# Crash when converting MIDI 1 to MIDI 2

**URL:** <https://forum.juce.com/t/crash-when-converting-midi-1-to-midi-2/56644>\
**Category:** General JUCE discussion\
**Created:** [June 14, 2023, 7:19am UTC](https://forum.juce.com/t/crash-when-converting-midi-1-to-midi-2/56644 "2023-06-14T07:19:51Z")\
**Posts on this page:** 12\
**Page:** 1

<div class="post-metadata">

**Author:** ![leehu](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/leehu/32/3280_2.png) [@leehu](https://forum.juce.com/u/leehu)\
**Post date:** [June 14, 2023, 7:19am UTC](https://forum.juce.com/t/crash-when-converting-midi-1-to-midi-2/56644/1 "2023-06-14T07:19:51Z")

</div>

Hi, looks like I’ve had a crash when doing the conversion:

```plaintext
0 AudioToolboxCore 0x189657b84 caulk::inplace_function_detail::vtable<void, MIDI::EventList const*>::vtable<APMIDIRouter::handleSetProperty(void*, AudioUnitPluginDispatch const&, unsigned int, unsigned int, unsigned int, void const*, unsigned int)::$_17::operator()(void*, AudioTimeStamp const*, unsigned int, MIDIPacketList const*) const::'lambda'(MIDIPacket const*)::operator()(MIDIPacket const*) const::'lambda'(MIDI::EventList const*)>(caulk::inplace_function_detail::wrapper<APMIDIRouter::handleSetProperty(void*, AudioUnitPluginDispatch const&, unsigned int, unsigned int, unsigned int, void const*, unsigned int)::$_17::operator()(void*, AudioTimeStamp const*, unsigned int, MIDIPacketList const*) const::'lambda'(MIDIPacket const*)::operator()(MIDIPacket const*) const::'lambda'(MIDI::EventList const*)>)::'lambda'(void*, MIDI::EventList const*&&)::__invoke(void*, MIDI::EventList const*&&) + 60
1 AudioToolboxCore 0x189581a1c MIDI::LegacyMIDIConverter<MIDI::MIDI_1_to_2_Translator>::convertLegacyDataToEventList(std::__1::span<unsigned char const, 18446744073709551615ul>, unsigned long long, caulk::inplace_function<void (MIDI::EventList const*), 48ul, 8ul>) + 224
2 AudioToolboxCore 0x189657a90 APMIDIRouter::handleSetProperty(void*, AudioUnitPluginDispatch const&, unsigned int, unsigned int, unsigned int, void const*, unsigned int)::$_17::__invoke(void*, AudioTimeStamp const*, unsigned int, MIDIPacketList const*) + 156
3 Melody Sauce 2 0x14b3f4780 JuceAU::Render(unsigned int&, AudioTimeStamp const&, unsigned int) + 4296
4 Melody Sauce 2 0x14b405994 ausdk::AUMethodRender(void*, unsigned int*, AudioTimeStamp const*, unsigned int, unsigned int, AudioBufferList*) + 1508
5 AudioToolboxCore 0x18967147c AudioUnitRender + 420
6 AudioToolboxCore 0x1895ec3b8 invocation function for block in AUAudioUnitV2Bridge_Renderer::renderBlock() + 628
7 AudioToolboxCore 0x1896048d0 void* caulk::thread_proxy<std::__1::tuple<caulk::thread::attributes, AUOOPRenderingServer::AUOOPRenderingServer(int, int, int, std::__1::vector<AudioStreamBasicDescription, std:: __1::allocator<AudioStreamBasicDescription>> const&, unsigned int, unsigned int, applesauce::xpc::dict const&, std::__ 1::shared_ptr<auoop::WorkgroupMirror>)::$_0, std::__1::tuple<>>>(void*) + 2304

```

Anything I can do to help track this down? Has happened once or twice to a couple of customers, so not a consistent isse.

thx

---

<div class="post-metadata">

**Author:** ![reuk](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/reuk/32/21494_2.png) [@reuk](https://forum.juce.com/u/reuk)\
**Post date:** [June 14, 2023, 10:16am UTC](https://forum.juce.com/t/crash-when-converting-midi-1-to-midi-2/56644/2 "2023-06-14T10:16:40Z")

</div>

That looks like it’s crashing inside system code, rather than in JUCE. I think we’d need to know the following:

- What OS and platform does this happen on? If it’s only on older macOS versions, perhaps it’s already been fixed.
- What deployment target are you using, and what Xcode version are you using to build released plugins?
- What’s the sequence of MIDI events that causes the crash?

---

<div class="post-metadata">

**Author:** ![leehu](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/leehu/32/3280_2.png) [@leehu](https://forum.juce.com/u/leehu)\
**Post date:** [June 14, 2023, 11:19am UTC](https://forum.juce.com/t/crash-when-converting-midi-1-to-midi-2/56644/3 "2023-06-14T11:19:08Z")

</div>

Hi,  
MacOS Ventura 13.4  
XCode probably would have been 14.2.x

This is when restoring a project so it’s at plugin load time so not sure what MIDI is going through the system at that point. Trying to get a copy of the project to see if it triggers the issue as not able to reproduce myself.

thx

---

<div class="post-metadata">

**Author:** ![haydenbursk](https://avatars.discourse-cdn.com/v4/letter/h/dec6dc/32.png) [@haydenbursk](https://forum.juce.com/u/haydenbursk)\
**Post date:** [June 22, 2023, 3:53pm UTC](https://forum.juce.com/t/crash-when-converting-midi-1-to-midi-2/56644/4 "2023-06-22T15:53:25Z")

</div>

I’m tracking the same issue on this thread with a repro.

> [@Logic 10.7.8 and native M1 crash on some systems](https://forum.juce.com/t/logic-10-7-8-and-native-m1-crash-on-some-systems-solved/56495/12):
>
> Yes. That’s the exact point of the EXC\_BAD\_ACCESS. Reproducible with the combo of Logic Pro 10.7.8 with MIDI 2.0 enabled and an Apple Silicon Mac running native without Rosetta. And it occurs in the first process callback on plugin instantiation.

---

<div class="post-metadata">

**Author:** ![reuk](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/reuk/32/21494_2.png) [@reuk](https://forum.juce.com/u/reuk)\
**Post date:** [June 22, 2023, 8:14pm UTC](https://forum.juce.com/t/crash-when-converting-midi-1-to-midi-2/56644/5 "2023-06-22T20:14:12Z")

</div>

I’m able to reproduce this issue with the AudioPluginDemo AUv2 built from develop, in Logic 10.7.8 with MIDI 2.0 enabled:

```auto
0 AudioToolboxCore 0x18b57fb84 caulk::inplace_function_detail::vtable<void, MIDI::EventList const*>::vtable<APMIDIRouter::handleSetProperty(void*, AudioUnitPluginDispatch const&, unsigned int, unsigned int, unsigned int, void const*, unsigned int)::$_17::operator()(void*, AudioTimeStamp const*, unsigned int, MIDIPacketList const*) const::'lambda'(MIDIPacket const*)::operator()(MIDIPacket const*) const::'lambda'(MIDI::EventList const*)>(caulk::inplace_function_detail::wrapper<APMIDIRouter::handleSetProperty(void*, AudioUnitPluginDispatch const&, unsigned int, unsigned int, unsigned int, void const*, unsigned int)::$_17::operator()(void*, AudioTimeStamp const*, unsigned int, MIDIPacketList const*) const::'lambda'(MIDIPacket const*)::operator()(MIDIPacket const*) const::'lambda'(MIDI::EventList const*)>)::'lambda'(void*, MIDI::EventList const*&&)::__invoke(void*, MIDI::EventList const*&&) + 60
1 AudioToolboxCore 0x18b4a9a1c MIDI::LegacyMIDIConverter<MIDI::MIDI_1_to_2_Translator>::convertLegacyDataToEventList(std::__1::span<unsigned char const, 18446744073709551615ul>, unsigned long long, caulk::inplace_function<void (MIDI::EventList const*), 48ul, 8ul>) + 224
2 AudioToolboxCore 0x18b57fa90 APMIDIRouter::handleSetProperty(void*, AudioUnitPluginDispatch const&, unsigned int, unsigned int, unsigned int, void const*, unsigned int)::$_17::__invoke(void*, AudioTimeStamp const*, unsigned int, MIDIPacketList const*) + 156
3 AudioPluginDemo 0x10d835f00 JuceAU::pushMidiOutput(unsigned int)::'lambda2'()::operator()() const + 80 (juce_audio_plugin_client_AU_1.mm:2152)
4 AudioPluginDemo 0x10d8312a8 JuceAU::pushMidiOutput(unsigned int) + 848 (juce_audio_plugin_client_AU_1.mm:2190)

```

The last line in JUCE code is the body of this lambda. `midiCallback` is a struct provided by the host.

```auto
const auto send = [&]
{
    midiCallback.midiOutputCallback (midiCallback.userData, &lastTimeStamp, 0, packetList);
};

```

I haven’t dug into this enough to know whether there’s something we can do in JUCE to avoid the crash. I do find it surprising that this code path is even taken - JUCE AUs support the newer MIDIEventList API, and we should only end up calling the line above if the host provides a PacketList callback (old) but not an EventList callback (new).

In fact, when running natively, it looks like Logic _does_ try to supply an EventList callback, but the block it passes is nil, so JUCE doesn’t call it. If I instead run Logic in Rosetta mode, then it doesn’t even try to set the callback.

There definitely seems to be some kind of bug on Apple’s side here. I would expect that the midi callback shouldn’t crash, regardless of the inputs that are passed. The difference in behaviour between the Rosetta/Native versions is also sligtly unexpected.

I’ll try filing a bug report and post here if I hear anything. The Feedback Assistant ID is FB12420223.

Also pinging @mfritze in case this is already a known issue.

---

<div class="post-metadata">

**Author:** ![mfritze](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/mfritze/32/9008_2.png) [@mfritze](https://forum.juce.com/u/mfritze)\
**Post date:** [June 22, 2023, 8:34pm UTC](https://forum.juce.com/t/crash-when-converting-midi-1-to-midi-2/56644/6 "2023-06-22T20:34:16Z")

</div>

Seems Logic is not involved in that crash? What does the line juce\_audio\_plugin\_client\_AU\_1.mm:1964 do?

Thread 3 Crashed:: Dispatch queue: com.apple.NSXPCConnection.user.anonymous.84864  
0 libobjc.A.dylib 0x189391c20 objc\_msgSend + 32  
1 AudioPluginDemo 0x10f697ec8 JuceAU::ScopedMIDIEventListBlock::ScopedMIDIEventListBlock(int (long long, unsigned char, MIDIEventList const\*) block\_pointer) + 40 (juce\_audio\_plugin\_client\_AU\_1.mm:1964)  
2 AudioPluginDemo 0x10f697e90 JuceAU::ScopedMIDIEventListBlock::ScopedMIDIEventListBlock(int (long long, unsigned char, MIDIEventList const\*) block\_pointer) + 36 (juce\_audio\_plugin\_client\_AU\_1.mm:1964)  
3 AudioPluginDemo 0x10f697d48 JuceAU::ScopedMIDIEventListBlock::copy(int (long long, unsigned char, MIDIEventList const\*) block\_pointer) + 44 (juce\_audio\_plugin\_client\_AU\_1.mm:1947)  
4 AudioPluginDemo 0x10f66b4b4 JuceAU::SetProperty(unsigned int, unsigned int, unsigned int, void const\*, unsigned int) + 256 (juce\_audio\_plugin\_client\_AU\_1.mm:668)  
5 AudioPluginDemo 0x10f6b2a94 ausdk::AUBase::DispatchSetProperty(unsigned int, unsigned int, unsigned int, void const\*, unsigned int) + 2844 (AUBase.cpp:846)  
6 AudioPluginDemo 0x10f6bd65c ausdk::AUMethodSetProperty(void\*, unsigned int, unsigned int, unsigned int, void const\*, unsigned int) + 128 (AUPlugInDispatch.cpp:182)  
7 AudioToolboxCore 0x18b59851c AudioUnitSetProperty + 1008  
8 AudioToolboxCore 0x18b513eac -[AUAudioUnitV2Bridge setMIDIOutputEventBlock:] + 152  
9 AudioToolboxCore 0x18b3e61e4 -[AURemoteHost initialize:reply:] + 848

---

<div class="post-metadata">

**Author:** ![reuk](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/reuk/32/21494_2.png) [@reuk](https://forum.juce.com/u/reuk)\
**Post date:** [June 22, 2023, 9:31pm UTC](https://forum.juce.com/t/crash-when-converting-midi-1-to-midi-2/56644/7 "2023-06-22T21:31:50Z")

</div>

Sorry about that, I accidentally attached the wrong crash log. I’ve updated the FB issue with a new crash log.

---

<div class="post-metadata">

**Author:** ![mfritze](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/mfritze/32/9008_2.png) [@mfritze](https://forum.juce.com/u/mfritze)\
**Post date:** [June 22, 2023, 10:22pm UTC](https://forum.juce.com/t/crash-when-converting-midi-1-to-midi-2/56644/8 "2023-06-22T22:22:01Z")

</div>

Looked at the new one. My first guess is that it is an issue between your code and macOS – not Logic. Can be Logic, but not my first guess. Looks like a MIDI conversion from MIDI-1 to MIDI-2 is called and the lambda function to be called – and it crashes there. Is it possible that your lambda function is deallocated at that point and it jumps into nowhere?

---

<div class="post-metadata">

**Author:** ![haydenbursk](https://avatars.discourse-cdn.com/v4/letter/h/dec6dc/32.png) [@haydenbursk](https://forum.juce.com/u/haydenbursk)\
**Post date:** [June 22, 2023, 10:23pm UTC](https://forum.juce.com/t/crash-when-converting-midi-1-to-midi-2/56644/9 "2023-06-22T22:23:44Z")

</div>

I can confirm there is no crash with Logic 10.7.4, Apple Silicon, and MIDI 2.0 enabled. I’m not able to test any other versions between 10.7.4 and 10.7.8 as they are difficult to obtain.

---

<div class="post-metadata">

**Author:** ![haydenbursk](https://avatars.discourse-cdn.com/v4/letter/h/dec6dc/32.png) [@haydenbursk](https://forum.juce.com/u/haydenbursk)\
**Post date:** [June 22, 2023, 10:56pm UTC](https://forum.juce.com/t/crash-when-converting-midi-1-to-midi-2/56644/10 "2023-06-22T22:56:22Z")

</div>

I have to confirm, but if our plugin doesn’t produce MIDI output, setting `JucePlugin_ProducesMidiOutput` to 0, avoids that bit of code that’s crashing in `pushMidiOutput` and avoids the crash. If again of course, you don’t need MIDI output.

---

<div class="post-metadata">

**Author:** ![reuk](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/reuk/32/21494_2.png) [@reuk](https://forum.juce.com/u/reuk)\
**Post date:** [June 27, 2023, 10:37am UTC](https://forum.juce.com/t/crash-when-converting-midi-1-to-midi-2/56644/11 "2023-06-27T10:37:57Z")

</div>

> [@mfritze](#):
>
> Is it possible that your lambda function is deallocated at that point and it jumps into nowhere?

The lambda in question is in a system framework, not provided by JUCE. If the lambda is getting deallocated, there’s not much we can do about it in JUCE. As far as I can tell, JUCE only calls the host-provided MIDI output callback at points where it is valid to do so.

Based on the response here, it sounds like this is confirmed as a bug in CoreAudio (linking here to keep both threads in sync).

> [@Logic 10.7.8 and native M1 crash on some systems](https://forum.juce.com/t/logic-10-7-8-and-native-m1-crash-on-some-systems/56495/16):
>
> AUv2 instruments, which use legacy MIDI 1.0 and implement a MIDI Output Callback crash CoreAudio inside the MIDI 2.0 translation. So, yes, disabling MIDI 2 should solve it right now. That said, we also found a solution on the Logic Pro side to avoid that crash altogether. But we need to continue to look into this further.

---

<div class="post-metadata">

**Author:** ![eyalamir](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/eyalamir/32/2978_2.png) [@eyalamir](https://forum.juce.com/u/eyalamir)\
**Post date:** [July 5, 2023, 8:45pm UTC](https://forum.juce.com/t/crash-when-converting-midi-1-to-midi-2/56644/12 "2023-07-05T20:45:20Z")

</div>

@mfritze We ran into this crash as well, and talking to a few other plugin vendors that aren’t using JUCE - they seem to be running into the same crash.