DLLNotFound Exception on Linux: rtmidi not found

[sbrl]

Hello again, with the new getting started section, I've taken a look at this library - but I've stumbled upon a crash:

System.TypeInitializationException: The type initializer for 'Commons.Music.Midi.RtMidi.MidiDeviceManager' threw an exception. ---> System.DllNotFoundException: rtmidi
  at at (wrapper managed-to-native) Commons.Music.Midi.RtMidi.RtMidi:rtmidi_out_create_default ()
  at Commons.Music.Midi.RtMidi.RtMidiOutputDevice..ctor () [0x00000] in /svn/commons-music-prog/managed-midi/Commons.Music.Midi.Desktop/rtmidi/RtMidiSharp.cs:270
  at Commons.Music.Midi.RtMidi.MidiDeviceManager..cctor () [0x00000] in /svn/commons-music-prog/managed-midi/Commons.Music.Midi.Desktop/rtmidi/RtMidiSharp.cs:301
  --- End of inner exception stack trace ---
  at Commons.Music.Midi.RtMidi.RtMidiAccess.get_Outputs () [0x00001] in /svn/commons-music-prog/managed-midi/Commons.Music.Midi.Desktop/rtmidi/RtMidiAccess.cs:15
  at MIDITest.MainClass.Main (System.String[] args) [0x00013] in /path/to/MIDI-Test/MIDI-Test/Program.cs:13

I suspect I don't have a dependency installed. Thoughts?

[atsushieno]

Is that macOS? What is your project type? mono console app?

I'm asking, because I prepared couple of Commons.Music.Midi.dlls for Mac but they are with CoreMIDI which is from Xamarin.Mac. I suspect we'll need RtMidiSharp backend for non-XamMac apps.

[sbrl]

Nope, I'm on Linux. Here's a link to a download of the project I created: https://transfer.sh/OOEAf/MIDI-Test.7z (available for 60 days)

Here are a bunch of additional details of the system I'm doing this on:

• uname -a: Linux erreling 4.9.63-1-lts #1 SMP Sat Nov 18 17:02:19 UTC 2017 x86_64 GNU/Linux
• Monodevelop version: monodevelop-stable 7.0.1.24-2
• mono version: stable 5.0.0.100/9667aa6

[atsushieno]

Hmm, weird. I wonder if I don't understand how nuget unpacks and copies the contents for the target framework appropriately... in managed-midi-1.0.0.4.nupkg archive I put librtmidi.so (which is the shared library that you are missing) under lib/net_4_5. It seems that your .csproj does not put it along with Commons.Music.Midi.dll.

So far, could you manually add packages/Commons.Music.Midi.1.0.0.4/lib/net_4_5/librtmidi.so to your project (.csproj) with "Content" build action and "Copy If Newer" option? Or add below directly in .csproj (under some ItemGroup):

<Content Include="librtmidi.so">
  <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
</Content>

[sbrl]

Yep, copying librtmidi.so to my project and adding the MSBuild directives in an <ItemGroup/> does appear to fix the issue. As proof, here's the output of the program 😺

MIDI outputs found:
 - 1: Midi Through 14:0 (LinuxAlsa version )
 - 2: FLUID Synth (4550) 128:0 (LinuxAlsa version )

[atsushieno]

Nice :-) Let's leave this issue open until we get the right fix.

[sbrl]

Ok!

[atsushieno]

For the record, I finally implemented ALSA backend so that you wouldn't need librtmidi.so anymore since a2a98f5.

[sbrl]

Cool! I'll have to try that out and report back. It should work then pulseaudio is running, right?

(And I still need a software synthesizer running like Fluidsynth, right?)

[atsushieno]

Regardless of whether your synth backend is pulseaudio or not, our ALSA backend will connect to it as long as it is served as an ALSA MIDI device.

(And I still need a software synthesizer running like Fluidsynth, right?)

Not really ;-)

[sbrl]

Hello again! Sorry it's taken me so long to get back to you on this - I've been writing reports......

Anyway, it does appear to work correctly now without librtmidi.so - thanks! I'll have to do some further experimentation to see if I can break it lol :P

[atsushieno]

Thanks for reporting back further :-) It's still missing things like inputs, but I plan to resume working on it once I'm done with my ongoing stuff (busy until weekend of the next week).