| /* |
| * 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; |
| } |
| |
| //FIXME: replace with DSPContext.scalarproduct_int16 |
| static inline int16_t *scalarproduct(const int16_t *in, const int16_t *endin, int16_t *out) |
| { |
| int32_t sample; |
| int16_t j; |
| |
| while (in < endin) { |
| sample = 32; |
| for (j = 0; j < NUMTAPS; j++) |
| sample += in[j] * filt[j]; |
| *out = sample >> 6; |
| out++; |
| in++; |
| } |
| |
| return out; |
| } |
| |
| static void filter_samples(AVFilterLink *inlink, AVFilterBufferRef *insamples) |
| { |
| AVFilterLink *outlink = inlink->dst->outputs[0]; |
| int16_t *taps, *endin, *in, *out; |
| AVFilterBufferRef *outsamples = |
| avfilter_get_audio_buffer(inlink, AV_PERM_WRITE, |
| insamples->audio->nb_samples); |
| avfilter_copy_buffer_ref_props(outsamples, insamples); |
| |
| taps = ((EarwaxContext *)inlink->dst->priv)->taps; |
| out = (int16_t *)outsamples->data[0]; |
| in = (int16_t *)insamples ->data[0]; |
| |
| // copy part of new input and process with saved input |
| memcpy(taps+NUMTAPS, in, NUMTAPS * sizeof(*taps)); |
| out = scalarproduct(taps, taps + NUMTAPS, out); |
| |
| // process current input |
| endin = in + insamples->audio->nb_samples * 2 - NUMTAPS; |
| out = scalarproduct(in, endin, out); |
| |
| // save part of input for next round |
| memcpy(taps, endin, NUMTAPS * sizeof(*taps)); |
| |
| avfilter_filter_samples(outlink, outsamples); |
| avfilter_unref_buffer(insamples); |
| } |
| |
| AVFilter avfilter_af_earwax = { |
| .name = "earwax", |
| .description = NULL_IF_CONFIG_SMALL("Widen the stereo image."), |
| .query_formats = query_formats, |
| .priv_size = sizeof(EarwaxContext), |
| .inputs = (const AVFilterPad[]) {{ .name = "default", |
| .type = AVMEDIA_TYPE_AUDIO, |
| .filter_samples = filter_samples, |
| .config_props = config_input, |
| .min_perms = AV_PERM_READ, }, |
| { .name = NULL}}, |
| |
| .outputs = (const AVFilterPad[]) {{ .name = "default", |
| .type = AVMEDIA_TYPE_AUDIO, }, |
| { .name = NULL}}, |
| }; |