Logic Pro 5.1 channel order wrong

[PluginPenguin]

I’m stuck debugging an issue with a 5.1 plugin, based on the latest JUCE 6 commit that receives surround channels in the wrong order. To verify if it’s an issue with our code or something else, I built the Surround Demo JUCE example plugin, put it on a track together with the Logic built-in meter plugin and loaded a channel placement test file on that track. The results look like that:

While the logic meter plugin shows the channels as they are played back in the test file, the juce demo plugin mixes up the channels just as we see it in our plugin. The channel indices returned by AudioChannelSet::getChannelIndexForType which we are using in our code to figure out the channel indices in the processing buffer are obviously mismatching.

I found a few topics regarding logic surround channel problems, but I got the impression that none of them reported this exact issue.

I ran the tests in Logic 10.5.1 on an Intel Mac running macOS 12.1

[daniel]

I remember having read that JUCE would reorder the channels to a consistent order.
But what happens if you change the settings of Logic here?

(Of course that wouldn’t solve the problem, just curious where the problem might come from)

[PluginPenguin]

I tried changing these settings, but that didn’t seem to make any difference.

Tbh. I’m no surround expert and never used logic for mixing something in surround, so I might be overlooking something. It seems to me as if these settings refer to channel assignments towards external hardware rather than changing the internal processing, but I might be wrong

[reuk]

I haven’t tested this right now, but I spent some time debugging and (hopefully) fixing surround sound in Logic a few months ago, so I would expect your test case to work.

Do you hav non-JUCE plugins that you can test in Logic 10.5 (I think FabFilter ProQ 3 supports surround buses, and has labelled input meters)? If other plugins are broken in the same way, this is likely to be a Logic bug, rather than a JUCE bug.

Alternatively, are you able to update to Logic 10.7.4, and see if you get different results there?

[reuk]

Just tested this out, to improve my peace of mind.

In Logic 10.7.4, I configured a channel strip with: oscillator → multichannel gain → SurroundPlugin → level meter. In 5.1 mode, the channels are ordered correctly on both the input and the output.

I think the issue you’re seeing is a bug in Logic 10.5.

[PluginPenguin]

Thank you for checking that. I‘ll try to get a Logic 10.7 version and a non juce surround plugin to investigate a bit further myself and let you know if I find out something more

[PluginPenguin]

We just had the chance to check it in Logic 10.6 and the issue is not present there. So it really seems like a Logic 10.5 bug