skipped midi notes MIDI tracks (with Drum Instrument) don't play all 1/8 notes

[e2music@cox.net]

I created virtual instrument track for a simple part that plays nothing but 1/8 notes (960 PPQ, 4/4,  140 BPM but the error still occurs at different tempi).  The track does not play back all the events.  I tried using several different virtual drum instruments (Session Drummer 3, Cakewalk-SI-Drums, etc.) but the result is the same.  There is a pattern to the playback failures.  The failures only occur on certain upbeats (clock value of 480 ticks).  No other rhythm values (like the 1/16ths before or after the failed upbeats) are affected. The first 4 downbeats  and upbeats play correctly.  Then the upbeat after the first down beat of the next bar (i.e. -- the "and" of beat 1) does not play.  Then the next four beats (beat numbers 2, 3, 4, and 1 of the next bar) play correctly, but the upbeat following the next beat (the "and"  of beat 2) fails to play.  This error repeats with 4 good beats (downbeat numbers 3, 4 and 1 and 2 of the next bar) followed by a failure on the "and" of beat 3, etc.   Like so:

1 + 2 + 3 + 4 + | 1 +(fail) 2 + 3 + 4 + | 1 + 2 + 3 + 4 + |  1 + 2 +(fail) + 3 + 4 + | 1 + 2 + 3 + 4 + |  1 + 2 + 3 +(fail) 4 + | . . .

The MIDI events lengths are not overlapping.  I have deleted the Virtual Instrument track and recreated new ones using different drum instruments but the error occurs the same.  It does not matter which nor how many MIDI notes are scheduled to be played (1 MIDI note event fails just like having numerous simultaneous MIDI note events) on the upbeats that fail to play. This seems like a mathematical error in some algorithm that is causing the MIDI NoteOn command for those events to be ignored even though examination of the Midi Events shows no erroneous or missing entries .  This has become problematic and has required elaborate and unnecessarily complex rhythmic "camouflage" to cover up these playback failures.  I understand that sometimes latency with a specific virtual instrument or extremely complex rhythmic structures at high tempi can cause temporary dropouts while playing back MIDI data, but rendering the MIDI data through a virtual instrument to an Audio track or file usually fixes these errors because the audio rendering is not performed in real-time.  However, in this case, rendering the MIDI track to audio captures the errors.

Edited February 26, 2019 by e2music@cox.net

[scook]

Dropped MIDI notes may be the result of too low a Prepare Using: nnn Millisecond Buffers value. The default is 250, however; 500 or 750 often work better. Some use values as high as 10x the default.

[RBH]

I've encountered midi drum playback failures when the note durations were extremely short. This was using Battery on an older system though  But, maybe worth looking into.  I set duration's to at least 40 - 50 tics  - makes them easier to see in PRV as well. 

[e2music@cox.net]

@scook: Setting Preferences->MIDI->Playback and Recording->"Prepare Using: nnn Millisecond Buffers value" to 450 (was default 250) resolved the issue.  450 is the lowest value that resulted in consistent playback on my system. ?

Thanks!

Edited February 27, 2019 by e2music@cox.net
typo correction.