Hopefully fix dropped MIDI notes on loop. Fixes #3133.

git-svn-id: svn://localhost/ardour2/branches/3.0@7613 d708f5d6-7413-0410-9779-e7cbd77b26cf

diff --git a/libs/ardour/midi_diskstream.cc b/libs/ardour/midi_diskstream.cc
index 08b37193011cd604df5b025fcb53e4442811dd9a..3151869fc30438c8ebec21913ac53e61980de511 100644 (file)
--- a/libs/ardour/midi_diskstream.cc
+++ b/libs/ardour/midi_diskstream.cc
@@ -749,7 +749,7 @@ MidiDiskstream::read (nframes_t& start, nframes_t dur, bool reversed)
                        if (reloop) {
                                // Synthesize LoopEvent here, because the next events
                                // written will have non-monotonic timestamps.
-                               _playback_buf->write(loop_end - 1, LoopEventType, 0, 0);
+                               _playback_buf->write(loop_end - 1, LoopEventType, sizeof (nframes_t), (uint8_t *) &loop_start);
                                cout << "Pushing LoopEvent ts=" << loop_end-1
                                     << " start+this_read " << start+this_read << endl;
 

diff --git a/libs/ardour/midi_ring_buffer.cc b/libs/ardour/midi_ring_buffer.cc
index 2999621b70918d731be7b2517ff8dac685b9ad11..4c89cbcf4c1f24fced5707506b8f61519d35caa3 100644 (file)
--- a/libs/ardour/midi_ring_buffer.cc
+++ b/libs/ardour/midi_ring_buffer.cc
@@ -44,16 +44,44 @@ MidiRingBuffer<T>::read(MidiBuffer& dst, nframes_t start, nframes_t end, nframes
        Evoral::EventType ev_type;
        uint32_t          ev_size;
 
+       /* If we see the end of a loop during this read, we must write the events after it
+          to the MidiBuffer with adjusted times.  The situation is as follows:
+
+           session frames----------------------------->
+          
+                    |                            |                    |
+               start_of_loop                   start              end_of_loop
+
+          The MidiDiskstream::read method which will have happened before this checks for
+          loops ending, and helpfully inserts a magic LoopEvent into the ringbuffer.  After this,
+          the MidiDiskstream continues to write events with their proper session frame times,
+          so after the LoopEvent event times will go backwards (ie non-monotonically).
+
+          Once we hit end_of_loop, we need to fake it to make it look as though the loop has been
+          immediately repeated.  Say that an event E after the end_of_loop in the ringbuffer
+          has time E_t, which is a time in session frames.  Its offset from the start
+          of the loop will be E_t - start_of_loop.  Its `faked' time will therefore be
+          end_of_loop + E_t - start_of_loop.  And so its port-buffer-relative time (for
+          writing to the MidiBuffer) will be end_of_loop + E_t - start_of_loop - start.
+
+          The subtraction of start is already taken care of, so if we see a LoopEvent, we'll
+          set up loop_offset to equal end_of_loop - start_of_loop, so that given an event
+          time E_t in the ringbuffer we can get the port-buffer-relative time as
+          E_t + offset - start.
+       */
+
+       frameoffset_t loop_offset = 0;
+
        size_t count = 0;
 
        while (this->read_space() >= sizeof(T) + sizeof(Evoral::EventType) + sizeof(uint32_t)) {
 
                this->full_peek(sizeof(T), (uint8_t*)&ev_time);
 
-               if (ev_time >= end) {
+               if (ev_time + loop_offset >= end) {
                        DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("MRB event @ %1 past end @ %2\n", ev_time, end));
                        break;
-               } else if (ev_time < start) {
+               } else if (ev_time + loop_offset < start) {
                        DEBUG_TRACE (DEBUG::MidiDiskstreamIO, string_compose ("MRB event @ %1 before start @ %2\n", ev_time, start));
                        break;
                } else {
@@ -68,15 +96,18 @@ MidiRingBuffer<T>::read(MidiBuffer& dst, nframes_t start, nframes_t end, nframes
 
                // This event marks a loop end (i.e. the next event's timestamp will be non-monotonic)
                if (ev_type == LoopEventType) {
-                       /*ev_time -= start;
-                         ev_time += offset;*/
                        cerr << "MRB loop boundary @ " << ev_time << endl;
+                       
+                       assert (ev_size == sizeof (nframes_t));
+                       nframes_t loop_start;
+                       read_contents (ev_size, (uint8_t *) &loop_start);
 
-                       // Return without reading data or writing to buffer (loop events have no data)
-                       // FIXME: This is not correct, loses events after the loop this cycle
-                       return count + 1;
+                       loop_offset = ev_time - loop_start;
+                       continue;
                }
 
+               ev_time += loop_offset;
+
                uint8_t status;
                success = this->full_peek(sizeof(uint8_t), &status);
                assert(success); // If this failed, buffer is corrupt, all hope is lost
@@ -92,6 +123,7 @@ MidiRingBuffer<T>::read(MidiBuffer& dst, nframes_t start, nframes_t end, nframes
                }
 
                assert(ev_time >= start);
+               
                ev_time -= start;
                ev_time += offset;