Fix MIDI loop recording.

This changes how things work a bit, but I am committing it for 3.0 since the
previous revision often crashed (and never worked), this one seems to work
fine, and the code is quite a bit more cogent.

I have tested the following use cases with live input and audible output:

 * Non-loop recording, armed before roll
 * Non-loop recording, arm while rolling
 * Loop recording, armed before roll
 * Loop recording, arm during roll

In the last case, the source/region is created starting at the loop start
rather than the current transport frame as usual so time makes sense when it
wraps around.

See the documentation added to the code for details, but the basic idea here is
to simply push MIDI events to the source with increasing monotonic time,
ignoring looping altogether.  Essentially we pretend the loop does not exist,
but the source knows all the details so it can implement whatever behaviour is
appropriate.

Currently, this is simply recording a complete non-destructive copy of the
input, which is a good thing.  Perhaps not what the user expects of loop
recording, but at least it works and is one sensible option.  We will need to
add more later.

Display while recording is a little bit wacky, but whatever.


git-svn-id: svn://localhost/ardour2/branches/3.0@13940 d708f5d6-7413-0410-9779-e7cbd77b26cf

1 files changed, 1 insertions, 0 deletions

diff --git a/libs/ardour/ardour/midi_diskstream.h b/libs/ardour/ardour/midi_diskstream.h
index 45ea975ea9..be0e0fe48c 100644
--- a/libs/ardour/ardour/midi_diskstream.h
+++ b/libs/ardour/ardour/midi_diskstream.h
@@ -195,6 +195,7 @@ class MidiDiskstream : public Diskstream
 	volatile gint                _frames_written_to_ringbuffer;
 	volatile gint                _frames_read_from_ringbuffer;
 	volatile gint                _frames_pending_write;
+	volatile gint                _num_captured_loops;
 
 	/** A buffer that we use to put newly-arrived MIDI data in for
 	    the GUI to read (so that it can update itself).