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IDProjectCategoryView StatusLast Update
0008403ardourbugspublic2022-11-20 01:17
Reporterunfa Assigned Tox42  
Status resolvedResolutionfixed 
Product Version6.3 
Summary0008403: Export silence trim is very hard to get working reliably
DescriptionI'm using export silence trim function in Ardour to export sounds effects for game engines.

I've always had issues with that feature, as it seems to be very pick about input signals.

Example from a job I'm doing currently:

At first trimming wouldn't work unless I disabled Ardour's export dithering - checking the exported files shown dithering noise was present and it stopped trimming from happening - solution: dither after trimming? (EDIT: I've found this to not be true in all cases - read more later).

I've disabled the dither and used NotJustAnotherDither by AirWindows instead, after a Master Limiter and before an LSP noise gate that applied 72 dB of gain reduction if signal was dropping below -60 dB (to make sure the dither noise is not going to trip up the trimming). This worked for a while, but then it stopped and I have no idea why.

Disabling the NotJustAnotherDither plug-in didn't fix it.
Also duplicating the LSP Gate 2 times for a total of 216 dB of gain reduction didn't help either.

I think silence trim needs some work - it's a very good idea, and I'd love to have this working reliably, as it's extremely helpful for working with audio for video games.

Sound effects or music loops are much easier to get working properly in a game engine with this feature, as it's much less error prone than manually aligning export markers.
Because of various issues the only real workaround is to bounce the master bus output to another track and truncate it manually there - which is laborious and error-prone.


I've checked my master bus with x42 Bit Meter plug-in - the average level was around - 400 dB, yet trim still was tripped by that.
I've added a Hard Gate plug-in set to 0.0001 threshold (the lowest possible value) and it seems to work now.

I suspect some reverb tail is producing these extremely low level sounds.

Interestingly after I've added this Hard Gate, Ardour's Shaped dither doesn't break the Trim function any more.

Could the export trim function have a customizable threshold and attack/release maybe?
I'm not sure how to get this to work reliably without using a bunch of plug-ins in the master bus and risking quality degradation (the hard gate doesn't seem like a great option, but I don't hear issues, and it fixed the trimming for me).
Tagsexport, silence trim



2022-11-20 01:16

administrator   ~0026907

Since Ardour 6.7 the default is -90 dBFS.
Silence trimming is performed before decimation on the float signal, and the given value is more than a factor of two above the max S/N of undithered 16bit audio.
Overall dithering noise (eg. Harrison's channel dithering) is also well below that level.

GIven that it is common to loudness normalize to -23 LUFS (EBU-R 128), this allows for 60dB S/N which is reasonable. Cases that require a steeper cut-off should likely use a expander/gate.


2022-11-20 01:17

administrator   ~0026908

Ardour v7 will have pushed a config-change to set the value to -90

Issue History

Date Modified Username Field Change
2020-09-13 13:31 unfa New Issue
2020-09-13 13:31 unfa Tag Attached: export
2020-09-13 13:31 unfa Tag Attached: silence trim
2022-11-20 01:16 x42 Note Added: 0026907
2022-11-20 01:17 x42 Assigned To => x42
2022-11-20 01:17 x42 Status new => resolved
2022-11-20 01:17 x42 Resolution open => fixed
2022-11-20 01:17 x42 Note Added: 0026908