Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On Wed, 2012-05-30 at 10:20 +0200, Albert Graef wrote: > On 05/29/2012 07:57 PM, David Robillard wrote: > > tl;dr: The state that needs to be reset is state that depends on a > > continuous stream of audio. Midi controllers and such do not cause > > problems if they persist across audio gaps, and are not what was being > > referred to here. > > Exactly. In the case of an instrument plugin, that might mean, e.g., > that the allocated voices and the pitch bends are reset, but usually not > the controllers. Incidentally, that's exactly how I implemented those > callbacks in faust-lv2, and it works nicely with Qtractor at least. Right. I think time is the key to explaining this clearly/precisely/generically. What's happening is that time is no longer continuous. Reset accordingly. -dr ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On 05/30/2012 11:20 AM, Paul Davis wrote: > again, you do not deactivate or in anyway change the execution of a > plugin simply in order to hear a "dry" signal. if you doubt this, just > turn the switch between "wet" and "dry" into a knob ... Ok, point taken, they're different things. -- Dr. Albert Gr"af Dept. of Music-Informatics, University of Mainz, Germany Email: dr.gr...@t-online.de, a...@muwiinfa.geschichte.uni-mainz.de WWW:http://www.musikinformatik.uni-mainz.de/ag ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On Wed, May 30, 2012 at 3:52 AM, Albert Graef wrote: > On 05/29/2012 07:39 PM, David Robillard wrote: > > In particular, for live plugins, you *have* to regularly call run if it > > is activated. So, to bypass, you're either running it on nothing > > (wasting cycles) or you have to deactivate it. > > Exactly. So Qtractor does in fact do the right thing there. :) Whether > you call that option Bypass or Activate in the GUI, I don't really care. > again, you do not deactivate or in anyway change the execution of a plugin simply in order to hear a "dry" signal. if you doubt this, just turn the switch between "wet" and "dry" into a knob ... ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On 05/29/2012 07:57 PM, David Robillard wrote: > tl;dr: The state that needs to be reset is state that depends on a > continuous stream of audio. Midi controllers and such do not cause > problems if they persist across audio gaps, and are not what was being > referred to here. Exactly. In the case of an instrument plugin, that might mean, e.g., that the allocated voices and the pitch bends are reset, but usually not the controllers. Incidentally, that's exactly how I implemented those callbacks in faust-lv2, and it works nicely with Qtractor at least. Paul, you said that Ardour doesn't do activate()/deactivate() with effect plugins. Is that the same with instrument plugins? Then the scheme I used in faust-lv2 probably doesn't fare that well with Ardour3, unless it takes care of resetting the plugin in some other way. -- Dr. Albert Gr"af Dept. of Music-Informatics, University of Mainz, Germany Email: dr.gr...@t-online.de, a...@muwiinfa.geschichte.uni-mainz.de WWW:http://www.musikinformatik.uni-mainz.de/ag ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On 05/29/2012 07:39 PM, David Robillard wrote: > In particular, for live plugins, you *have* to regularly call run if it > is activated. So, to bypass, you're either running it on nothing > (wasting cycles) or you have to deactivate it. Exactly. So Qtractor does in fact do the right thing there. :) Whether you call that option Bypass or Activate in the GUI, I don't really care. -- Dr. Albert Gr"af Dept. of Music-Informatics, University of Mainz, Germany Email: dr.gr...@t-online.de, a...@muwiinfa.geschichte.uni-mainz.de WWW:http://www.musikinformatik.uni-mainz.de/ag ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On Tue, 2012-05-29 at 21:51 +, Fons Adriaensen wrote: > On Mon, May 28, 2012 at 10:49:06PM -0400, David Robillard wrote: > > > > I'd say that the standard case here is to *keep* all the MIDI controller > > > settings, not reset them. Just imagine that you're running a reverb > > > which forgets all settings when you briefly deactivate it in order to > > > listen to the dry signal. That would essentially render such a plugin > > > totally useless. Or am I missing something here? > > > > It does seem like the most reasonable thing to do. > > I agree. > > This issue raises some other questions on how plugins could/should > handle MIDI input. I offer the following for your consideration and > comments. > > The four cases outlined below are in fact points on a continuous > scale, with (1) and (4) being the extremes. The interesting range > is between (2) and (3). > > 1. The host accepts MIDI input, selects on port, channel, controller > number (e.g. by providing a 'learn' function), and converts selected > messages to control port values. The plugins are never aware that their > input is from MIDI. > > 2. As above, but the selected data is presented to the plugin either > in MIDI format, or via some more generic 'event delivery' mechanism. > The difference with (1) is that the plugin knows it is dealing with > events. > > 3. The host provides the MIDI ports, but offers all it gets to any > interested plugin. The plugin performs selection on port, channel > and controller number. > > 4. The plugin provides its own MIDI input, completely independent > from the host. LV2 takes the simple non-choice strategy that Jack *really* should have also went with: you can have inputs and outputs that are a buffer of time-stamped events with *whatever* in them. In practice, this has been only really been used for MIDI until recently. Now more 'high level' things (like loading samples) are starting to be done using non-MIDI events (e.g. LV2 'atoms' which is sort of a binary JSON-like thing). Firing around POD-blobs of whatever is fantastic. While I would like to see something better than MIDI get established for notes and such, no interest there so far. Unsurprisingly I don't think the core API should be burdened with all that. > Some initial comments: > > * One could argue that (3) and (4) lead to a lot of non-trivial > code and development effort being duplicated or repeated for > each plugin. But that need no be the case: the plugin SDK could > offer services that would make this (almost) as easy for the > plugin developer as (1) or (2). > > * In (1,2) the selection of port/channel/controller are part of > the host configuration, this data would normally be stored in > the host's session file and the plugins are never aware of it. > In (3,4), the selection criteria become part of the plugin's > configuration, and could be included in e.g. plugin presets. > That makes a difference for the user - but I'm uncertain as > to which would be best. I doubt any strong conclusion could be reached either way. The thing is, there are all kinds of good reasons for plugins to want to process streams of MIDI (or OSC, or...) events. Even if there was an alternative somewhat equivalent system for it, this would be true. Something better than MIDI would be great, but not supporting MIDI would surely doom any plugin API. Better to support and let somebody pioneer a better alternative when they're actually going to get around to doing something with it (we can't really afford to be idealist on this one anyway, the lack of LAD synth plugins is bad enough without adding that gigantic barrier to porting on top of it) For example, a great Ardour project would be to support explicit note control (e.g. the ability to draw a single note and pitch bend it as an arbitrary vector, and apply controls to *that note alone*) and actually send all that data to a synth plugin (which MIDI can not do, OSC could, other options as well) would be a great project. A chicken & egg situation, though, that could only be resolved by someone actually setting out to make that happen. Hopefully some day they do. > * I'd expect (1,2) for e.g. individual modular synth modules, > it would feel strange if each individual one would implement > (3,4). OTOH, it wouldn't feel so odd if e.g. a Linuxsampler > or Yoshimi plugin would do that. [*] Modulars can conveniently get around it by having separate plugins to do whatever filtering the user wants. Probably the only "truly modular" way to do it, really. Stuff like LinuxSampler and Yoshimi are good examples of large fully featured things that exist, and though existing code is troublesome/irritating in an endless number of ways, I think practically speaking it's clear this stuff has to work. > * My tentative conclusion would be that a plugin standard > should provide both (2) and (3), and maybe something in > between those. Thus far, 'the market' agrees, so that's probably the right con
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On Tue, 2012-05-29 at 16:18 +, Fons Adriaensen wrote: > On Tue, May 29, 2012 at 09:48:10AM -0400, Paul Davis wrote: > > > the question really is under what circumstances should the host/user call > > deactivate/activate? > > > > if the host/user has done this, then they should be clear on the > > consequences. you don't call these functions in order to bypass a plugin. > > you call them specifically when there is a need to completely reset the > > state of the plugin. > > I've always lookat at activate() as part of the sequence > required to load a plugin and make it work, not as something > ever explicitly done by the user. If a plugin needs a 'Reset' > (some do, it depends on the particular effect), it should have > a Reset button. > > Since in LV2 activate() and deactivate() do not affect port > connections, I'd say they should not reset any controller > values that the plugin gets from MIDI input. The controller > remains connected, but it doesn't know it should resend its > current value if the plugin would reset it. This is a digression, but I think port_connect() is the dumbest thing in LV2. I have all sorts of plugins that would be stateless but for the idiotic need to keep that stuff around, when they are only used in run anyway. All that function calling is also expensive, most hosts I have seen just end up connecting every port every cycle anyway. It's absurd. Should be arrays of buffer pointers to run(). > AFAICS, Ardour's 'activate' and 'deactivate' (at least for > LADSPA plugins) do not call those functions, they just change > the signal routing. Which looks to me as the right thing. It's the rightest thing, but it also wastes cycles. > Another questions if a host bypasses a plugin, should it still > provide input signals to the plugin and run its process() ? For live plugins it is strictly required to, for non-live plugins it is not. Since we don't actually have stateless plugins at all (thanks to the above connect_port mistake) activate and deactivate are essentially 'start time' and 'stop time'. Whenever the time of data processed by subsequent calls to run() is not contiguous (e.g. a transport locate) the plugin MUST be deactivated and reactivated again. In other words, if you havn't been deactivated, the audio you are receiving in subsequent run calls is a continuous stream of audio. Otherwise you'll end up applying 'trends' (like parameter interpolation) from the 'previous' (but not) block to the current one, which is wrong. This guarantee is necessary to be able to do basic stuff like filters correctly. I think it is the actual motivation for the 'activate resets state' language (e.g. you must reset your filter state because there's been a gap in audio), but this should probably be clarified. Nothing in the spec lays out this 'continuous stream' thing clearly. tl;dr: The state that needs to be reset is state that depends on a continuous stream of audio. Midi controllers and such do not cause problems if they persist across audio gaps, and are not what was being referred to here. -dr ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On Tue, 2012-05-29 at 09:48 -0400, Paul Davis wrote: [...] > you really want both (a) a method to stop and restart the plugin (b) a > method to reset to it back to the state it would have immediately > after instantiation. its not 100% whether deactivate/activate is > either of these ... There is also the distinction between "live" plugins and non-live plugins (plugins can indicate being live and there are rules about it. In particular, for live plugins, you *have* to regularly call run if it is activated. So, to bypass, you're either running it on nothing (wasting cycles) or you have to deactivate it. -dr ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On Mon, May 28, 2012 at 10:49:06PM -0400, David Robillard wrote: > > I'd say that the standard case here is to *keep* all the MIDI controller > > settings, not reset them. Just imagine that you're running a reverb > > which forgets all settings when you briefly deactivate it in order to > > listen to the dry signal. That would essentially render such a plugin > > totally useless. Or am I missing something here? > > It does seem like the most reasonable thing to do. I agree. This issue raises some other questions on how plugins could/should handle MIDI input. I offer the following for your consideration and comments. The four cases outlined below are in fact points on a continuous scale, with (1) and (4) being the extremes. The interesting range is between (2) and (3). 1. The host accepts MIDI input, selects on port, channel, controller number (e.g. by providing a 'learn' function), and converts selected messages to control port values. The plugins are never aware that their input is from MIDI. 2. As above, but the selected data is presented to the plugin either in MIDI format, or via some more generic 'event delivery' mechanism. The difference with (1) is that the plugin knows it is dealing with events. 3. The host provides the MIDI ports, but offers all it gets to any interested plugin. The plugin performs selection on port, channel and controller number. 4. The plugin provides its own MIDI input, completely independent from the host. Some initial comments: * One could argue that (3) and (4) lead to a lot of non-trivial code and development effort being duplicated or repeated for each plugin. But that need no be the case: the plugin SDK could offer services that would make this (almost) as easy for the plugin developer as (1) or (2). * In (1,2) the selection of port/channel/controller are part of the host configuration, this data would normally be stored in the host's session file and the plugins are never aware of it. In (3,4), the selection criteria become part of the plugin's configuration, and could be included in e.g. plugin presets. That makes a difference for the user - but I'm uncertain as to which would be best. * I'd expect (1,2) for e.g. individual modular synth modules, it would feel strange if each individual one would implement (3,4). OTOH, it wouldn't feel so odd if e.g. a Linuxsampler or Yoshimi plugin would do that. [*] * My tentative conclusion would be that a plugin standard should provide both (2) and (3), and maybe something in between those. Comments invited ! [*] Some tricky questions to disturb your sleep: We now have a few plugins that are in fact complete multitimbral instruments. Suppose someone would first add LV2 support to AMS (it can use plugins as if they were native modules), then turn the complete AMS itself into an LV2 plugin. - Should AMS then be able to load itself ??? - What impact would that have on the things discussed above ??? Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow) ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On Tue, May 29, 2012 at 09:48:10AM -0400, Paul Davis wrote: > the question really is under what circumstances should the host/user call > deactivate/activate? > > if the host/user has done this, then they should be clear on the > consequences. you don't call these functions in order to bypass a plugin. > you call them specifically when there is a need to completely reset the > state of the plugin. I've always lookat at activate() as part of the sequence required to load a plugin and make it work, not as something ever explicitly done by the user. If a plugin needs a 'Reset' (some do, it depends on the particular effect), it should have a Reset button. Since in LV2 activate() and deactivate() do not affect port connections, I'd say they should not reset any controller values that the plugin gets from MIDI input. The controller remains connected, but it doesn't know it should resend its current value if the plugin would reset it. AFAICS, Ardour's 'activate' and 'deactivate' (at least for LADSPA plugins) do not call those functions, they just change the signal routing. Which looks to me as the right thing. Another questions if a host bypasses a plugin, should it still provide input signals to the plugin and run its process() ? I tend to say yes - it's what you usually get on real mixers when patching an outboard processor, and it can be useful in some cases when working 'life', e.g. to set up a dynamics processor (which requires input) before inserting it. Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow) ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On 2012-05-29 14:37, Albert Graef wrote: On 05/29/2012 02:23 PM, Paul Davis wrote: there's a misconception right there, i think. you wouldn't deactivate it to listen to the dry signal. you'd bypass it using some feature of the host. Yes, of course this depends on the host. But presumably an LV2 host would then also deactivate the plugin and later reactivate it to reset it to a sane state? At least that's what I thought these callbacks were for. IIRC that's how it works in Qtractor (Rui, please correct me if I'm wrong), and that certainly makes sense to me. I didn't test this with Ardour, though. aha. qtractor doesn't have this "bypass" option as Paul refers to (i guess from ardour's;) as being independent of lv2 deactivate()/activate() calls... fact is, qtractor does call lv2plug.in->activate()/deactivate() respectively, whenever its own plugin "activate"/"deactivate" commands are issued, or the equivalent for other plugin types (vst, ladspa, dssi. altough neither of which resets qtractor's external midi controllers assignments per se... however, depending on plugins implementation, it might (yeah might) reset a plugins internal state re. their eventual midi control state, leaving the host, qtractor in particular, to play catch-up after every deactivate/activate() cycle... yeah. you might have a point in there ;) maybe it's all qtractor fault, of not having a separate "bypass" switch independent of plugins (de)activate/activate() sort of power-cycle... hmm... thinking of it, my recent "vee one" proto-toys (synthv1 & samplv1) actually rest their midi control state upon lv2::(de)activate() ... that is, they behave as if a "panic" button has been issued especially the all-controllers-off one (ie. GM CC#121) ... so, should i read this whole question about a case of lv2 plugin implementation or is that a lack of simple "bypass" on qtractor (or any other lv2 host) to be at stake ? cheers -- rncbc aka. Rui Nuno Capela ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On Tue, May 29, 2012 at 9:37 AM, Albert Graef wrote: > On 05/29/2012 02:23 PM, Paul Davis wrote: > > there's a misconception right there, i think. you wouldn't deactivate it > > to listen to the dry signal. you'd bypass it using some feature of the > > host. > > Yes, of course this depends on the host. But presumably an LV2 host > would then also deactivate the plugin and later reactivate it to reset > it to a sane state? At least that's what I thought these callbacks were > for. IIRC that's how it works in Qtractor (Rui, please correct me if I'm > wrong), and that certainly makes sense to me. I didn't test this with > Ardour, though. > > Otherwise, how is an LV2 plugin supposed to know that it has been > suspended and should prepare its internal state to be switched back on > again? All the host knows about the plugin are its ports, so it's > limited in what it can do. Only the plugin itself knows about the extra > cleanup it might want to do when being switched off and then back on > again, no? > the question really is under what circumstances should the host/user call deactivate/activate? if the host/user has done this, then they should be clear on the consequences. you don't call these functions in order to bypass a plugin. you call them specifically when there is a need to completely reset the state of the plugin. however, david's point stands which is that you really want both (a) a method to stop and restart the plugin (b) a method to reset to it back to the state it would have immediately after instantiation. its not 100% whether deactivate/activate is either of these ... ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On 05/29/2012 02:23 PM, Paul Davis wrote: > there's a misconception right there, i think. you wouldn't deactivate it > to listen to the dry signal. you'd bypass it using some feature of the > host. Yes, of course this depends on the host. But presumably an LV2 host would then also deactivate the plugin and later reactivate it to reset it to a sane state? At least that's what I thought these callbacks were for. IIRC that's how it works in Qtractor (Rui, please correct me if I'm wrong), and that certainly makes sense to me. I didn't test this with Ardour, though. Otherwise, how is an LV2 plugin supposed to know that it has been suspended and should prepare its internal state to be switched back on again? All the host knows about the plugin are its ports, so it's limited in what it can do. Only the plugin itself knows about the extra cleanup it might want to do when being switched off and then back on again, no? -- Dr. Albert Gr"af Dept. of Music-Informatics, University of Mainz, Germany Email: dr.gr...@t-online.de, a...@muwiinfa.geschichte.uni-mainz.de WWW:http://www.musikinformatik.uni-mainz.de/ag ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On Mon, May 28, 2012 at 10:49 PM, David Robillard wrote: > On Tue, 2012-05-29 at 01:43 +0200, Albert Graef wrote: > > On 05/28/2012 07:27 PM, David Robillard wrote: > > > For live plugins if you're going to stop continually running the > plugin, > > > you must deactivate it, so I can see how a complete and total state > > > reset here might be undesirable. I'm not sure. A complete > > > cleanup/re-initialization is always an option for a total reset, though > > > of course not real-time whatsoever. > > > > I'd say that the standard case here is to *keep* all the MIDI controller > > settings, not reset them. Just imagine that you're running a reverb > > which forgets all settings when you briefly deactivate it in order to > > listen to the dry signal. > there's a misconception right there, i think. you wouldn't deactivate it to listen to the dry signal. you'd bypass it using some feature of the host. ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On Tue, 2012-05-29 at 01:43 +0200, Albert Graef wrote: > On 05/28/2012 07:27 PM, David Robillard wrote: > > For live plugins if you're going to stop continually running the plugin, > > you must deactivate it, so I can see how a complete and total state > > reset here might be undesirable. I'm not sure. A complete > > cleanup/re-initialization is always an option for a total reset, though > > of course not real-time whatsoever. > > I'd say that the standard case here is to *keep* all the MIDI controller > settings, not reset them. Just imagine that you're running a reverb > which forgets all settings when you briefly deactivate it in order to > listen to the dry signal. That would essentially render such a plugin > totally useless. Or am I missing something here? It does seem like the most reasonable thing to do. I don't know what the wording should be changed to, then. Perhaps all that is reset between deactivate() and activate() is everything that is time dependent? Note that doing this means there is no way for the host to reset a plugin instance to a known state other than completely reinstantiating it. I don't know if this is a bad thing (since that's the only way you can really be sure anyway) -dr ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On 05/28/2012 07:27 PM, David Robillard wrote: > For live plugins if you're going to stop continually running the plugin, > you must deactivate it, so I can see how a complete and total state > reset here might be undesirable. I'm not sure. A complete > cleanup/re-initialization is always an option for a total reset, though > of course not real-time whatsoever. I'd say that the standard case here is to *keep* all the MIDI controller settings, not reset them. Just imagine that you're running a reverb which forgets all settings when you briefly deactivate it in order to listen to the dry signal. That would essentially render such a plugin totally useless. Or am I missing something here? -- Dr. Albert Gr"af Dept. of Music-Informatics, University of Mainz, Germany Email: dr.gr...@t-online.de, a...@muwiinfa.geschichte.uni-mainz.de WWW:http://www.musikinformatik.uni-mainz.de/ag ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
On Mon, 2012-05-28 at 18:41 +0300, Stefano D'Angelo wrote: > 2012/5/25 Jeremy Salwen : > > Hi all, > > > > The LV2 spec says that on a call to activate(), "the plugin instance MUST > > reset all state information dependent on the history of the plugin instance > > except for any data locations provided by connect_port()" > > > > I am not certain whether MIDI CC parameters are included in this category of > > "data locations provided by connect_port()". The CC parameters are sent > > through port buffers provided by connect_port(), but because they are event > > buffers, all information passed through them is necessarily part of the > > history of the plugin instance. > > > > I could imagine cases where you would want to reset all internal state of > > the plugin, but since CC values are very much like port values, they would > > be kept. On the other hand, I could also imagine cases where you would want > > to reset all internal data including the CC parameters. > > > > I'm assuming MIDI note on/off status certainly should be reset. > > > > I have always interpreted activate()/deactivate() as a real-time safe > alternative to instantiate()/cleanup(), so I'd say restart fresh, wipe > out everything. > > I do not necessarily agree that MIDI CC is like a port value, since > when the first run() after the first activate() is called and there's > no incoming CC event, however you probably need to be in a certain > "initial state". > > The spec explicitly states: "the plugin instance MUST reset all state information dependent on the history of the plugin instance except for any data locations provided by connect_port()" This text does date from a time when that was the only way to actually get any data in/out of a plugin, so it might need clarification now with MIDI/other events/state/etc. For live plugins if you're going to stop continually running the plugin, you must deactivate it, so I can see how a complete and total state reset here might be undesirable. I'm not sure. A complete cleanup/re-initialization is always an option for a total reset, though of course not real-time whatsoever. > Concrete use case would help. Indeed. -dr ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Should LV2 Activate() clear MIDI CC parameters?
2012/5/25 Jeremy Salwen : > Hi all, > > The LV2 spec says that on a call to activate(), "the plugin instance MUST > reset all state information dependent on the history of the plugin instance > except for any data locations provided by connect_port()" > > I am not certain whether MIDI CC parameters are included in this category of > "data locations provided by connect_port()". The CC parameters are sent > through port buffers provided by connect_port(), but because they are event > buffers, all information passed through them is necessarily part of the > history of the plugin instance. > > I could imagine cases where you would want to reset all internal state of > the plugin, but since CC values are very much like port values, they would > be kept. On the other hand, I could also imagine cases where you would want > to reset all internal data including the CC parameters. > > I'm assuming MIDI note on/off status certainly should be reset. I have always interpreted activate()/deactivate() as a real-time safe alternative to instantiate()/cleanup(), so I'd say restart fresh, wipe out everything. I do not necessarily agree that MIDI CC is like a port value, since when the first run() after the first activate() is called and there's no incoming CC event, however you probably need to be in a certain "initial state". Concrete use case would help. Stefano ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
