[opus] High Sampling Rates

Benjamin Schwartz ben at bemasc.net
Fri Jun 6 23:48:57 PDT 2014

I raised the same point when I first read that article ... and I had to
read it again to understand that its conclusions are explicitly limited to
_distribution_ formats, not _intermediate editing_ formats.  No doubt, if
you start applying nonlinear functions to your audio signals, the output
may depend audibly on ultrasonic components ... but that is not the case
for Neil Young's hifi playback, or for Opus.

If you are planning on doing the kind of audio editing that involves
nonlinear transformations, then you should definitely not be using Opus as
your intermediate format anyway.  Use FLAC.

There are also some philosophical questions about whether mixing in
ultrasonics is particularly the right behavior anyway.  If I time-stretch
my audio, do I really want to hear the previously inaudible ultrasonic tone
from my compact fluorescent lightbulb ballast?  I think the answer is
"maybe", which is different from "yes".

On Fri, Jun 6, 2014 at 11:35 PM, Andrew Lentvorski <bsder at allcaps.org>

> That article is a bit too dismissive.  I agree that one cannot hear the
> difference between 48KHz/16bit and 192KHz/24bit if you just transfer the
> data directly to the audio output device.  As such, there is no good
> reason for Opus to support higher than 48KHz (especially since this is
> lossy compression, anyway).
> However, in general, that's not all you do with audio data.
> 192KHz is useful for the same reason that 24 bits is useful.  Digital
> operations often need the extra margin for many of the operations being
> carried out (IIR-type effects, mixing multiple sources, etc.)  This is
> especially true for the so-called "wet" effects that tend to mangle
> phase vs frequency (vs "dry" effects which tend to only affect amplitude
> vs frequency).
> -a
> On 6/6/14, 11:03 AM, Gregory Maxwell wrote:
> > On Sat, Feb 22, 2014 at 8:32 AM, Webdrifter <onzemeelbox at gmail.com>
> wrote:
> >> Hello,
> >> I'm an audiphile.
> >> Will opus ever be developed to work with sampling rates higher than
> 48kHz? (I hope so)
> >
> > http://people.xiph.org/~xiphmont/demo/neil-young.html
> > _______________________________________________
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> > opus at xiph.org
> > http://lists.xiph.org/mailman/listinfo/opus
> >
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