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IDCategoryLast Update
0008631bugs2021-03-20 18:19
ReporterShuffle777Assigned Tox42 
Status resolvedResolutionfixed 
PlatformMicrosoftOSWindowsOS Version10
Product Version6.6 
Fixed in Version 
Summary0008631: Crash on multi-channel loundness analysis
DescriptionI have several 7-channel track in a project. They work perfectly fine. But when I try to run a loudness analysis on a clip, I get a crash to desktop with the following message (see attached image) :

Exception thrown by AudioGrapher::ProcessContext <float> was not a multiple of channels: 8192 samples with \u0007 channels
Steps To ReproduceOpen a new project
Import a 7-channel audio file from disk
Right click on the new clip > [clip name] > Loudness Analysis...
Additional InformationI actually encountered the problem with my 6.5 install, so I just upgraded to 6.6 but it gives the same error.

Also, I thought channels were simply squished down to mono before calculations ; it seems from this they are not...
I don't know how multichannel LU is actually computed, but isn't it the same result as if all channels were squished down to mono (simple arithmetic average) beforehand? If that is the case, that would probably be a nice optimization to this process, wouldn't it?
Tagsanalysis, crash, loudness, multichannel



2021-03-20 14:25


LoudnessAnalysys_err.png (31,139 bytes)
LoudnessAnalysys_err.png (31,139 bytes)


2021-03-20 15:22

administrator   ~0025616

Thanks. Fixed in Ardour 6.6.149.

Note that EBU loudness analysis is not available for 7 channels, so loudness analysis will only show peak and true-peak information.


2021-03-20 18:19

reporter   ~0025617

Thank you for the fix ! That was quick! :-)

However, your answer brought me some more questions, so I made some research...

First, maybe I overlooked something but nowhere could I find any mention that this analysis is actually EBU-compatible. It seems obvious now that I know more about it, but at least mentioning it in the docs for unaware users (like I was only minutes ago) would be a good idea.

Also, as far as I know, Ardour has no care whatsoever for channel order - manual routing would defeat it anytime anyway, so this is actually a good thing. That means getting the channel order right, and thus a correct analysis, is entirely relying upon the user. That is not good practice in my (developper's) mind; at least the docs should mention the expected channel order for every supported channel count.

Issue History

Date Modified Username Field Change
2021-03-20 14:25 Shuffle777 New Issue
2021-03-20 14:25 Shuffle777 Tag Attached: analysis
2021-03-20 14:25 Shuffle777 Tag Attached: crash
2021-03-20 14:25 Shuffle777 Tag Attached: loudness
2021-03-20 14:25 Shuffle777 Tag Attached: multichannel
2021-03-20 14:25 Shuffle777 File Added: LoudnessAnalysys_err.png
2021-03-20 15:22 x42 Note Added: 0025616
2021-03-20 15:22 x42 Assigned To => x42
2021-03-20 15:22 x42 Status new => resolved
2021-03-20 15:22 x42 Resolution open => fixed
2021-03-20 18:19 Shuffle777 Note Added: 0025617