Re: [Denemo-devel] MIDI out

[Richard Shann]

On Mon, 2009-01-05 at 13:19 -0600, Jeremiah Benham wrote:
> On Mon, 2009-01-05 at 18:37 +0000, Richard Shann wrote:
> > On Mon, 2009-01-05 at 19:03 +0100, Nils Gey wrote:
> > > You could use just one Jack-port. this port has 16 midi channels anyway, 
> > > so for them its important that they could be chosen per staff (of course 
> > > multiple staffs could go into one channel).
> > > 
> > > That would be sufficent to route to one output or to several outputs at 
> > > once. To route to different outputs Denemo must be able to create several 
> > > different midi-out ports by the user, if needed.
> > > 
> > > Not far away from this topic is the bank/program select. Of course one 
> > > channel can only use one midi-bank, but the bank can be changed with the 
> > > specific midi-command. So a staff also should have an optional "choose 
> > > bank" entry and a midi-command-object to enter at any place in the staff 
> > > itself "change bank" is needed. Of course a standard-bank is only a 
> > > comfort-function for people who are too lazy to enter a "change bank" 
> > > right at the start.
> > > 
> > > But most samplers don't want the program/bank and run fine without it. 
> > > Its a more complex step.
> > > 
> > > I'm not a Dev but I think this is too much for the next release, at least 
> > > if it should be over an experimental status.
> > > 
> > 
> > Yes definitely 0.8.4 release, if someone will do it, we need to get
> > 0.8.2 out now - I'm just tidying the menus which have been annoying me
> > for a while.
> 
> Ok. Do you want me to wait until you are satisfied with the menus before
> I create a tarball?
Yes, wait just a bit, as I have seen a bit more clearly what to do,
having slept on yesterday's efforts. In particular I think I understand
what we should be doing with the two sorts of LilyPond insert things (at
long last).
Richard

> 
> Jeremiah 
> 
> 
> > Richard
> > 
> > > Nils
> > > 
> > > On Mon, 05 Jan 2009 11:33:47 -0600
> > > Jeremiah Benham <address@hidden> wrote:
> > > 
> > > > On Mon, 2009-01-05 at 09:52 +0000, Richard Shann wrote:
> > > > > There has been some chat on freenode#denemo with Nils and others about
> > > > > what the MIDI out (that has so many votes in the denemo poll) actually
> > > > > means.
> > > > > For those not there and to summarize what I have understood here are
> > > > > some thoughts:
> > > > > 
> > > > > Just putting out a MIDI note to a libjack output connection in place 
> > > > > of
> > > > > the playnotes which currently goes to the /dev/sequencer or to 
> > > > > portaudio
> > > > > is not what is being talked about.
> > > > > 
> > > > > What is meant is (at a minimum) to be able to point to a place in the
> > > > > score and have denemo promptly start outputting MIDI to libjack. The
> > > > > MIDI events it would output would correspond to the notes from the
> > > > > pointed place onwards in the score, including the prevailing
> > > > > dynamic/crescendo, midi instrument/channel (anything else? - embedded
> > > > > MIDI commands I guess). Notes that are hanging on at the given point
> > > > > would not be sounded (so if the given point just contained notes tied
> > > > > from previous notes, nothing would be heard until a new note started).
> > > > > The tempo would be a prevailing tempo at the note concerned (so we 
> > > > > would
> > > > > allow an embedded MIDI command that would change the tempo).
> > > > > 
> > > > > The actual jackmidi connection is trivial, of course, and someone on
> > > > > #denemo came up with a sample
> > > > > http://trac.jackaudio.org/browser/trunk/jack/example-clients/midiseq.c
> > > > > which shows how to do that.
> > > > > It is not intended that the user should be allowed to edit the score
> > > > > while it is being played. So the value of the gui->changecount 
> > > > > variable
> > > > > is fixed for any given playback.
> > > > 
> > > > Would we have one output jack port for each staff or would we mash it
> > > > all into to one jack port?  If each staff is assigned a different port
> > > > (which I am assuming is what people want) when would the initialization
> > > > of that port take place? During staff creation time? It could not be
> > > > just before playback because the I assume the users would want to assign
> > > > the created jack ports to various soft synths. I guess I am just kind of
> > > > hung up here on the UI and where to implement it.
> > > > 
> > > > Would this feature be for this release or next? 
> > > > 
> > > > Jeremiah
> > > > 
> > > > > 
> > > > > What would require a little design is how to create the MIDI events 
> > > > > from
> > > > > the denemo data. I think I have a good idea how to do this:
> > > > > An initialization stage would be good, partly to avoid excessive
> > > > > computation while playing & also for convenience of coding. So if this
> > > > > MIDI output system has not been initialized since the last edit to the
> > > > > score the first thing that happens is INITIALIZATION: this creates a
> > > > > list of MIDI events, with links from the notes in the score to first
> > > > > event that that note triggers. (As mentioned notes that are tied to
> > > > > earlier notes have no MIDI event).
> > > > > On requesting playback from a given note, the MIDI events are simply
> > > > > shovelled out to jackmidi.
> > > > > There are some extras that are easily incorporated - silencing staffs
> > > > > etc. but the real work is the INITIALIZATION task.
> > > > > 
> > > > > I think it can be done as follows:
> > > > >       INITIALIZATION: run a special version of exportmidi.c which 
> > > > > instead of
> > > > > writing to a file creates a list (GList* midi_events in the 
> > > > > DenemoScore
> > > > > structure) of MIDI events, putting a link from each note (etc) to the
> > > > > MIDI event which it causes.
> > > > > 
> > > > > To determine if INTIALIZATION is needed, we need to set a variable
> > > > > (gui->midichangecount) that is set to the gui->changecount when
> > > > > INITIALIZATION is run, so that if the comparison
> > > > > midichangecount==changecount fails when the play request is received 
> > > > > we
> > > > > know INITIALIZATION is needed again.
> > > > > 
> > > > > As Nils noticed, exportmidi has at least one bug (dynamics) which I 
> > > > > have
> > > > > put in the bug tracker.
> > > > > 
> > > > > I hope I have convinced someone that they could afford to devote an
> > > > > afternoon to implementing this.
> > > > > 
> > > > > Richard
> > > > > 
> > > > > 
> > > > > 
> > > > > 
> > > > > 
> > > > > 
> > > > > 
> > > > > 
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> > > > 
> > > > 
> > > > 
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