On Mon, Jul 20, 2015 at 11:40:54PM -0300, Claudio Freire wrote: > On Mon, Jul 20, 2015 at 11:39 PM, Claudio Freire <klaussfre...@gmail.com> > wrote: > > On Fri, Jul 17, 2015 at 8:42 PM, Michael Niedermayer > > <mich...@niedermayer.cc> wrote: > >>> If you mean a transition in time, I don't think it makes any > >>> difference. 0.95 is a ~0.5db change in intensity, which ought to be > >>> inaudible, and windowing will already take care to make the transition > >>> smooth. And the logic wouldn't be completely free either to ramp > >>> gradually, as it would have to ramp fully to 0.95 by the time it > >>> reaches the first window marked as clipping hazard, and it could very > >>> well be the frist window. > >> > >> what i meant was that whatever condition is used to hard switch > >> between 1.0 and 0.95 could be rather a soft transition that is > >> for example > >> insteda of > >> if (x > 0.0) f = 0.95 > >> > >> something like > >> if (x > 0.0 && x<1.0) f = 1.0 + (0.95 - 1.0)*x > >> > >> so theres no discontinuity in the transition > > > > Attached is a patch with something like that. > > > > 1. It measures per-window minimum clip avoidance factor > > 2. Computes a whole-frame factor (minimum of all) > > 3. Applies the clip avoidance factor to the whole frame (to make it > > smooth and almost linear, and avoid adding harmonic distortion). > > > Sorry, that one had trailing whitespace again. > > Attached.
> libavcodec/aac.h | 4 + > libavcodec/aaccoder.c | 108 > ++++++++++++++++++++++++++++++++------------------ > libavcodec/aacenc.c | 38 +++++++++++++++++ > libavcodec/aacenc.h | 2 > libavcodec/aacpsy.c | 30 +++++++++++++ > libavcodec/psymodel.h | 1 > tests/fate/aac.mak | 4 - > 7 files changed, 145 insertions(+), 42 deletions(-) > fb3816accbd479ea10b2be6c104e28eee81ce743 > 0001-AAC-Encoder-clipping-avoidance.patch > From 57522de7c5fcdbef222c2425a4add6fa4528f0e7 Mon Sep 17 00:00:00 2001 > From: Claudio Freire <klaussfre...@gmail.com> > Date: Mon, 20 Jul 2015 22:53:24 -0300 > Subject: [PATCH] AAC Encoder: clipping avoidance applied thanks [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Rewriting code that is poorly written but fully understood is good. Rewriting code that one doesnt understand is a sign that one is less smart then the original author, trying to rewrite it will not make it better.
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