  Pyramid Vector Quantizer (PVQ) is a promising technique especially for
multimedia data compression, already used in Opus audio codec and considered
for AV1 video codec. It quantizes vectors from Euclidean unit sphere by first
projecting them to $L^1$ norm unit sphere, then quantizing and encoding there.
This paper shows that the used standard radial projection is suboptimal and
proposes to tune its deformations by using parameterized power projection:
$x\to x^p/\|x^p\|$ instead, where the optimized power $p$ is applied
coordinate-wise, getting usually $\geq 0.5\, dB$ improvement comparing to
radial projection.
