2 * Copyright (c) 2011 Mina Nagy Zaki
3 * Copyright (c) 2000 Edward Beingessner And Sundry Contributors.
4 * This source code is freely redistributable and may be used for any purpose.
5 * This copyright notice must be maintained. Edward Beingessner And Sundry
6 * Contributors are not responsible for the consequences of using this
9 * This file is part of FFmpeg.
11 * FFmpeg is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
16 * FFmpeg is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Lesser General Public License for more details.
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with FFmpeg; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
28 * Stereo Widening Effect. Adds audio cues to move stereo image in
29 * front of the listener. Adapted from the libsox earwax effect.
32 #include "libavutil/channel_layout.h"
39 static const int8_t filt[NUMTAPS * 2] = {
41 4, -6, /* 32 tap stereo FIR filter. */
42 4, -11, /* One side filters as if the */
43 -1, -5, /* signal was from 30 degrees */
44 3, 3, /* from the ear, the other as */
45 -2, 5, /* if 330 degrees. */
49 -4, -1, /* Left Right */
50 -5, -3, /* __________ __________ */
52 -7, 1, /* .---| Hh,0(f) | | Hh,0(f) |---. */
53 6, -7, /* / |__________| |__________| \ */
54 30, -29, /* / \ / \ */
57 -3, 7, /* ____V_____ __________V V__________ _____V____ */
58 -20, 23, /* | | | | | | | | */
59 2, 0, /* | Hh,30(f) | | Hh,330(f)| | Hh,330(f)| | Hh,30(f) | */
60 1, -6, /* |__________| |__________| |__________| |__________| */
61 -14, -5, /* \ ___ / \ ___ / */
62 15, -18, /* \ / \ / _____ \ / \ / */
63 6, 7, /* `->| + |<--' / \ `-->| + |<-' */
64 15, -10, /* \___/ _/ \_ \___/ */
65 -14, 22, /* \ / \ / \ / */
66 -7, -2, /* `--->| | | |<---' */
69 6, -6, /* Headphones */
74 typedef struct EarwaxContext {
75 int16_t filter[2][NUMTAPS];
76 int16_t taps[4][NUMTAPS * 2];
81 static int query_formats(AVFilterContext *ctx)
83 static const int sample_rates[] = { 44100, -1 };
86 AVFilterFormats *formats = NULL;
87 AVFilterChannelLayouts *layout = NULL;
89 if ((ret = ff_add_format (&formats, AV_SAMPLE_FMT_S16P )) < 0 ||
90 (ret = ff_set_common_formats (ctx , formats )) < 0 ||
91 (ret = ff_add_channel_layout (&layout , AV_CH_LAYOUT_STEREO )) < 0 ||
92 (ret = ff_set_common_channel_layouts (ctx , layout )) < 0 ||
93 (ret = ff_set_common_samplerates (ctx , ff_make_format_list(sample_rates) )) < 0)
99 //FIXME: replace with DSPContext.scalarproduct_int16
100 static inline int16_t *scalarproduct(const int16_t *in, const int16_t *endin,
101 const int16_t *filt, int16_t *out)
108 for (j = 0; j < NUMTAPS; j++)
109 sample += in[j] * filt[j];
110 *out = av_clip_int16(sample >> 7);
118 static int config_input(AVFilterLink *inlink)
120 EarwaxContext *s = inlink->dst->priv;
122 for (int i = 0; i < NUMTAPS; i++) {
123 s->filter[0][i] = filt[i * 2];
124 s->filter[1][i] = filt[i * 2 + 1];
130 static void convolve(AVFilterContext *ctx, AVFrame *in,
131 int input_ch, int output_ch,
132 int filter_ch, int tap_ch)
134 EarwaxContext *s = ctx->priv;
135 int16_t *taps, *endin, *dst, *src;
138 taps = s->taps[tap_ch];
139 dst = (int16_t *)s->frame[input_ch]->data[output_ch];
140 src = (int16_t *)in->data[input_ch];
142 len = FFMIN(NUMTAPS, in->nb_samples);
143 // copy part of new input and process with saved input
144 memcpy(taps+NUMTAPS, src, len * sizeof(*taps));
145 dst = scalarproduct(taps, taps + len, s->filter[filter_ch], dst);
147 // process current input
148 if (in->nb_samples >= NUMTAPS) {
149 endin = src + in->nb_samples - NUMTAPS;
150 scalarproduct(src, endin, s->filter[filter_ch], dst);
152 // save part of input for next round
153 memcpy(taps, endin, NUMTAPS * sizeof(*taps));
155 memmove(taps, taps + in->nb_samples, NUMTAPS * sizeof(*taps));
159 static void mix(AVFilterContext *ctx, AVFrame *out,
160 int output_ch, int f0, int f1, int i0, int i1)
162 EarwaxContext *s = ctx->priv;
163 const int16_t *srcl = (const int16_t *)s->frame[f0]->data[i0];
164 const int16_t *srcr = (const int16_t *)s->frame[f1]->data[i1];
165 int16_t *dst = (int16_t *)out->data[output_ch];
167 for (int n = 0; n < out->nb_samples; n++)
168 dst[n] = av_clip_int16(srcl[n] + srcr[n]);
171 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
173 AVFilterContext *ctx = inlink->dst;
174 EarwaxContext *s = ctx->priv;
175 AVFilterLink *outlink = ctx->outputs[0];
176 AVFrame *out = ff_get_audio_buffer(outlink, in->nb_samples);
178 for (int ch = 0; ch < 2; ch++) {
179 if (!s->frame[ch] || s->frame[ch]->nb_samples < in->nb_samples) {
180 av_frame_free(&s->frame[ch]);
181 s->frame[ch] = ff_get_audio_buffer(outlink, in->nb_samples);
185 return AVERROR(ENOMEM);
192 return AVERROR(ENOMEM);
194 av_frame_copy_props(out, in);
196 convolve(ctx, in, 0, 0, 0, 0);
197 convolve(ctx, in, 0, 1, 1, 1);
198 convolve(ctx, in, 1, 0, 0, 2);
199 convolve(ctx, in, 1, 1, 1, 3);
201 mix(ctx, out, 0, 0, 1, 1, 0);
202 mix(ctx, out, 1, 0, 1, 0, 1);
205 return ff_filter_frame(outlink, out);
208 static av_cold void uninit(AVFilterContext *ctx)
210 EarwaxContext *s = ctx->priv;
212 av_frame_free(&s->frame[0]);
213 av_frame_free(&s->frame[1]);
216 static const AVFilterPad earwax_inputs[] = {
219 .type = AVMEDIA_TYPE_AUDIO,
220 .filter_frame = filter_frame,
221 .config_props = config_input,
226 static const AVFilterPad earwax_outputs[] = {
229 .type = AVMEDIA_TYPE_AUDIO,
234 AVFilter ff_af_earwax = {
236 .description = NULL_IF_CONFIG_SMALL("Widen the stereo image."),
237 .query_formats = query_formats,
238 .priv_size = sizeof(EarwaxContext),
240 .inputs = earwax_inputs,
241 .outputs = earwax_outputs,