Here is a tutorial that I created a while back for a user who enquired privately on a problem he was having with successfully understanding and applying portamento. The MIDI files illustrate two different approaches to a particular portamento situation. The first file (Portamento test 1.mid) uses the combination of cc19 and cc20. The second file (Portamento test 2.mid) uses just cc20. These files require that you have applied the GPO update from last fall. The user who submitted this MIDI example was using it with solo violins. Here are the two MIDI files:
1. Portamento (cc20) only applies to the sustain pedal down (legato) position in the updated programming to GPO. Notice where I have placed the cc64 data.
2. In this case I am only using cc20 data for the transitions between 3rd and 4th notes. The transition between the 2nd and 3rd notes is handled with pitchbend data instead of portamento data. The cc19 layer (which does not respond to pitchbend) has been activated for the second note so that pitchbend data can be applied to the 3rd note without also potentially affecting the 2nd note - especially if there are note overlaps.
3. A small value piece of cc20 data has been applied to the position just before the 2nd note to neutralize the portamento direction. This allows the transitions between the 3rd and 4th notes to move in the correct direction.
4. I have added mod wheel data (cc1) to the file. Expressive mod wheel data should be present at all times to dynamically shape the passage.
The second file:
1. This uses only cc20 data (not cc19+pitchbend as in the first file).
2. Notice that the sustain pedal down data (cc64) is placed before the start of the second note. This results in a slightly different attack to the second note but allows the portamento to function properly (since it is confined to the legato layer).
3. A small value piece of cc20 data is placed after the cc64 data but prior to the start of the second note. This neutralizes the direction of the portamento so that transitions between the 2nd and 3rd notes playback properly.
4. I've used somewhat different mod wheel data on the second note compared to the first file. This is due to the differences in attack characteristics of the second note with sustain pedal applied.
On both files I have used relatively smaller cc20 values for larger intervals and larger cc20 values for smaller intervals. In these cases I have left the values somewhat exaggerated to clearly illustrate what was happening. In actual practice you will probably wish to use smaller values for a more subtle effect.
Sounds like you are double clicking on the .mid files and playing them back through your Media player and soundcard. Don't. Download the files and import them to tracks in your sequencer. Assign GPO instruments to the tracks (these were done with the solo strings in mind) and then play them back. This is true of all MIDI files posted for use with GPO or JABB. These aren't like audio files that can be played back directly from the link.
There was no problem getting portamento to work on KP1 for me, but using the same midi messages doesn't seem to work on KP2. i expect i'm missing something vital.
Well, I just checked a selection of random instruments in KP2 (including Vlns 1 KS) and the portamenton is working fine. Are you sure you are confining the portamento to legato only, as described in the tutorial? It only works when legato is activated.
Hi,Tom, I've not posted before, not out of haughtiness, more from awe and wonder as I gaze about the wonderful world of JABB. One point of difficulty that I still don't get: brass fall offs. They don't sound convincing yet . I'll keep working but meanwhile any helpful hints? Sid