Avoid clipping due to quantization noise to produce audible
artifacts, by detecting near-clipping signals and both attenuating
them a little and encoding escape-encoded bands (usually the
loudest) rounding towards zero instead of nearest, which tends to
decrease overall energy and thus clipping.
Currently fate tests measure numerical error so this change makes
tests using asynth (which are near clipping) report higher error
not less, because of window attenuation. Yet, they sound better,
not worse (albeit subtle, other samples aren't subtle at all).
Only measuring psychoacoustically weighted error would make for
a representative test, so that will be left for a future patch.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit adds the energy spread to the struct for each band and removes 2 unused fields.
distortion and perceptual_weight were not referenced in any file nor were they set to any value,
so it was safe to remove them. The energy spread is currently only used in the aac psy model.
It's defined as being proportional to the tonality of each band.
Reviewed-by: Claudio Freire <klaussfreire@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
The init functions marked as av_cold have to be executed in any case,
so there is no gain from trying to mark paths leading to such functions
as unlikely.
Claudio Freire
Rostislav Pehlivanov
Michael Niedermayer
Diego Biurrun
Nathan Caldwell
Mans Rullgard
Alex Converse