1. getTimeInfo() does *not* take a time argument of any kind; only a 32 bit filter, to say which fields you actually need. That is, you can only get the full info for the start of the buffer. There is a tempoAt() call, that gives you the tempo at the specified sample frame in the buffer. 2. The VstTimeInfo struct is interesting. I like the unit for musical time: pulses with 1 PPQN. :-) Tempo is in BPM. (Why not QN/s? ;-) There is a field that says where the last bar starts. There's also time signature, SMPTE, MIDI clock (samples to next clock) and a bunch of flags. Flags include transport changed, playing and "cycle active". (The latter come with loop start and end positions, obviously.) And automation reading + writing... It is also interesting to note that the "sample position" field in here is timeline bound - it may jump! There's a nanoseconds field as well, holding the "system time" corresponding to the first sample in the buffer. Conclusion: a. The information is there, but you have to *pull* it from the host. Doesn't seem like you're ever notified about tempo changes or transport events. b. Since you're asking the host, and there are no other arguments, there is no way that one plugin can keep track of more than one timeline. It seems that it is assumed that there is only one timeline in a net. 3. There are calls that allow plugins to get the audio input and output latency. Conclusion: c. I'm assuming that this is mostly useful for VU-meters and other stuff that needs to be delayed appropriately for correct display. Obviously not an issue when the audio latency is significantly shorter than the duration of one video frame on the monitor! ;-) Seriously though, this is needed for "high latency" applications to display meters and stuff correctly. They're not very helpful if they're half a second early! 4. There is a feature that allows plugins to tell the host which "category" they would fit in. (There is some enumeration for that somewhere.) Might be rather handy when you have a large number of plugins installed... 5. A getCurrentProcessLevel() host call lets the plugin ask what kind of context it's being called from. Can return values corresponding to "not supported", "user/GUI", "audio/irq", "sqeuncer/irq" and "user/offline". Other values are possible and "probably" (as they say) mean something that pre-empts the user thread. 6. There is support for using the whole process() call asynchronously. This is for external DSPs and stuff. The plugin is expected to return "instantly" from process(), and then the host wanders off to do something else. The host will use another plugin call to poll, to see if the data from the external DSP (or whatever) is available. Conclusion: d. I think we can ignore this feature. We don't do external DSP, and we don't feel like having hosts poll/busy-wait for data, do we...? 7. There's a bunch of calls specifically meant for off-line processing. This is basically about accessing the host's "open" files, setting markers and stuff, being notified when files are opened, closed, changed, when markers are changed etc. A plugin API in itself. 8. You can ask the host about the speaker arrangement, for surround stuff... 9. There is a bypass feature, so that hosts can have plugins implement sensible bypass for mono -> surround and other non-obvious in/out relations. (As if in/out relations ever were to be assumed "obvious"!) 10.Finally, the states. There are 2 calls related to this; suspend() and resume(). Nothing much is said about these, and they're not used for much in the examples. Just for clearing delay buffers and the like. Memory is generally allocated in the constructors and freed in the destructors, but I'm not sure when and where you're supposed to reallocate buffers if you need to... (This is when you start realizing why compatibility problems with VST are so common. Where are the reference docs!? *heh*) //David Olofson - Programmer, Composer, Open Source Advocate .- The Return of Audiality! --------------------------------. | Free/Open Source Audio Engine for use in Games or Studio. | | RT and off-line synth. Scripting. Sample accurate timing. | `---------------------------> http://olofson.net/audiality -' .- M A I A -------------------------------------------------. | The Multimedia Application Integration Architecture | `----------------------------> http://www.linuxdj.com/maia -' --- http://olofson.net --- http://www.reologica.se ---