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Relative gate threshold: -20 instead of -10(?) #92

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nofishonfriday opened this issue Oct 4, 2018 · 2 comments
Closed

Relative gate threshold: -20 instead of -10(?) #92

nofishonfriday opened this issue Oct 4, 2018 · 2 comments

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@nofishonfriday
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@nofishonfriday nofishonfriday commented Oct 4, 2018

Hi,
in https://github.com/jiixyj/libebur128/blob/master/ebur128/ebur128.c#L99 I see relative_gate set to -10.0 while in EBU Tech 3342 is specified (page 6)

The relative threshold is set to a level of −20 LU relative to the absolute-gated loudness level.

So shouldn't relative_gate be set to -20.0 also or do I misunderstand this?
Thanks.

@nofishonfriday nofishonfriday changed the title Realtive gate threshold: -20 instead of -10(?) Relative gate threshold: -20 instead of -10(?) Oct 4, 2018
@audionuma
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@audionuma audionuma commented Oct 4, 2018

Hello, as mentioned in the linked document :

The computation of Loudness Range is based on a measurement of loudness level as specified in ITU-R BS.1770 [2], albeit with a different relative gating threshold

See

stl_integrated = minus_twenty_decibels * stl_power;
where the -20 LU LRA relative gating is applied, and
minus_twenty_decibels = pow(10.0, -20.0 / 10.0);
where it is initialized.

The integrated loudness relative gate is appropriately set to -10 LU.

@nofishonfriday
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@nofishonfriday nofishonfriday commented Oct 4, 2018

Thanks for the clarification.

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