[Mp4-tech][audio] High sampling rates in AAC - why?

[Dipankar Mitra]

Daniel, while it is true that most humans can hear roughly up to 20KHz (some only 15KHz), however, it is not correct to say that these sampling rates are of no use. DVD audio uses 96KHz sampling rate, and has been found to be better appreciated by audio enthusiasts than normal CD quality (although this has been debated). I guess even the super audio CD format also uses higher than 44.1KHz.
      However, irrespective of the fact whether humans can hear the difference, these higher rates are very much in use, which is why AAC supports them.
Some basic DSP web articles related to oversampling can explain why having a higher sampling rate is better when it comes to filtering, reconstruction etc.
Regards,
Dipankar
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-----Original Message-----
From: mp4-tech-bounces lists.mpegif.org [mailto:mp4-tech-bounces lists.mpegif.org]On Behalf Of D.Domazet
Sent: Tuesday, October 26, 2023 3:42 PM
To: mp4-tech lists.mpegif.org
Subject: [Mp4-tech][audio] High sampling rates in AAC - why?
Hi all,
As we know, AAC supports high sampling rates, for example 88.2kHz and 96kHz.
What is the purpose of this? If I was to test the encoder for quality at
this sampling rates, how would I do that? Is down-sampling a must since
humans can't hear this high freqs? Or AAC is used by bats and whales...
Daniel
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