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1/*
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
7 * software.
8 *
9 * This file is part of FFmpeg.
10 *
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.
15 *
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.
20 *
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
24 */
25
26/**
27 * @file
28 * Stereo Widening Effect. Adds audio cues to move stereo image in
29 * front of the listener. Adapted from the libsox earwax effect.
30 */
31
32#include "libavutil/channel_layout.h"
33#include "avfilter.h"
34#include "audio.h"
35#include "formats.h"
36
37#define NUMTAPS 64
38
39static const int8_t filt[NUMTAPS] = {
40/* 30° 330° */
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. */
46 -5, 0,
47 9, 1,
48 6, 3, /* Input */
49 -4, -1, /* Left Right */
50 -5, -3, /* __________ __________ */
51 -2, -5, /* | | | | */
52 -7, 1, /* .---| Hh,0(f) | | Hh,0(f) |---. */
53 6, -7, /* / |__________| |__________| \ */
54 30, -29, /* / \ / \ */
55 12, -3, /* / X \ */
56 -11, 4, /* / / \ \ */
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, /* `--->| | | |<---' */
67 -4, 9, /* \_/ \_/ */
68 6, -12, /* */
69 6, -6, /* Headphones */
70 0, -11,
71 0, -5,
72 4, 0};
73
74typedef struct {
75 int16_t taps[NUMTAPS * 2];
76} EarwaxContext;
77
78static int query_formats(AVFilterContext *ctx)
79{
80 static const int sample_rates[] = { 44100, -1 };
81 int ret;
82
83 AVFilterFormats *formats = NULL;
84 AVFilterChannelLayouts *layout = NULL;
85
86 if ((ret = ff_add_format (&formats, AV_SAMPLE_FMT_S16 )) < 0 ||
87 (ret = ff_set_common_formats (ctx , formats )) < 0 ||
88 (ret = ff_add_channel_layout (&layout , AV_CH_LAYOUT_STEREO )) < 0 ||
89 (ret = ff_set_common_channel_layouts (ctx , layout )) < 0 ||
90 (ret = ff_set_common_samplerates (ctx , ff_make_format_list(sample_rates) )) < 0)
91 return ret;
92
93 return 0;
94}
95
96//FIXME: replace with DSPContext.scalarproduct_int16
97static inline int16_t *scalarproduct(const int16_t *in, const int16_t *endin, int16_t *out)
98{
99 int32_t sample;
100 int16_t j;
101
102 while (in < endin) {
103 sample = 0;
104 for (j = 0; j < NUMTAPS; j++)
105 sample += in[j] * filt[j];
106 *out = av_clip_int16(sample >> 6);
107 out++;
108 in++;
109 }
110
111 return out;
112}
113
114static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
115{
116 AVFilterLink *outlink = inlink->dst->outputs[0];
117 int16_t *taps, *endin, *in, *out;
118 AVFrame *outsamples = ff_get_audio_buffer(inlink, insamples->nb_samples);
119 int len;
120
121 if (!outsamples) {
122 av_frame_free(&insamples);
123 return AVERROR(ENOMEM);
124 }
125 av_frame_copy_props(outsamples, insamples);
126
127 taps = ((EarwaxContext *)inlink->dst->priv)->taps;
128 out = (int16_t *)outsamples->data[0];
129 in = (int16_t *)insamples ->data[0];
130
131 len = FFMIN(NUMTAPS, 2*insamples->nb_samples);
132 // copy part of new input and process with saved input
133 memcpy(taps+NUMTAPS, in, len * sizeof(*taps));
134 out = scalarproduct(taps, taps + len, out);
135
136 // process current input
137 if (2*insamples->nb_samples >= NUMTAPS ){
138 endin = in + insamples->nb_samples * 2 - NUMTAPS;
139 scalarproduct(in, endin, out);
140
141 // save part of input for next round
142 memcpy(taps, endin, NUMTAPS * sizeof(*taps));
143 } else
144 memmove(taps, taps + 2*insamples->nb_samples, NUMTAPS * sizeof(*taps));
145
146 av_frame_free(&insamples);
147 return ff_filter_frame(outlink, outsamples);
148}
149
150static const AVFilterPad earwax_inputs[] = {
151 {
152 .name = "default",
153 .type = AVMEDIA_TYPE_AUDIO,
154 .filter_frame = filter_frame,
155 },
156 { NULL }
157};
158
159static const AVFilterPad earwax_outputs[] = {
160 {
161 .name = "default",
162 .type = AVMEDIA_TYPE_AUDIO,
163 },
164 { NULL }
165};
166
167AVFilter ff_af_earwax = {
168 .name = "earwax",
169 .description = NULL_IF_CONFIG_SMALL("Widen the stereo image."),
170 .query_formats = query_formats,
171 .priv_size = sizeof(EarwaxContext),
172 .inputs = earwax_inputs,
173 .outputs = earwax_outputs,
174};
175
generated by cgit at 2024-05-17 05:01:39 (GMT)