MIDI merging problems - Doepfer or Clavia issue?

Macrostructure · Joined: Sep 04, 2004 Posts: 27 G2 patch files: 3

Anyone know how MIDI mergers work?

I have my G2 MIDI data going out to a Doepfer Pocket Dial (PD) where it merges with the PD's data then on to my Firewire Audiophile. Several behaviours are seen:-

1. Move two knobs quickly on the G2. All data appears at the computer.

2. Move two knobs quickly on the PD. All data appears at the computer.

3. Move a knob on the G2 quickly and also one on the PD quickly. PD data is 95% lost.

4. Attach another PD downstream of the G2, in series with the first. Move one knob on each PD quickly. All data appears at computer.

This is the really weird one....

5. Attach PD to input of G2 as though one were going to control the G2 with it. Set up a patch to pass the PD's data through the G2 using CntlRcv and CntlSend. Move a knob on the G2 quickly and also one on the PD quickly. All the MIDI data that originates in the patch is sent correctly but maybe 95% of the data originating in the PD (now upstream!) is lost.

Anyone got any thoughts?

tim

egw · Posted: Thu Oct 14, 2004 6:50 am Post subject:

If you run a monitor program, such as Midiox, you might get a better idea of what is happening, i.e. which bytes are being received or corrupted.

blue hell · Posted: Thu Oct 14, 2004 7:39 am Post subject:

Could be that the PD doesn't handle running status correctly.

When in a MIDI stream a command is repeated there is no need to repeat the command itself as long as no other type of command needs to be sent. So multiple controller data can be sent as one command byte followed by multiple data bytes without repeating the command. The idea is that the (somewhat limitid) MIDI bandwidth can be utilized better this way.

When however a device is in a merge chain that doesn't handle running status correctly bytes can get lost or can get sent to wrong MIDI channels.

Similar problems can occur with MIDI sysex.

Maybe try a dedicated MIDI merger device instead of merging through the PD, such a device should handle this situation correctly.

Jan.

Macrostructure · Joined: Sep 04, 2004 Posts: 27 G2 patch files: 3

Hi Jan

That is true but it doesn't explain why the same error occurs if the PD is upstream or downstream of the G2....

t

Macrostructure · Joined: Sep 04, 2004 Posts: 27 G2 patch files: 3

I have been using MIDIOx extensively to diagnose this problem. 95% of the data from the PD simply does not appear at the output. Also it is not that the data from the PD is 'thinned out' - let me explain...

Merge the G2 in to the PD, for example. Turn a knob on the PD and on the G2, quickly. The data for the G2 knob appears in MIDIOx in full detail, every value is displayed 0-127. The data for the PD (maybe 1 data item in 10 of the datastream) never reaches full range - the knob has turned full range but the data values only go 1-13, say. Very weird. All the data the PD knob generated from 13 - 127 has vanished.

t

jksuperstar · Posted: Thu Oct 14, 2004 9:05 am Post subject:

What is the time stamp that midiox has for each event? If they are too close, there simply is no bandwidth for the PD to merge into. This case seems very hard for me to believe, but it's worth looking into. If you have 2 midi channels into your PC, try connecting both the MIDI merged output, and the MIDI thru output (maybe you can only do this with the G2 downstream). This might help you see when data collides, and might give some insight into how the merger is handling these things.

mosc · Posted: Thu Oct 14, 2004 10:09 am Post subject:

I use the Doepfer Pocket Control and haven't every seen this problem. It works pretty much flawlessly, unless the power supply cable falls out. Embarassed

The Pocket Dial uses rotary encoders. Maybe this has something to do with it.

blue hell · Posted: Sat Oct 16, 2004 7:03 pm Post subject: