/* * 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/channel_layout.h" #include "avfilter.h" #include "audio.h" #include "formats.h" #define NUMTAPS 32 static const int8_t filt[NUMTAPS * 2] = { /* 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 EarwaxContext { int16_t filter[2][NUMTAPS]; int16_t taps[4][NUMTAPS * 2]; AVFrame *frame[2]; } EarwaxContext; static int query_formats(AVFilterContext *ctx) { static const int sample_rates[] = { 44100, -1 }; int ret; AVFilterFormats *formats = NULL; AVFilterChannelLayouts *layout = NULL; if ((ret = ff_add_format (&formats, AV_SAMPLE_FMT_S16P )) < 0 || (ret = ff_set_common_formats (ctx , formats )) < 0 || (ret = ff_add_channel_layout (&layout , &(AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO)) < 0 || (ret = ff_set_common_channel_layouts (ctx , layout )) < 0 || (ret = ff_set_common_samplerates_from_list(ctx, sample_rates)) < 0) return ret; return 0; } //FIXME: replace with DSPContext.scalarproduct_int16 static inline int16_t *scalarproduct(const int16_t *in, const int16_t *endin, const int16_t *filt, int16_t *out) { int32_t sample; int16_t j; while (in < endin) { sample = 0; for (j = 0; j < NUMTAPS; j++) sample += in[j] * filt[j]; *out = av_clip_int16(sample >> 7); out++; in++; } return out; } static int config_input(AVFilterLink *inlink) { EarwaxContext *s = inlink->dst->priv; for (int i = 0; i < NUMTAPS; i++) { s->filter[0][i] = filt[i * 2]; s->filter[1][i] = filt[i * 2 + 1]; } return 0; } static void convolve(AVFilterContext *ctx, AVFrame *in, int input_ch, int output_ch, int filter_ch, int tap_ch) { EarwaxContext *s = ctx->priv; int16_t *taps, *endin, *dst, *src; int len; taps = s->taps[tap_ch]; dst = (int16_t *)s->frame[input_ch]->data[output_ch]; src = (int16_t *)in->data[input_ch]; len = FFMIN(NUMTAPS, in->nb_samples); // copy part of new input and process with saved input memcpy(taps+NUMTAPS, src, len * sizeof(*taps)); dst = scalarproduct(taps, taps + len, s->filter[filter_ch], dst); // process current input if (in->nb_samples >= NUMTAPS) { endin = src + in->nb_samples - NUMTAPS; scalarproduct(src, endin, s->filter[filter_ch], dst); // save part of input for next round memcpy(taps, endin, NUMTAPS * sizeof(*taps)); } else { memmove(taps, taps + in->nb_samples, NUMTAPS * sizeof(*taps)); } } static void mix(AVFilterContext *ctx, AVFrame *out, int output_ch, int f0, int f1, int i0, int i1) { EarwaxContext *s = ctx->priv; const int16_t *srcl = (const int16_t *)s->frame[f0]->data[i0]; const int16_t *srcr = (const int16_t *)s->frame[f1]->data[i1]; int16_t *dst = (int16_t *)out->data[output_ch]; for (int n = 0; n < out->nb_samples; n++) dst[n] = av_clip_int16(srcl[n] + srcr[n]); } static int filter_frame(AVFilterLink *inlink, AVFrame *in) { AVFilterContext *ctx = inlink->dst; EarwaxContext *s = ctx->priv; AVFilterLink *outlink = ctx->outputs[0]; AVFrame *out = ff_get_audio_buffer(outlink, in->nb_samples); for (int ch = 0; ch < 2; ch++) { if (!s->frame[ch] || s->frame[ch]->nb_samples < in->nb_samples) { av_frame_free(&s->frame[ch]); s->frame[ch] = ff_get_audio_buffer(outlink, in->nb_samples); if (!s->frame[ch]) { av_frame_free(&in); av_frame_free(&out); return AVERROR(ENOMEM); } } } if (!out) { av_frame_free(&in); return AVERROR(ENOMEM); } av_frame_copy_props(out, in); convolve(ctx, in, 0, 0, 0, 0); convolve(ctx, in, 0, 1, 1, 1); convolve(ctx, in, 1, 0, 0, 2); convolve(ctx, in, 1, 1, 1, 3); mix(ctx, out, 0, 0, 1, 1, 0); mix(ctx, out, 1, 0, 1, 0, 1); av_frame_free(&in); return ff_filter_frame(outlink, out); } static av_cold void uninit(AVFilterContext *ctx) { EarwaxContext *s = ctx->priv; av_frame_free(&s->frame[0]); av_frame_free(&s->frame[1]); } static const AVFilterPad earwax_inputs[] = { { .name = "default", .type = AVMEDIA_TYPE_AUDIO, .filter_frame = filter_frame, .config_props = config_input, }, }; static const AVFilterPad earwax_outputs[] = { { .name = "default", .type = AVMEDIA_TYPE_AUDIO, }, }; const AVFilter ff_af_earwax = { .name = "earwax", .description = NULL_IF_CONFIG_SMALL("Widen the stereo image."), .priv_size = sizeof(EarwaxContext), .uninit = uninit, FILTER_INPUTS(earwax_inputs), FILTER_OUTPUTS(earwax_outputs), FILTER_QUERY_FUNC(query_formats), };