• Claudio Freire's avatar
    AAC Encoder: clipping avoidance · 59216e05
    Claudio Freire authored
    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: 's avatarMichael Niedermayer <michael@niedermayer.cc>
    59216e05
aaccoder.c 57.4 KB