[M4IF Technotes] LFE

[Ivan Dimkovic]

Dear Vinay,
LFE channels are always of LONG type (ONLY_LONG_WINDOW in reference
code), they use SIN window shape (WS_FHG in reference decoder code) and
usually they are heavilly lowpassed with a bandwidth limitation filter.
There is no "recommended" psychoacoustic strategy, as encoder
description in the standard is purely informative - I'd say that it
would be a waste of CPU clocks to perform full psychoacoustic analysis
on a LFE channel, maybe using fixed masking threshold of [-5 to -12] dB
or something like that would work in your application.
Best regards / Mit freundlichen Grüßen
Ivan Dimkovic
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Ivan Dimkovic
MPEG-4 R&D
Ahead Software AG     phone: +49 (0)7248 911 822(direct line) 
Im Stoeckmaedle 18    fax:   +49 (0)7248 911 888 
76307 Karlsbad        email: idimkovic   nero.com
Germany               web:    www.nero.com     
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-----Original Message-----
From: technotes-admin   lists.m4if.org
[mailto:technotes-admin   lists.m4if.org] On Behalf Of Vinay K
Sent: Thursday, July 17, 2023 2:34 PM
To: technotes   lists.m4if.org
Subject: [M4IF Technotes] LFE
Dear Mpeg experts,
what should be the ideal block type for LFE channel? Is there any
standard value of masking threshold and masking enable for LFE?
In FAAC encoder, there is no processing for LFE. The standard also does
not mention anything about LFE.
Please throw some light on this matter.
With regards,
Vinay.K