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/*

 * 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 

#include "libavutil/avassert.h"

#include "libavutil/channel_layout.h"

#include "libavutil/opt.h"

#include "audio.h"

#include "avfilter.h"

#include "internal.h"

typedef struct {

    const AVClass *class;

    double frequency;

    double beep_factor;

    int samples_per_frame;

    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__)

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 fequency factor"),

    OPT_DBL("b",                 beep_factor,            0, 0, DBL_MAX,   "set the beep fequency 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_INT("samples_per_frame", samples_per_frame,   1024, 0, INT_MAX,   "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 av_cold int init(AVFilterContext *ctx)

{

    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;

    }

    return 0;

}

static av_cold void uninit(AVFilterContext *ctx)

{

    SineContext *sine = ctx->priv;

    av_freep(&sine->sin);

}

static av_cold int query_formats(AVFilterContext *ctx)

{

    SineContext *sine = ctx->priv;

    static const int64_t chlayouts[] = { AV_CH_LAYOUT_MONO, -1 };

    int sample_rates[] = { sine->sample_rate, -1 };

    static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S16,

                                                       AV_SAMPLE_FMT_NONE };

    ff_set_common_formats (ctx, ff_make_format_list(sample_fmts));

    ff_set_common_channel_layouts(ctx, avfilter_make_format64_list(chlayouts));

    ff_set_common_samplerates(ctx, ff_make_format_list(sample_rates));

    return 0;

}

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 request_frame(AVFilterLink *outlink)

{

    SineContext *sine = outlink->src->priv;

    AVFrame *frame;

    int i, nb_samples = sine->samples_per_frame;

    int16_t *samples;

    if (sine->duration) {

        nb_samples = FFMIN(nb_samples, sine->duration - sine->pts);

        av_assert1(nb_samples >= 0);

        if (!nb_samples)

            return AVERROR_EOF;

    }

    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)] << 1;

            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,

        .request_frame = request_frame,

        .config_props  = config_props,

    },

    { NULL }

};

AVFilter avfilter_asrc_sine = {

    .name          = "sine",

    .description   = NULL_IF_CONFIG_SMALL("Generate sine wave audio signal."),

    .query_formats = query_formats,

    .init          = init,

    .uninit        = uninit,

    .priv_size     = sizeof(SineContext),

    .inputs        = NULL,

    .outputs       = sine_outputs,

    .priv_class    = &sine_class,

};