22 Apr
2020
22 Apr
'20
12:09 p.m.
On Tue, Apr 21, 2020 at 09:53:12AM -0700, Len Ovens wrote:
Lots of stuff out there on this. I came across an
article that proclaims:
"This worst-case example occurs when the audio tone is 1/4 of the sample
rate." That is for 48000SR a 12Khz peak. This seems unreasonable to me
though the idea that at 12Khz the peak could be as much as +3dbfs makes more
sense. It would seem to me that intersample peak posibility varies with
frequency and that the worst case would be 1/2 SR where the peak could be
infinite (in which case it would be rendered as 0). However, if everything
above 20k is filtered, that worst case is removed.
In theory there is no limit. It is possible (and quite easy) to create
a signal that produces *any* value of inter-sample peak you desire
(assuming 'perfect' D/A conversion or upsampling).
In practice (real world music signals), inter-sample peaks up to around
0.5 dB are observed.
The EBU R128 meter specs require a peak warning at -1 dB FS.
Ciao,
--
FA