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  1. /*
  2.  * Copyright (c) 2013 Nicolas George
  3.  *
  4.  * This file is part of FFmpeg.
  5.  *
  6.  * FFmpeg is free software; you can redistribute it and/or
  7.  * modify it under the terms of the GNU Lesser General Public License
  8.  * as published by the Free Software Foundation; either
  9.  * version 2.1 of the License, or (at your option) any later version.
  10.  *
  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
  14.  * GNU Lesser General Public License for more details.
  15.  *
  16.  * You should have received a copy of the GNU Lesser General Public License
  17.  * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
  18.  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19.  */
  20.  
  21. #include <float.h>
  22.  
  23. #include "libavutil/avassert.h"
  24. #include "libavutil/channel_layout.h"
  25. #include "libavutil/opt.h"
  26. #include "audio.h"
  27. #include "avfilter.h"
  28. #include "internal.h"
  29.  
  30. typedef struct {
  31.     const AVClass *class;
  32.     double frequency;
  33.     double beep_factor;
  34.     int samples_per_frame;
  35.     int sample_rate;
  36.     int64_t duration;
  37.     int16_t *sin;
  38.     int64_t pts;
  39.     uint32_t phi;  ///< current phase of the sine (2pi = 1<<32)
  40.     uint32_t dphi; ///< phase increment between two samples
  41.     unsigned beep_period;
  42.     unsigned beep_index;
  43.     unsigned beep_length;
  44.     uint32_t phi_beep;  ///< current phase of the beep
  45.     uint32_t dphi_beep; ///< phase increment of the beep
  46. } SineContext;
  47.  
  48. #define CONTEXT SineContext
  49. #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
  50.  
  51. #define OPT_GENERIC(name, field, def, min, max, descr, type, deffield, ...) \
  52.     { name, descr, offsetof(CONTEXT, field), AV_OPT_TYPE_ ## type,          \
  53.       { .deffield = def }, min, max, FLAGS, __VA_ARGS__ }
  54.  
  55. #define OPT_INT(name, field, def, min, max, descr, ...) \
  56.     OPT_GENERIC(name, field, def, min, max, descr, INT, i64, __VA_ARGS__)
  57.  
  58. #define OPT_DBL(name, field, def, min, max, descr, ...) \
  59.     OPT_GENERIC(name, field, def, min, max, descr, DOUBLE, dbl, __VA_ARGS__)
  60.  
  61. #define OPT_DUR(name, field, def, min, max, descr, ...) \
  62.     OPT_GENERIC(name, field, def, min, max, descr, DURATION, str, __VA_ARGS__)
  63.  
  64. static const AVOption sine_options[] = {
  65.     OPT_DBL("frequency",         frequency,            440, 0, DBL_MAX,   "set the sine frequency"),
  66.     OPT_DBL("f",                 frequency,            440, 0, DBL_MAX,   "set the sine frequency"),
  67.     OPT_DBL("beep_factor",       beep_factor,            0, 0, DBL_MAX,   "set the beep fequency factor"),
  68.     OPT_DBL("b",                 beep_factor,            0, 0, DBL_MAX,   "set the beep fequency factor"),
  69.     OPT_INT("sample_rate",       sample_rate,        44100, 1, INT_MAX,   "set the sample rate"),
  70.     OPT_INT("r",                 sample_rate,        44100, 1, INT_MAX,   "set the sample rate"),
  71.     OPT_DUR("duration",          duration,               0, 0, INT64_MAX, "set the audio duration"),
  72.     OPT_DUR("d",                 duration,               0, 0, INT64_MAX, "set the audio duration"),
  73.     OPT_INT("samples_per_frame", samples_per_frame,   1024, 0, INT_MAX,   "set the number of samples per frame"),
  74.     {NULL}
  75. };
  76.  
  77. AVFILTER_DEFINE_CLASS(sine);
  78.  
  79. #define LOG_PERIOD 15
  80. #define AMPLITUDE 4095
  81. #define AMPLITUDE_SHIFT 3
  82.  
  83. static void make_sin_table(int16_t *sin)
  84. {
  85.     unsigned half_pi = 1 << (LOG_PERIOD - 2);
  86.     unsigned ampls = AMPLITUDE << AMPLITUDE_SHIFT;
  87.     uint64_t unit2 = (uint64_t)(ampls * ampls) << 32;
  88.     unsigned step, i, c, s, k, new_k, n2;
  89.  
  90.     /* Principle: if u = exp(i*a1) and v = exp(i*a2), then
  91.        exp(i*(a1+a2)/2) = (u+v) / length(u+v) */
  92.     sin[0] = 0;
  93.     sin[half_pi] = ampls;
  94.     for (step = half_pi; step > 1; step /= 2) {
  95.         /* k = (1 << 16) * amplitude / length(u+v)
  96.            In exact values, k is constant at a given step */
  97.         k = 0x10000;
  98.         for (i = 0; i < half_pi / 2; i += step) {
  99.             s = sin[i] + sin[i + step];
  100.             c = sin[half_pi - i] + sin[half_pi - i - step];
  101.             n2 = s * s + c * c;
  102.             /* Newton's method to solve n² * k² = unit² */
  103.             while (1) {
  104.                 new_k = (k + unit2 / ((uint64_t)k * n2) + 1) >> 1;
  105.                 if (k == new_k)
  106.                     break;
  107.                 k = new_k;
  108.             }
  109.             sin[i + step / 2] = (k * s + 0x7FFF) >> 16;
  110.             sin[half_pi - i - step / 2] = (k * c + 0x8000) >> 16;
  111.         }
  112.     }
  113.     /* Unshift amplitude */
  114.     for (i = 0; i <= half_pi; i++)
  115.         sin[i] = (sin[i] + (1 << (AMPLITUDE_SHIFT - 1))) >> AMPLITUDE_SHIFT;
  116.     /* Use symmetries to fill the other three quarters */
  117.     for (i = 0; i < half_pi; i++)
  118.         sin[half_pi * 2 - i] = sin[i];
  119.     for (i = 0; i < 2 * half_pi; i++)
  120.         sin[i + 2 * half_pi] = -sin[i];
  121. }
  122.  
  123. static av_cold int init(AVFilterContext *ctx)
  124. {
  125.     SineContext *sine = ctx->priv;
  126.  
  127.     if (!(sine->sin = av_malloc(sizeof(*sine->sin) << LOG_PERIOD)))
  128.         return AVERROR(ENOMEM);
  129.     sine->dphi = ldexp(sine->frequency, 32) / sine->sample_rate + 0.5;
  130.     make_sin_table(sine->sin);
  131.  
  132.     if (sine->beep_factor) {
  133.         sine->beep_period = sine->sample_rate;
  134.         sine->beep_length = sine->beep_period / 25;
  135.         sine->dphi_beep = ldexp(sine->beep_factor * sine->frequency, 32) /
  136.                           sine->sample_rate + 0.5;
  137.     }
  138.  
  139.     return 0;
  140. }
  141.  
  142. static av_cold void uninit(AVFilterContext *ctx)
  143. {
  144.     SineContext *sine = ctx->priv;
  145.  
  146.     av_freep(&sine->sin);
  147. }
  148.  
  149. static av_cold int query_formats(AVFilterContext *ctx)
  150. {
  151.     SineContext *sine = ctx->priv;
  152.     static const int64_t chlayouts[] = { AV_CH_LAYOUT_MONO, -1 };
  153.     int sample_rates[] = { sine->sample_rate, -1 };
  154.     static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16,
  155.                                                        AV_SAMPLE_FMT_NONE };
  156.  
  157.     ff_set_common_formats (ctx, ff_make_format_list(sample_fmts));
  158.     ff_set_common_channel_layouts(ctx, avfilter_make_format64_list(chlayouts));
  159.     ff_set_common_samplerates(ctx, ff_make_format_list(sample_rates));
  160.     return 0;
  161. }
  162.  
  163. static av_cold int config_props(AVFilterLink *outlink)
  164. {
  165.     SineContext *sine = outlink->src->priv;
  166.     sine->duration = av_rescale(sine->duration, sine->sample_rate, AV_TIME_BASE);
  167.     return 0;
  168. }
  169.  
  170. static int request_frame(AVFilterLink *outlink)
  171. {
  172.     SineContext *sine = outlink->src->priv;
  173.     AVFrame *frame;
  174.     int i, nb_samples = sine->samples_per_frame;
  175.     int16_t *samples;
  176.  
  177.     if (sine->duration) {
  178.         nb_samples = FFMIN(nb_samples, sine->duration - sine->pts);
  179.         av_assert1(nb_samples >= 0);
  180.         if (!nb_samples)
  181.             return AVERROR_EOF;
  182.     }
  183.     if (!(frame = ff_get_audio_buffer(outlink, nb_samples)))
  184.         return AVERROR(ENOMEM);
  185.     samples = (int16_t *)frame->data[0];
  186.  
  187.     for (i = 0; i < nb_samples; i++) {
  188.         samples[i] = sine->sin[sine->phi >> (32 - LOG_PERIOD)];
  189.         sine->phi += sine->dphi;
  190.         if (sine->beep_index < sine->beep_length) {
  191.             samples[i] += sine->sin[sine->phi_beep >> (32 - LOG_PERIOD)] << 1;
  192.             sine->phi_beep += sine->dphi_beep;
  193.         }
  194.         if (++sine->beep_index == sine->beep_period)
  195.             sine->beep_index = 0;
  196.     }
  197.  
  198.     frame->pts = sine->pts;
  199.     sine->pts += nb_samples;
  200.     return ff_filter_frame(outlink, frame);
  201. }
  202.  
  203. static const AVFilterPad sine_outputs[] = {
  204.     {
  205.         .name          = "default",
  206.         .type          = AVMEDIA_TYPE_AUDIO,
  207.         .request_frame = request_frame,
  208.         .config_props  = config_props,
  209.     },
  210.     { NULL }
  211. };
  212.  
  213. AVFilter avfilter_asrc_sine = {
  214.     .name          = "sine",
  215.     .description   = NULL_IF_CONFIG_SMALL("Generate sine wave audio signal."),
  216.     .query_formats = query_formats,
  217.     .init          = init,
  218.     .uninit        = uninit,
  219.     .priv_size     = sizeof(SineContext),
  220.     .inputs        = NULL,
  221.     .outputs       = sine_outputs,
  222.     .priv_class    = &sine_class,
  223. };
  224.