MIDI Out issues

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honki-bobo
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MIDI Out issues

Post by honki-bobo » Tue Apr 21, 2020 7:23 am

Hello everyone,

maybe I'm not the only one experiencing this, but I have some issues with the MIDI Out feature of Voltage Modular.

When I open VM as a VST instrument in Cubase Pro 10.5 (Windows 10 Pro 64bit), the MIDI Out only transmits pitch, note on/off (gate), velocity and aftertouch events. Everything else is not received by a MIDI track.
But when I output the same data to a LoopMIDI device, everything gets transmitted just fine.

VM MIDI Out.jpg
VM MIDI Out.jpg (356.52 KiB) Viewed 2647 times

The left MIDI Monitor shows what's going on on the VM MIDI output, the right one shows the LoopMIDI device.

You will also notice the different time stamps (which I'm fine with, I guess) and the Aftertouch-PolyPress difference.

Since I can achieve what I need using the LoopMIDI device, this is actually not a problem for me. I just thought I'd share this if other people are experiencing similar issues.

@cherryaudio : Did I discover a bug or am I just missing something obvious here?

Best regards and stay safe,
Martin
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honki-bobo
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Re: MIDI Out issues

Post by honki-bobo » Tue Apr 21, 2020 8:31 am

While I was experimenting some more with the MIDI Out issue, I found the following:

When setting all CV TO MIDI inputs to 0 except for the gate, the resulting event is a "Note Off" on both open and closed gate on the VM MIDI output, while it is "Note On" and "Note Off" on the LoopMIDI device, as one would expect.

VM MIDI Out 2a.jpg
VM MIDI Out 2a.jpg (375.06 KiB) Viewed 2641 times

After some fidling around I found that a new "Note On" event is only generated, when the velocity input is greater than 0. The LoopMIDI device still behaves as expected.
VM MIDI Out 2b.jpg
VM MIDI Out 2b.jpg (375.21 KiB) Viewed 2641 times
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Re: MIDI Out issues

Post by honki-bobo » Tue Apr 21, 2020 10:08 am

And yet another issue:

I have created a 1 bar MIDI track with rising 16th notes at every quarter beat, sent the data to VM and used the MIDI In module to get pitch and gate data. Then I've sent the gate signal to the gate of the CV To MIDI module and the pitch signal to everything else, just to get different values for each note. I've then recorded the MIDI data from the VM MIDI output and the LoopMIDI device.

Besides the aforementioned issues with most MIDI data not getting through the VM MIDI output, I have noticed two things:
1. The timings of the "Note On" and "Note Off" events jitter massively (up to 15/120 of a 16th note at 120 BPM, that's about 16 ms or 750 samples at 48k)
2. The output of the LoopMIDI device is about 66/120 of a 16th note ahead (about 69 ms or 3300 sample at 48k)

VM MIDI Out 3.jpg
VM MIDI Out 3.jpg (449.76 KiB) Viewed 2634 times

The top editor shows the input MIDI track.
Next up is the VM patch I used.
The third window is the list editor of the track recorded from the VM MIDI output
The last editor shows the data from the track recorded on the LoopMIDI device.

I have been following the Sync with DAW - Cubase Artist 10 post on this forum and the MIDI timing issue only seems to affect Cubase. From what I have read, you (CherryAudio) seem to have fixed the sync problem on the input side of things. Can this fix be ported to the MIDI Out module maybe, so it would fix timing issues on all available MIDI devices?
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Re: MIDI Out issues

Post by honki-bobo » Fri May 01, 2020 4:18 pm

Am I the only one having these issues with MIDI output from VM?

@CherryAudio : Am I doing something wrong or missing something?
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Re: MIDI Out issues

Post by Cherry Dan » Sun May 03, 2020 7:11 pm

Hi there,

There's a lot to unpack here, but here's some information:
  • Regarding the Note Off events when there should be a Note On event, you discovered a flaw in the CV To MIDI module. See, an odd aspect of the MIDI spec is that a Note On message with a velocity of 0 is considered a Note Off message. This quirk has plagued many MIDI developers over the years. Anyway, it turns out if you plug a cable into the velocity input of the CV to MIDI module, and feed 0 volts into it, and then trigger a gate, it will send a Note On message with a velocity of 0, which is incorrect. It should be sending a velocity of 1. I've published a new version of the CV to MIDI module, so this issue should now be resolved, and you should be able to proceed with your tests.
  • Regarding various MIDI messages not getting to your host, I'd bet that you're loading the VST3 version of Voltage Modular. The VST3 design is pretty flawed when it comes to outputting MIDI to hosts, and without getting into technical details, it's likely that you wouldn't have this issue with the VST2. Is there any way you can test that?
  • Regarding MIDI timing, MIDI is an old, slow protocol, so there are efforts put into place to ensure that we do not overload it with too many messages. Conventional MIDI ports utilizing DIN cables are very slow, and vintage hardware will often freak out if you send too many MIDI messages at a time. Your DAW is probably mixing and buffering audio from the plug-in a bit ahead of playback in order to guarantee a smooth playback experience. Voltage Modular mixes audio when your DAW asks for it, and has no way to know how long it will be before you actually hear the audio, so that might explain the MIDI messages clocking in slightly early.
Let's start by testing the new CV to MIDI update, and we'll see if those main issues go away. From there, perhaps we can work on improving this further.

Thanks!
- Dan @ Cherry Audio

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Re: MIDI Out issues

Post by honki-bobo » Tue May 05, 2020 12:49 pm

Hi Dan,

I finally had the time to test the update and the VST2 version. From my tests I can report the following:
Cherry Dan wrote:
Sun May 03, 2020 7:11 pm
Regarding the Note Off events when there should be a Note On event, you discovered a flaw in the CV To MIDI module. See, an odd aspect of the MIDI spec is that a Note On message with a velocity of 0 is considered a Note Off message. This quirk has plagued many MIDI developers over the years. Anyway, it turns out if you plug a cable into the velocity input of the CV to MIDI module, and feed 0 volts into it, and then trigger a gate, it will send a Note On message with a velocity of 0, which is incorrect. It should be sending a velocity of 1. I've published a new version of the CV to MIDI module, so this issue should now be resolved, and you should be able to proceed with your tests.
I can confirm that this has been fixed. It works in the VST2 and VST3 version.

VST2 version - VM MIDI and LoopMIDI output:
VM MIDI Out 20200505 - VST2 MIDI monitor - Note On Note Off - VM MIDI and LoopMIDI.jpg
VM MIDI Out 20200505 - VST2 MIDI monitor - Note On Note Off - VM MIDI and LoopMIDI.jpg (115.96 KiB) Viewed 2384 times
VST3 version - VM MIDI and LoopMIDI output:
VM MIDI Out 20200505 - VST3 MIDI monitor - Note On Note Off - VM MIDI and LoopMIDI.jpg
VM MIDI Out 20200505 - VST3 MIDI monitor - Note On Note Off - VM MIDI and LoopMIDI.jpg (116.74 KiB) Viewed 2384 times
Cherry Dan wrote:
Sun May 03, 2020 7:11 pm
Regarding various MIDI messages not getting to your host, I'd bet that you're loading the VST3 version of Voltage Modular. The VST3 design is pretty flawed when it comes to outputting MIDI to hosts, and without getting into technical details, it's likely that you wouldn't have this issue with the VST2. Is there any way you can test that?
I can also confirm this. The VST3 version filters out (unwillingly, I assume) most MIDI messages.

VST2 version - VM MIDI and LoopMIDI output:
VM MIDI Out 20200505 - VST2 MIDI monitor - VM MIDI and LoopMIDI.jpg
VM MIDI Out 20200505 - VST2 MIDI monitor - VM MIDI and LoopMIDI.jpg (186.87 KiB) Viewed 2384 times
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honki-bobo
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Re: MIDI Out issues

Post by honki-bobo » Tue May 05, 2020 1:00 pm

VST3 version - VM MIDI and LoopMIDI output:
VM MIDI Out 20200505 - VST3 MIDI monitor - VM MIDI and LoopMIDI.jpg
VM MIDI Out 20200505 - VST3 MIDI monitor - VM MIDI and LoopMIDI.jpg (159.73 KiB) Viewed 2383 times
Cherry Dan wrote:
Sun May 03, 2020 7:11 pm
Regarding MIDI timing, MIDI is an old, slow protocol, so there are efforts put into place to ensure that we do not overload it with too many messages. Conventional MIDI ports utilizing DIN cables are very slow, and vintage hardware will often freak out if you send too many MIDI messages at a time. Your DAW is probably mixing and buffering audio from the plug-in a bit ahead of playback in order to guarantee a smooth playback experience. Voltage Modular mixes audio when your DAW asks for it, and has no way to know how long it will be before you actually hear the audio, so that might explain the MIDI messages clocking in slightly early.
I grew up in the 80s and started using MIDI in the late 80s/early 90s. I have worked with all kinds of gadgets, MIDI Thru boxes, MIDI mergers, MIDI patch bays, you name it. So, yes, I know all about the quirks of MIDI :)

Nevertheless, and for completeness sake, I have re-recorded the MIDI tracks with the VST2 and VST3 versions. Here are the results:

VST2 version:
VM MIDI Out 20200505 - VST2 - VM MIDI and LoopMIDI recorded.jpg
VM MIDI Out 20200505 - VST2 - VM MIDI and LoopMIDI recorded.jpg (244.59 KiB) Viewed 2383 times
VST3 version (VM MIDI device omits most messages):
VM MIDI Out 20200505 - VST3 - VM MIDI and LoopMIDI recorded.jpg
VM MIDI Out 20200505 - VST3 - VM MIDI and LoopMIDI recorded.jpg (190.39 KiB) Viewed 2383 times
Thanks for the update of the MIDI Out module and for your help!
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