7.3 Postfilter
26.4023GPPAdditional decoder toolsEnhanced aacPlus general audio codecGeneral audio codec audio processing functionsTS
In order to compensate for a small loss in signal power for high frequencies, a first order IIR postfilter is applied to the output 
of the spline resampler, resulting in the final output 
, where 
and
The value of the parameter 
is given by Table 1.
Table 1: Postfilter coefficient 
|
|
|
|
|
8 kHz |
16 kHz |
|
|
22.05 kHz |
0.06 |
0.30 |
|
24 kHz |
0.05 |
0.24 |
Annex A (informative):
Change history
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Change history |
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Date |
TSG SA# |
TSG Doc. |
CR |
Rev |
Subject/Comment |
Old |
New |
|
2004-09 |
25 |
SP-040634 |
Approved at SA#25 |
2.0.0 |
6.0.0 |
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2005-09 |
29 |
SP-050426 |
0001 |
Correction of written specification: AAC concealment fade out factor |
6.0.0 |
6.1.0 |
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2007-06 |
36 |
Version for Release 7 |
6.1.0 |
7.0.0 |
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|
2008-12 |
42 |
Version for Release 8 |
7.0.0 |
8.0.0 |
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|
2009-12 |
46 |
Version for Release 9 |
8.0.0 |
9.0.0 |
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|
2011-03 |
51 |
Version for Release 10 |
9.0.0 |
10.0.0 |
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2012-09 |
57 |
Version for Release 11 |
10.0.0 |
11.0.0 |
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2014-09 |
65 |
Version for Release 12 |
11.0.0 |
12.0.0 |
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|
2015-12 |
70 |
Version for Release 13 |
12.0.0 |
13.0.0 |
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|
Change history |
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Date |
Meeting |
TDoc |
CR |
Rev |
Cat |
Subject/Comment |
New version |
|
2017-03 |
75 |
Version for Release 14 |
14.0.0 |
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|
2018-06 |
80 |
Version for Release 15 |
15.0.0 |
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2020-07 |
– |
– |
– |
– |
– |
Update to Rel-16 version (MCC) |
16.0.0 |
|
2022-04 |
– |
– |
– |
– |
– |
Update to Rel-17 version (MCC) |
17.0.0 |