[music-dsp] Hosting playback module for samples
I realize that this is slightly off the beaten path for this group, but it's a problem that I've been trying to solve for a few years: I had written software for notation-based composition and playback of orchestral scores. That was done via MIDI. I was working on porting the original C++ to C#, and everything went well...except for playback. The world has changed from MIDI-based rack-mount samplers to computer- based samples played back via hosted VSTi's. And unfortunately, hosting a VSTi is another world of involved software development, even with unmanaged C++ code. Hosting with managed code (C#) should be possible, but I don't think it has been done yet. So I'm stuck. I've spoken to Marc Jacobi, who has a managed wrapper for VST C++ code, but VSTi hosting is still not that simple. Marc is very helpful and generous, and I pester him once a year, but it remains an elusive problem. It occurred to me that one of the resourceful people here may have ideas for working around this. What I'm looking for, short term, is simply a way to play back orchestral samples or even guitar/bass/drums as a way of testing my ported C# code. Ideally send note-on, velocity, note-off, similar to primitive MIDI. Continuous controller for volume would be icing. Any ideas, however abstract, would be greatly appreciated. MG NYC -- dupswapdrop -- the music-dsp mailing list and website: subscription info, FAQ, source code archive, list archive, book reviews, dsp links http://music.columbia.edu/cmc/music-dsp http://music.columbia.edu/mailman/listinfo/music-dsp
Re: [music-dsp] Hosting playback module for samples
1. Re: Hosting playback module for samples (Ross Bencina) From: Ross Bencina rossb-li...@audiomulch.com Hi Mark, I'm not really sure that I understand the problem. Can you be more specific about the problems that you're facing? Hi Ross, Specific: (Forgive me if you know all of this): My code is C#, but there is no simple way to bridge the gap between the managed realm and a module that can play orchestral samples. Most sample banks these days seem to be in NKI format (Native Instruments). They have the ability to map ranges of a keyboard into different samples so the timbres don't become munchkin-ized or Vader-ized. IOW, natural sound within each register. A playback engine is typically something like Native Instruments' Kontakt, which is 'hosted' by the main program (my composition software, for ex). then NI Kontakt can load up NKI files and deliver sound when it receives events. The whole process of linking events, etc is what usually what stymies programmers who are new to VST-based programming. And even many who are familiar. Personally I would avoid managed code for anything real-time (ducks). Actually, C# can be faster than pre-compiled code! The first time a given section of code runs, the JIT (just in time) compiler replaces the 'IL' code with highly optimized machine code. Since the JIT module can test the CPU that it running on, it can optimize for that particular CPU and chip set. Early on, one of the popular book authors (Richard Grimes) coded FFT algorithms in both C++ and C#, and C# was faster. You're need to build a simple audio engine (consider PortAudio or the ASIO SDK). And write some VSTi hosting code using the VST SDK. It's this last bit that will require some work. But if you limit yourself to a small number of supported plugins to begin with it should not be too hard. MIDI scheduling in a VSTi is not particularly challenging -- the plugins do the sub-buffer scheduling, you just need to put together a frame of MIDI events for each audio frame. That's inspiring. I'm not sure that this is done in the same way as a regular plugin though. And I believe it's pretty difficult to host a VSIi in managed code. That is pretty much the crux of the problem right there. I've heard of a lot of people who started the project but were never aboe to get it off te ground. If there's any kind of synchronisation with the outside world things will get trickier, but if you can clock the MIDI time off the accumulated sample position it's not hard. I could do without sync to external for now. ... I guess the main approaches would be to either (A) schedule MIDI events ahead of time from your C# code and use a priority queue (Knuth Heap is easy and relatively safe for real-time) in the audio thread to work out when to schedule them; or (B) maintain the whole MIDI sequence in a vector and just play through it from the audio thread. Then you need a mechanism to update the sequence when it changes (just swap in a new one?). The internals of a VSTi host are beyond me at present. I was hoping for some simple thing that could be accessed by sending MIDI-like events to a single queue. Thanks to both who responded. I've signed up for the PortAudio mailing list. Maybe they have something. Mark G. NYC -- dupswapdrop -- the music-dsp mailing list and website: subscription info, FAQ, source code archive, list archive, book reviews, dsp links http://music.columbia.edu/cmc/music-dsp http://music.columbia.edu/mailman/listinfo/music-dsp
