2 * Copyright (c) 2001-2010 Krzysztof Foltman, Markus Schmidt, Thor Harald Johansen, Damien Zammit and others
4 * This file is part of FFmpeg.
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 #include "libavutil/opt.h"
28 typedef struct BiquadCoeffs {
29 double a0, a1, a2, b1, b2;
32 typedef struct BiquadD2 {
33 double a0, a1, a2, b1, b2, w1, w2;
36 typedef struct RIAACurve {
42 typedef struct AudioEmphasisContext {
45 double level_in, level_out;
48 } AudioEmphasisContext;
50 #define OFFSET(x) offsetof(AudioEmphasisContext, x)
51 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
53 static const AVOption aemphasis_options[] = {
54 { "level_in", "set input gain", OFFSET(level_in), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 64, FLAGS },
55 { "level_out", "set output gain", OFFSET(level_out), AV_OPT_TYPE_DOUBLE, {.dbl=1}, 0, 64, FLAGS },
56 { "mode", "set filter mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64=0}, 0, 1, FLAGS, "mode" },
57 { "reproduction", NULL, 0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, FLAGS, "mode" },
58 { "production", NULL, 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, FLAGS, "mode" },
59 { "type", "set filter type", OFFSET(type), AV_OPT_TYPE_INT, {.i64=4}, 0, 8, FLAGS, "type" },
60 { "col", "Columbia", 0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, FLAGS, "type" },
61 { "emi", "EMI", 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, FLAGS, "type" },
62 { "bsi", "BSI (78RPM)", 0, AV_OPT_TYPE_CONST, {.i64=2}, 0, 0, FLAGS, "type" },
63 { "riaa", "RIAA", 0, AV_OPT_TYPE_CONST, {.i64=3}, 0, 0, FLAGS, "type" },
64 { "cd", "Compact Disc (CD)", 0, AV_OPT_TYPE_CONST, {.i64=4}, 0, 0, FLAGS, "type" },
65 { "50fm", "50µs (FM)", 0, AV_OPT_TYPE_CONST, {.i64=5}, 0, 0, FLAGS, "type" },
66 { "75fm", "75µs (FM)", 0, AV_OPT_TYPE_CONST, {.i64=6}, 0, 0, FLAGS, "type" },
67 { "50kf", "50µs (FM-KF)", 0, AV_OPT_TYPE_CONST, {.i64=7}, 0, 0, FLAGS, "type" },
68 { "75kf", "75µs (FM-KF)", 0, AV_OPT_TYPE_CONST, {.i64=8}, 0, 0, FLAGS, "type" },
72 AVFILTER_DEFINE_CLASS(aemphasis);
74 static inline double biquad(BiquadD2 *bq, double in)
77 double tmp = n - bq->w1 * bq->b1 - bq->w2 * bq->b2;
78 double out = tmp * bq->a0 + bq->w1 * bq->a1 + bq->w2 * bq->a2;
86 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
88 AVFilterContext *ctx = inlink->dst;
89 AVFilterLink *outlink = ctx->outputs[0];
90 AudioEmphasisContext *s = ctx->priv;
91 const double *src = (const double *)in->data[0];
92 const double level_out = s->level_out;
93 const double level_in = s->level_in;
98 if (av_frame_is_writable(in)) {
101 out = ff_get_audio_buffer(inlink, in->nb_samples);
104 return AVERROR(ENOMEM);
106 av_frame_copy_props(out, in);
108 dst = (double *)out->data[0];
110 for (n = 0; n < in->nb_samples; n++) {
111 for (c = 0; c < inlink->channels; c++)
112 dst[c] = level_out * biquad(&s->rc[c].r1, s->rc[c].use_brickw ? biquad(&s->rc[c].brickw, src[c] * level_in) : src[c] * level_in);
113 dst += inlink->channels;
114 src += inlink->channels;
119 return ff_filter_frame(outlink, out);
122 static int query_formats(AVFilterContext *ctx)
124 AVFilterChannelLayouts *layouts;
125 AVFilterFormats *formats;
126 static const enum AVSampleFormat sample_fmts[] = {
132 layouts = ff_all_channel_counts();
134 return AVERROR(ENOMEM);
135 ret = ff_set_common_channel_layouts(ctx, layouts);
139 formats = ff_make_format_list(sample_fmts);
141 return AVERROR(ENOMEM);
142 ret = ff_set_common_formats(ctx, formats);
146 formats = ff_all_samplerates();
148 return AVERROR(ENOMEM);
149 return ff_set_common_samplerates(ctx, formats);
152 static inline void set_highshelf_rbj(BiquadD2 *bq, double freq, double q, double peak, double sr)
154 double A = sqrt(peak);
155 double w0 = freq * 2 * M_PI / sr;
156 double alpha = sin(w0) / (2 * q);
157 double cw0 = cos(w0);
158 double tmp = 2 * sqrt(A) * alpha;
159 double b0 = 0, ib0 = 0;
161 bq->a0 = A*( (A+1) + (A-1)*cw0 + tmp);
162 bq->a1 = -2*A*( (A-1) + (A+1)*cw0);
163 bq->a2 = A*( (A+1) + (A-1)*cw0 - tmp);
164 b0 = (A+1) - (A-1)*cw0 + tmp;
165 bq->b1 = 2*( (A-1) - (A+1)*cw0);
166 bq->b2 = (A+1) - (A-1)*cw0 - tmp;
176 static inline void set_lp_rbj(BiquadD2 *bq, double fc, double q, double sr, double gain)
178 double omega = 2.0 * M_PI * fc / sr;
179 double sn = sin(omega);
180 double cs = cos(omega);
181 double alpha = sn/(2 * q);
182 double inv = 1.0/(1.0 + alpha);
184 bq->a2 = bq->a0 = gain * inv * (1.0 - cs) * 0.5;
185 bq->a1 = bq->a0 + bq->a0;
186 bq->b1 = (-2.0 * cs * inv);
187 bq->b2 = ((1.0 - alpha) * inv);
190 static double freq_gain(BiquadCoeffs *c, double freq, double sr)
194 freq *= 2.0 * M_PI / sr;
198 return cabs(((double complex)c->a0 + c->a1 * z + c->a2 * z*z) /
199 ((double complex)1.0 + c->b1 * z + c->b2 * z*z));
202 static int config_input(AVFilterLink *inlink)
204 double i, j, k, g, t, a0, a1, a2, b1, b2, tau1, tau2, tau3;
205 double cutfreq, gain1kHz, gc, sr = inlink->sample_rate;
206 AVFilterContext *ctx = inlink->dst;
207 AudioEmphasisContext *s = ctx->priv;
211 s->rc = av_calloc(inlink->channels, sizeof(*s->rc));
213 return AVERROR(ENOMEM);
226 case 2: //"BSI(78rpm)"
236 i = 1. / (2. * M_PI * tau1);
237 j = 1. / (2. * M_PI * tau2);
238 k = 1. / (2. * M_PI * tau3);
240 case 4: //"CD Mastering"
243 tau3 = 0.0000001;// 1.6MHz out of audible range for null impact
244 i = 1. / (2. * M_PI * tau1);
245 j = 1. / (2. * M_PI * tau2);
246 k = 1. / (2. * M_PI * tau3);
248 case 5: //"50µs FM (Europe)"
250 tau2 = tau1 / 20;// not used
252 i = 1. / (2. * M_PI * tau1);
253 j = 1. / (2. * M_PI * tau2);
254 k = 1. / (2. * M_PI * tau3);
256 case 6: //"75µs FM (US)"
258 tau2 = tau1 / 20;// not used
260 i = 1. / (2. * M_PI * tau1);
261 j = 1. / (2. * M_PI * tau2);
262 k = 1. / (2. * M_PI * tau3);
273 if (s->type == 7 || s->type == 8) {
274 double tau = (s->type == 7 ? 0.000050 : 0.000075);
275 double f = 1.0 / (2 * M_PI * tau);
276 double nyq = sr * 0.5;
277 double gain = sqrt(1.0 + nyq * nyq / (f * f)); // gain at Nyquist
278 double cfreq = sqrt((gain - 1.0) * f * f); // frequency
282 q = pow((sr / 3269.0) + 19.5, -0.25); // somewhat poor curve-fit
284 q = pow((sr / 4750.0) + 19.5, -0.25);
286 set_highshelf_rbj(&s->rc[0].r1, cfreq, q, 1. / gain, sr);
288 set_highshelf_rbj(&s->rc[0].r1, cfreq, q, gain, sr);
289 s->rc[0].use_brickw = 0;
291 s->rc[0].use_brickw = 1;
292 if (s->mode == 0) { // Reproduction
293 g = 1. / (4.+2.*i*t+2.*k*t+i*k*t*t);
296 a2 = (-2.*t+j*t*t)*g;
297 b1 = (-8.+2.*i*k*t*t)*g;
298 b2 = (4.-2.*i*t-2.*k*t+i*k*t*t)*g;
299 } else { // Production
300 g = 1. / (2.*t+j*t*t);
301 a0 = (4.+2.*i*t+2.*k*t+i*k*t*t)*g;
302 a1 = (-8.+2.*i*k*t*t)*g;
303 a2 = (4.-2.*i*t-2.*k*t+i*k*t*t)*g;
305 b2 = (-2.*t+j*t*t)*g;
314 // the coeffs above give non-normalized value, so it should be normalized to produce 0dB at 1 kHz
316 // Note: for FM emphasis, use 100 Hz for normalization instead
317 gain1kHz = freq_gain(&coeffs, 1000.0, sr);
318 // divide one filter's x[n-m] coefficients by that value
320 s->rc[0].r1.a0 = coeffs.a0 * gc;
321 s->rc[0].r1.a1 = coeffs.a1 * gc;
322 s->rc[0].r1.a2 = coeffs.a2 * gc;
323 s->rc[0].r1.b1 = coeffs.b1;
324 s->rc[0].r1.b2 = coeffs.b2;
327 cutfreq = FFMIN(0.45 * sr, 21000.);
328 set_lp_rbj(&s->rc[0].brickw, cutfreq, 0.707, sr, 1.);
330 for (ch = 1; ch < inlink->channels; ch++) {
331 memcpy(&s->rc[ch], &s->rc[0], sizeof(RIAACurve));
337 static av_cold void uninit(AVFilterContext *ctx)
339 AudioEmphasisContext *s = ctx->priv;
343 static const AVFilterPad avfilter_af_aemphasis_inputs[] = {
346 .type = AVMEDIA_TYPE_AUDIO,
347 .config_props = config_input,
348 .filter_frame = filter_frame,
353 static const AVFilterPad avfilter_af_aemphasis_outputs[] = {
356 .type = AVMEDIA_TYPE_AUDIO,
361 AVFilter ff_af_aemphasis = {
363 .description = NULL_IF_CONFIG_SMALL("Audio emphasis."),
364 .priv_size = sizeof(AudioEmphasisContext),
365 .priv_class = &aemphasis_class,
367 .query_formats = query_formats,
368 .inputs = avfilter_af_aemphasis_inputs,
369 .outputs = avfilter_af_aemphasis_outputs,