Talk:Spectral band replication

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The explanation of SBR in the second paragraph does not make sense. It says that the lower and middle portions of the audio spectrum are not touched but that the upper frequencies are encoded by transposing the lower and middle portions up into the upper frequencies. If this is true, it implies that the lower and middle frequencies are replicated, increasing their fidelity, but that the high frequencies are omitted. This makes no sense. There is also no citation for this explanation. David spector (talk) 01:05, 4 January 2010 (UTC)Reply

My understanding is that the file only has information about the mid- and low-frequency sounds, excluding the high, to reduce filesize (that the high frequencies are not encoded at all), and then when played back the decoder copies the low- and mid-frequencies up into a higher frequency, to make it sound right again (and the human brain can't tell that it's actually just copied). To me this seems a reasonable method of encoding, and would make sense with the name (i.e. band replication... instead of recording the full spectral band, record half of it, and replicate it for the other half). It could do with a cite. Maybe http://www.telos-systems.com/techtalk/aacplus/aacPlus_overview.pdf Kaldosh (talk) 10:00, 27 January 2010 (UTC)Reply

Changed to citation C xong 00:58, 8 February 2010 (UTC)Reply

Does some site have examples of sbr recordings that demonstrate how transparent different kinds of coding? — Preceding unsigned comment added by Jimw338 (talk • contribs) 02:51, 28 February 2012 (UTC)Reply

I am also interested. I'm wondering whether SBR does not actually sound better than the original. It sounds as if the processing steps in SBR could have the side effect of actually remove some harsh components of the high end, replacing it with something that is smooth and pleasant (due to being mathematically contrived from the lower order harmonics, and therefore musically related). 216.31.219.19 (talk) 20:25, 25 June 2013 (UTC)Reply