[opus] [Opus][RFC][FFT][Fixed-Point][NEON] NEON-Optimize Fixed-Point FFT?
Timothy B. Terriberry
tterribe at xiph.org
Thu Dec 25 14:51:34 PST 2014
Jean-Marc Valin wrote:
> There is definitely some use for a Neon fixed-point FFT. How much
> exactly I'm not sure. Fixed-point is a bit more than just a fall-back
Well, we use fixed-point mode by default in Firefox for both Firefox OS
and Fennec (Firefox on Android). The reason is that, although there is
some NEON-class hardware where float does finally appear to be a little
bit faster (e.g., recent A9's), there are still plenty where it is
_significantly_ slower. So if you're going to pick one version to run on
many devices, fixed-point has much better worst-case performance.
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