[FFmpeg-devel] [PATCH] lavfi: add earwax audio filter, ported from Sox
Michael Niedermayer
michaelni at gmx.at
Tue Nov 1 03:23:51 CET 2011
On Tue, Nov 01, 2011 at 01:51:32AM +0100, Stefano Sabatini wrote:
> From: Mina Nagy Zaki <mnzaki at gmail.com>
>
> Signed-off-by: Stefano Sabatini <stefasab at gmail.com>
> ---
> doc/filters.texi | 10 +++
> libavfilter/Makefile | 1 +
> libavfilter/af_earwax.c | 159 ++++++++++++++++++++++++++++++++++++++++++++++
> libavfilter/allfilters.c | 1 +
> 4 files changed, 171 insertions(+), 0 deletions(-)
> create mode 100644 libavfilter/af_earwax.c
>
> diff --git a/doc/filters.texi b/doc/filters.texi
> index f282b18..7085ae1 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -224,6 +224,16 @@ expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3} @var{c4} @var{c5}
> @var{c6} @var{c7}]"
> @end table
>
> + at section earwax
> +
> +Make audio easier to listen to on headphones. Adds `cues' to 44.1kHz
> +stereo (i.e. audio CD format) audio so that when listened to on
> +headphones the stereo image is moved from inside your head (standard
> +for headphones) to outside and in front of the listener (standard for
> +speakers).
> +
> +Ported from SoX.
> +
> @section ladspa
>
> Apply a LADSPA effect.
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index 040d565..583dd6d 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -28,6 +28,7 @@ OBJS-$(CONFIG_AFORMAT_FILTER) += af_aformat.o
> OBJS-$(CONFIG_ANULL_FILTER) += af_anull.o
> OBJS-$(CONFIG_ARESAMPLE_FILTER) += af_aresample.o
> OBJS-$(CONFIG_ASHOWINFO_FILTER) += af_ashowinfo.o
> +OBJS-$(CONFIG_EARWAX_FILTER) += af_earwax.o
> OBJS-$(CONFIG_LADSPA_FILTER) += af_ladspa.o
> OBJS-$(CONFIG_SOX_FILTER) += af_sox.o
>
> diff --git a/libavfilter/af_earwax.c b/libavfilter/af_earwax.c
> new file mode 100644
> index 0000000..21099e2
> --- /dev/null
> +++ b/libavfilter/af_earwax.c
> @@ -0,0 +1,159 @@
> +/*
> + * Copyright (c) 2011 Mina Nagy Zaki
> + * Copyright (c) 2000 Edward Beingessner And Sundry Contributors.
> + * This source code is freely redistributable and may be used for any purpose.
> + * This copyright notice must be maintained. Edward Beingessner And Sundry
> + * Contributors are not responsible for the consequences of using this
> + * software.
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +/**
> + * @file
> + * Stereo Widening Effect. Adds audio cues to move stereo image in
> + * front of the listener. Adapted from the libsox earwax effect.
> + */
> +
> +#include "libavutil/audioconvert.h"
> +#include "avfilter.h"
> +
> +#define NUMTAPS 64
> +
> +static const int8_t filt[NUMTAPS] = {
> +/* 30° 330° */
> + 4, -6, /* 32 tap stereo FIR filter. */
> + 4, -11, /* One side filters as if the */
> + -1, -5, /* signal was from 30 degrees */
> + 3, 3, /* from the ear, the other as */
> + -2, 5, /* if 330 degrees. */
> + -5, 0,
> + 9, 1,
> + 6, 3, /* Input */
> + -4, -1, /* Left Right */
> + -5, -3, /* __________ __________ */
> + -2, -5, /* | | | | */
> + -7, 1, /* .---| Hh,0(f) | | Hh,0(f) |---. */
> + 6, -7, /* / |__________| |__________| \ */
> + 30, -29, /* / \ / \ */
> + 12, -3, /* / X \ */
> + -11, 4, /* / / \ \ */
> + -3, 7, /* ____V_____ __________V V__________ _____V____ */
> + -20, 23, /* | | | | | | | | */
> + 2, 0, /* | Hh,30(f) | | Hh,330(f)| | Hh,330(f)| | Hh,30(f) | */
> + 1, -6, /* |__________| |__________| |__________| |__________| */
> + -14, -5, /* \ ___ / \ ___ / */
> + 15, -18, /* \ / \ / _____ \ / \ / */
> + 6, 7, /* `->| + |<--' / \ `-->| + |<-' */
> + 15, -10, /* \___/ _/ \_ \___/ */
> + -14, 22, /* \ / \ / \ / */
> + -7, -2, /* `--->| | | |<---' */
> + -4, 9, /* \_/ \_/ */
> + 6, -12, /* */
> + 6, -6, /* Headphones */
> + 0, -11,
> + 0, -5,
> + 4, 0};
> +
> +typedef struct {
> + int16_t taps[NUMTAPS * 2];
> +} EarwaxContext;
> +
> +static int query_formats(AVFilterContext *ctx)
> +{
> + AVFilterFormats *formats = NULL;
> + avfilter_add_format(&formats, AV_SAMPLE_FMT_S16);
> + avfilter_set_common_sample_formats(ctx, formats);
> + formats = NULL;
> + avfilter_add_format(&formats, AV_CH_LAYOUT_STEREO);
> + avfilter_set_common_channel_layouts(ctx, formats);
> + formats = NULL;
> + avfilter_add_format(&formats, AVFILTER_PACKED);
> + avfilter_set_common_packing_formats(ctx, formats);
> +
> + return 0;
> +}
> +
> +static int config_input(AVFilterLink *inlink)
> +{
> + if (inlink->sample_rate != 44100) {
> + av_log(inlink->dst, AV_LOG_ERROR,
> + "The earwax filter only works for 44.1kHz audio. Insert "
> + "a resample filter before this\n");
> + return AVERROR(EINVAL);
> + }
> + return 0;
> +}
does the code check for stereo somewhere?
> +
> +//FIXME: replace with DSPContext.scalarproduct_int16
> +static inline int16_t *scalarproduct(int16_t *in, int16_t *endin, int16_t *out)
const in, const endin
> +{
> + int32_t sample;
> + int16_t j;
> +
> + while (in < endin) {
> + sample = 0;
32 for rounding
> + for (j = 0; j < NUMTAPS; j++)
> + sample += in[j] * filt[j];
> + *out = sample >> 6;
> + out++; in++;
> + }
i assume this matches SOX
And for the record, this can be implemented with 2 FFTs but i am not
sure it would beat a naive SIMD scalarproduct
either way, patch LGTM otherwise
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
The bravest are surely those who have the clearest vision
of what is before them, glory and danger alike, and yet
notwithstanding go out to meet it. -- Thucydides
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