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/* |
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* Copyright (c) 2011 Mina Nagy Zaki |
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* Copyright (c) 2000 Edward Beingessner And Sundry Contributors. |
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* This source code is freely redistributable and may be used for any purpose. |
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* This copyright notice must be maintained. Edward Beingessner And Sundry |
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* Contributors are not responsible for the consequences of using this |
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* software. |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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/** |
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* @file |
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* Stereo Widening Effect. Adds audio cues to move stereo image in |
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* front of the listener. Adapted from the libsox earwax effect. |
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*/ |
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#include "libavutil/audioconvert.h" |
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#include "avfilter.h" |
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#define NUMTAPS 64 |
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static const int8_t filt[NUMTAPS] = { |
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/* 30° 330° */ |
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4, -6, /* 32 tap stereo FIR filter. */ |
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4, -11, /* One side filters as if the */ |
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-1, -5, /* signal was from 30 degrees */ |
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3, 3, /* from the ear, the other as */ |
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-2, 5, /* if 330 degrees. */ |
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-5, 0, |
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9, 1, |
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6, 3, /* Input */ |
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-4, -1, /* Left Right */ |
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-5, -3, /* __________ __________ */ |
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-2, -5, /* | | | | */ |
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-7, 1, /* .---| Hh,0(f) | | Hh,0(f) |---. */ |
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6, -7, /* / |__________| |__________| \ */ |
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30, -29, /* / \ / \ */ |
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12, -3, /* / X \ */ |
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-11, 4, /* / / \ \ */ |
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-3, 7, /* ____V_____ __________V V__________ _____V____ */ |
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-20, 23, /* | | | | | | | | */ |
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2, 0, /* | Hh,30(f) | | Hh,330(f)| | Hh,330(f)| | Hh,30(f) | */ |
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1, -6, /* |__________| |__________| |__________| |__________| */ |
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-14, -5, /* \ ___ / \ ___ / */ |
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15, -18, /* \ / \ / _____ \ / \ / */ |
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6, 7, /* `->| + |<--' / \ `-->| + |<-' */ |
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15, -10, /* \___/ _/ \_ \___/ */ |
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-14, 22, /* \ / \ / \ / */ |
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-7, -2, /* `--->| | | |<---' */ |
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-4, 9, /* \_/ \_/ */ |
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6, -12, /* */ |
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6, -6, /* Headphones */ |
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0, -11, |
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0, -5, |
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4, 0}; |
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typedef struct { |
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int16_t taps[NUMTAPS * 2]; |
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} EarwaxContext; |
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static int query_formats(AVFilterContext *ctx) |
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{ |
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AVFilterFormats *formats = NULL; |
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avfilter_add_format(&formats, AV_SAMPLE_FMT_S16); |
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avfilter_set_common_sample_formats(ctx, formats); |
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formats = NULL; |
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avfilter_add_format(&formats, AV_CH_LAYOUT_STEREO); |
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avfilter_set_common_channel_layouts(ctx, formats); |
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formats = NULL; |
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avfilter_add_format(&formats, AVFILTER_PACKED); |
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avfilter_set_common_packing_formats(ctx, formats); |
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return 0; |
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} |
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static int config_input(AVFilterLink *inlink) |
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{ |
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if (inlink->sample_rate != 44100) { |
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av_log(inlink->dst, AV_LOG_ERROR, |
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"The earwax filter only works for 44.1kHz audio. Insert " |
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"a resample filter before this\n"); |
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return AVERROR(EINVAL); |
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} |
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return 0; |
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} |
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//FIXME: replace with DSPContext.scalarproduct_int16 |
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static inline int16_t *scalarproduct(const int16_t *in, const int16_t *endin, int16_t *out) |
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{ |
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int32_t sample; |
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int16_t j; |
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while (in < endin) { |
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sample = 32; |
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for (j = 0; j < NUMTAPS; j++) |
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sample += in[j] * filt[j]; |
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*out = sample >> 6; |
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out++; |
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in++; |
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} |
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return out; |
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} |
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static void filter_samples(AVFilterLink *inlink, AVFilterBufferRef *insamples) |
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{ |
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AVFilterLink *outlink = inlink->dst->outputs[0]; |
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int16_t *taps, *endin, *in, *out; |
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AVFilterBufferRef *outsamples = |
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avfilter_get_audio_buffer(inlink, AV_PERM_WRITE, |
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insamples->audio->nb_samples); |
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taps = ((EarwaxContext *)inlink->dst->priv)->taps; |
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out = (int16_t *)outsamples->data[0]; |
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in = (int16_t *)insamples ->data[0]; |
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// copy part of new input and process with saved input |
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memcpy(taps+NUMTAPS, in, NUMTAPS * sizeof(*taps)); |
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out = scalarproduct(taps, taps + NUMTAPS, out); |
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// process current input |
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endin = in + insamples->audio->nb_samples * 2 - NUMTAPS; |
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out = scalarproduct(in, endin, out); |
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// save part of input for next round |
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memcpy(taps, endin, NUMTAPS * sizeof(*taps)); |
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avfilter_filter_samples(outlink, outsamples); |
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avfilter_unref_buffer(insamples); |
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} |
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AVFilter avfilter_af_earwax = { |
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.name = "earwax", |
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.description = NULL_IF_CONFIG_SMALL("Widen the stereo image."), |
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.query_formats = query_formats, |
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.priv_size = sizeof(EarwaxContext), |
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.inputs = (AVFilterPad[]) {{ .name = "default", |
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.type = AVMEDIA_TYPE_AUDIO, |
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.filter_samples = filter_samples, |
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.config_props = config_input, |
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.min_perms = AV_PERM_READ, }, |
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{ .name = NULL}}, |
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.outputs = (AVFilterPad[]) {{ .name = "default", |
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.type = AVMEDIA_TYPE_AUDIO, }, |
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{ .name = NULL}}, |
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}; |
Mina Nagy Zaki
Stefano Sabatini
14 years ago