Enable Lv2 Atom ports

[JohannesLorenz]

This commit enables atom ports and feeds them with MIDI events, if the atom ports accepts them. This enables Lv2 instruments with piano roll, e.g. the MDA Piano.

Reviewer hints:

• Please review

Tester hints:

• Wait with final testing until review is done
• Set up a wide range of packages (my current list of packages at Arch Linux is: "calf lsp-plugins mda.lv2 noise-repellent surge x42-plugins", and from the AUR: "lv2-plugins-aur-meta")
• Any Lv2 instrument is worth testing
• New effects are also available: the x42-eq and x42-dpl
• This PR is actually just about passing piano roll key presses to Lv2 instruments (which it does via MIDI internally: when you press a key in piano roll or play it in the editor, LMMS passes MIDI to the plugin, and Lv2 now recognizes these MIDI events).
• Things to check can include
  • play notes using
    • piano roll
    • keyboard keys
    • the Instrument view's keyboard
  • playing tons of notes at the same or nearly the same time

[LmmsBot]

🤖 Hey, I'm @LmmsBot from github.com/lmms/bot and I made downloads for this pull request, click me to make them magically appear! 🎩

Linux

• Linux (AppImage): lmms-1.2.3-735%2Bg5e873da-linux-x86_64.AppImage (build link)

Windows

• Windows 32-bit: lmms-1.2.3-735%2Bg5e873da14-mingw-win32.exe (build link)
• Windows 64-bit: lmms-1.2.3-735%2Bg5e873da14-mingw-win64.exe (build link)
• Windows 32-bit: lmms-1.2.2-msvc2017-win32.exe (build link)
• Windows 64-bit: lmms-1.2.2-msvc2017-win64.exe (build link)

macOS

• macOS : lmms-1.2.3-735%2Bg5e873da14-mac10.13.dmg (build link)

🤖

{"platform_name_to_artifacts": {"Linux": [{"artifact": {"title": {"title": "(AppImage)", "platform_name": "Linux"}, "link": {"link": "https://9685-15778896-gh.circle-artifacts.com/0/lmms-1.2.3-735%2Bg5e873da-linux-x86_64.AppImage"}}, "build_link": "https://circleci.com/gh/LMMS/lmms/9685?utm_campaign=vcs-integration-link&utm_medium=referral&utm_source=github-build-link"}], "Windows": [{"artifact": {"title": {"title": "32-bit", "platform_name": "Windows"}, "link": {"link": "https://9687-15778896-gh.circle-artifacts.com/0/lmms-1.2.3-735%2Bg5e873da14-mingw-win32.exe"}}, "build_link": "https://circleci.com/gh/LMMS/lmms/9687?utm_campaign=vcs-integration-link&utm_medium=referral&utm_source=github-build-link"}, {"artifact": {"title": {"title": "64-bit", "platform_name": "Windows"}, "link": {"link": "https://9688-15778896-gh.circle-artifacts.com/0/lmms-1.2.3-735%2Bg5e873da14-mingw-win64.exe"}}, "build_link": "https://circleci.com/gh/LMMS/lmms/9688?utm_campaign=vcs-integration-link&utm_medium=referral&utm_source=github-build-link"}, {"artifact": {"title": {"title": "32-bit", "platform_name": "Windows"}, "link": {"link": "https://ci.appveyor.com/api/buildjobs/rfowgksa52r9n2ch/artifacts/build/lmms-1.2.2-msvc2017-win32.exe"}}, "build_link": "https://ci.appveyor.com/project/Lukas-W/lmms/builds/35839173"}, {"artifact": {"title": {"title": "64-bit", "platform_name": "Windows"}, "link": {"link": "https://ci.appveyor.com/api/buildjobs/5nin0we8f7608fi3/artifacts/build/lmms-1.2.2-msvc2017-win64.exe"}}, "build_link": "https://ci.appveyor.com/project/Lukas-W/lmms/builds/35839173"}], "macOS": [{"artifact": {"title": {"title": "", "platform_name": "macOS"}, "link": {"link": "https://9689-15778896-gh.circle-artifacts.com/0/lmms-1.2.3-735%2Bg5e873da14-mac10.13.dmg"}}, "build_link": "https://circleci.com/gh/LMMS/lmms/9689?utm_campaign=vcs-integration-link&utm_medium=referral&utm_source=github-build-link"}]}, "commit_sha": "bec5e25132bf9d83156257ebca12751671c5e51e"}

[JohannesLorenz]

CI finally passed 😃 Ready for review.

[DomClark]

Generally looks good to me.

[JohannesLorenz]

All comments re-worked. Let's see what CI says...

[JohannesLorenz]

CI passed 🎉 @DomClark can you please check my rework?

[DomClark]

Although m_midiIn is set to the required MIDI in port if one is present, this doesn't seem to be taken into account when actually sending events to the plugin - they all go to the first visited MIDI in port instead.

[JohannesLorenz]

@DomClark I fixed it, to use m_midiIn now. Can you please re-check? The commit has a large diff, but I only refactored, nothing else.

I wonder if the MIDI to buffer code (midiInputEventToData) should be moved into a common function, so that plugins/carlabase/carla.cpp (CarlaInstrument::handleMidiEvent) can re-use the code. What do you think?

[JohannesLorenz]

@DomClark I only added 2 more commits:

1. I fixed your comment about MIDI input events that might have not been sent to m_midiIn (7ada8c0).
2. Refactoring: Carla and Lv2 share the code now which writes a MIDI event into a raw buffer (3a79181).

Can you please check those two, so we can finish the review?

[DomClark]

Everything looks correct now, as far as I can tell. I've suggested a couple of small improvements.

[IanCaio]

Not a code review (not very familiar with the Lv2 core right now), but a tester review.

Everything seems to be working fine. I tried testing other plugins besides Surge (drumkv1, ZynAddSubFX, samplv1, Black Pearl Drumkit and Red Zeppelin Drumkit) but those couldn't be loaded due to missing features. If requested I could test with another plugin known to not require those.

Surge has worked perfectly though, the Instrument Widget's, Piano Roll's and QWERTY MIDI keyboards played the notes smoothly. Tried adding lots of notes simultaneously (above 20 I guess) and it worked fine. Also tested using a hardware MIDI keyboard and it behaved properly.

No misbehavior or instabilities noticed. Very excited to see how Lv2 is growing!