’ve made your composition, it writes the wav file directly to the hard drive, so there’s not even a hint of a glitch. It gets no cleaner, no purer, than that. Also, you can load a single sample into it, and tell it to fill out the octave above or below, which is quite handy.