/* * Copyright (c) 2013 Nicolas George * * 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 */ #include <float.h> #include "libavutil/avassert.h" #include "libavutil/channel_layout.h" #include "libavutil/eval.h" #include "libavutil/opt.h" #include "audio.h" #include "avfilter.h" #include "filters.h" #include "internal.h" typedef struct SineContext { const AVClass *class; double frequency; double beep_factor; char *samples_per_frame; AVExpr *samples_per_frame_expr; int sample_rate; int64_t duration; int16_t *sin; int64_t pts; uint32_t phi; ///< current phase of the sine (2pi = 1<<32) uint32_t dphi; ///< phase increment between two samples unsigned beep_period; unsigned beep_index; unsigned beep_length; uint32_t phi_beep; ///< current phase of the beep uint32_t dphi_beep; ///< phase increment of the beep } SineContext; #define CONTEXT SineContext #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM #define OPT_GENERIC(name, field, def, min, max, descr, type, deffield, ...) \ { name, descr, offsetof(CONTEXT, field), AV_OPT_TYPE_ ## type, \ { .deffield = def }, min, max, FLAGS, __VA_ARGS__ } #define OPT_INT(name, field, def, min, max, descr, ...) \ OPT_GENERIC(name, field, def, min, max, descr, INT, i64, __VA_ARGS__) #define OPT_DBL(name, field, def, min, max, descr, ...) \ OPT_GENERIC(name, field, def, min, max, descr, DOUBLE, dbl, __VA_ARGS__) #define OPT_DUR(name, field, def, min, max, descr, ...) \ OPT_GENERIC(name, field, def, min, max, descr, DURATION, str, __VA_ARGS__) #define OPT_STR(name, field, def, min, max, descr, ...) \ OPT_GENERIC(name, field, def, min, max, descr, STRING, str, __VA_ARGS__) static const AVOption sine_options[] = { OPT_DBL("frequency", frequency, 440, 0, DBL_MAX, "set the sine frequency",), OPT_DBL("f", frequency, 440, 0, DBL_MAX, "set the sine frequency",), OPT_DBL("beep_factor", beep_factor, 0, 0, DBL_MAX, "set the beep frequency factor",), OPT_DBL("b", beep_factor, 0, 0, DBL_MAX, "set the beep frequency factor",), OPT_INT("sample_rate", sample_rate, 44100, 1, INT_MAX, "set the sample rate",), OPT_INT("r", sample_rate, 44100, 1, INT_MAX, "set the sample rate",), OPT_DUR("duration", duration, 0, 0, INT64_MAX, "set the audio duration",), OPT_DUR("d", duration, 0, 0, INT64_MAX, "set the audio duration",), OPT_STR("samples_per_frame", samples_per_frame, "1024", 0, 0, "set the number of samples per frame",), {NULL} }; AVFILTER_DEFINE_CLASS(sine); #define LOG_PERIOD 15 #define AMPLITUDE 4095 #define AMPLITUDE_SHIFT 3 static void make_sin_table(int16_t *sin) { unsigned half_pi = 1 << (LOG_PERIOD - 2); unsigned ampls = AMPLITUDE << AMPLITUDE_SHIFT; uint64_t unit2 = (uint64_t)(ampls * ampls) << 32; unsigned step, i, c, s, k, new_k, n2; /* Principle: if u = exp(i*a1) and v = exp(i*a2), then exp(i*(a1+a2)/2) = (u+v) / length(u+v) */ sin[0] = 0; sin[half_pi] = ampls; for (step = half_pi; step > 1; step /= 2) { /* k = (1 << 16) * amplitude / length(u+v) In exact values, k is constant at a given step */ k = 0x10000; for (i = 0; i < half_pi / 2; i += step) { s = sin[i] + sin[i + step]; c = sin[half_pi - i] + sin[half_pi - i - step]; n2 = s * s + c * c; /* Newton's method to solve n² * k² = unit² */ while (1) { new_k = (k + unit2 / ((uint64_t)k * n2) + 1) >> 1; if (k == new_k) break; k = new_k; } sin[i + step / 2] = (k * s + 0x7FFF) >> 16; sin[half_pi - i - step / 2] = (k * c + 0x8000) >> 16; } } /* Unshift amplitude */ for (i = 0; i <= half_pi; i++) sin[i] = (sin[i] + (1 << (AMPLITUDE_SHIFT - 1))) >> AMPLITUDE_SHIFT; /* Use symmetries to fill the other three quarters */ for (i = 0; i < half_pi; i++) sin[half_pi * 2 - i] = sin[i]; for (i = 0; i < 2 * half_pi; i++) sin[i + 2 * half_pi] = -sin[i]; } static const char *const var_names[] = { "n", "pts", "t", "TB", NULL }; enum { VAR_N, VAR_PTS, VAR_T, VAR_TB, VAR_VARS_NB }; static av_cold int init(AVFilterContext *ctx) { int ret; SineContext *sine = ctx->priv; if (!(sine->sin = av_malloc(sizeof(*sine->sin) << LOG_PERIOD))) return AVERROR(ENOMEM); sine->dphi = ldexp(sine->frequency, 32) / sine->sample_rate + 0.5; make_sin_table(sine->sin); if (sine->beep_factor) { sine->beep_period = sine->sample_rate; sine->beep_length = sine->beep_period / 25; sine->dphi_beep = ldexp(sine->beep_factor * sine->frequency, 32) / sine->sample_rate + 0.5; } ret = av_expr_parse(&sine->samples_per_frame_expr, sine->samples_per_frame, var_names, NULL, NULL, NULL, NULL, 0, sine); if (ret < 0) return ret; return 0; } static av_cold void uninit(AVFilterContext *ctx) { SineContext *sine = ctx->priv; av_expr_free(sine->samples_per_frame_expr); sine->samples_per_frame_expr = NULL; av_freep(&sine->sin); } static av_cold int query_formats(AVFilterContext *ctx) { SineContext *sine = ctx->priv; static const AVChannelLayout chlayouts[] = { AV_CHANNEL_LAYOUT_MONO, { 0 } }; int sample_rates[] = { sine->sample_rate, -1 }; static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_NONE }; int ret = ff_set_common_formats_from_list(ctx, sample_fmts); if (ret < 0) return ret; ret = ff_set_common_channel_layouts_from_list(ctx, chlayouts); if (ret < 0) return ret; return ff_set_common_samplerates_from_list(ctx, sample_rates); } static av_cold int config_props(AVFilterLink *outlink) { SineContext *sine = outlink->src->priv; sine->duration = av_rescale(sine->duration, sine->sample_rate, AV_TIME_BASE); return 0; } static int activate(AVFilterContext *ctx) { AVFilterLink *outlink = ctx->outputs[0]; SineContext *sine = ctx->priv; AVFrame *frame; double values[VAR_VARS_NB] = { [VAR_N] = outlink->frame_count_in, [VAR_PTS] = sine->pts, [VAR_T] = sine->pts * av_q2d(outlink->time_base), [VAR_TB] = av_q2d(outlink->time_base), }; int i, nb_samples = lrint(av_expr_eval(sine->samples_per_frame_expr, values, sine)); int16_t *samples; if (!ff_outlink_frame_wanted(outlink)) return FFERROR_NOT_READY; if (nb_samples <= 0) { av_log(sine, AV_LOG_WARNING, "nb samples expression evaluated to %d, " "defaulting to 1024\n", nb_samples); nb_samples = 1024; } if (sine->duration) { nb_samples = FFMIN(nb_samples, sine->duration - sine->pts); av_assert1(nb_samples >= 0); if (!nb_samples) { ff_outlink_set_status(outlink, AVERROR_EOF, sine->pts); return 0; } } if (!(frame = ff_get_audio_buffer(outlink, nb_samples))) return AVERROR(ENOMEM); samples = (int16_t *)frame->data[0]; for (i = 0; i < nb_samples; i++) { samples[i] = sine->sin[sine->phi >> (32 - LOG_PERIOD)]; sine->phi += sine->dphi; if (sine->beep_index < sine->beep_length) { samples[i] += sine->sin[sine->phi_beep >> (32 - LOG_PERIOD)] * 2; sine->phi_beep += sine->dphi_beep; } if (++sine->beep_index == sine->beep_period) sine->beep_index = 0; } frame->pts = sine->pts; sine->pts += nb_samples; return ff_filter_frame(outlink, frame); } static const AVFilterPad sine_outputs[] = { { .name = "default", .type = AVMEDIA_TYPE_AUDIO, .config_props = config_props, }, }; const AVFilter ff_asrc_sine = { .name = "sine", .description = NULL_IF_CONFIG_SMALL("Generate sine wave audio signal."), .init = init, .uninit = uninit, .activate = activate, .priv_size = sizeof(SineContext), .inputs = NULL, FILTER_OUTPUTS(sine_outputs), FILTER_QUERY_FUNC(query_formats), .priv_class = &sine_class, };