| 
							- /*
 -  * Copyright (c) 2013-2015 Paul B Mahol
 -  *
 -  * 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
 -  */
 - 
 - /**
 -  * @file
 -  * fade audio filter
 -  */
 - 
 - #include "libavutil/opt.h"
 - #include "audio.h"
 - #include "avfilter.h"
 - #include "filters.h"
 - #include "internal.h"
 - 
 - typedef struct AudioFadeContext {
 -     const AVClass *class;
 -     int type;
 -     int curve, curve2;
 -     int64_t nb_samples;
 -     int64_t start_sample;
 -     int64_t duration;
 -     int64_t start_time;
 -     int overlap;
 -     int cf0_eof;
 -     int crossfade_is_over;
 -     int64_t pts;
 - 
 -     void (*fade_samples)(uint8_t **dst, uint8_t * const *src,
 -                          int nb_samples, int channels, int direction,
 -                          int64_t start, int64_t range, int curve);
 -     void (*crossfade_samples)(uint8_t **dst, uint8_t * const *cf0,
 -                               uint8_t * const *cf1,
 -                               int nb_samples, int channels,
 -                               int curve0, int curve1);
 - } AudioFadeContext;
 - 
 - enum CurveType { TRI, QSIN, ESIN, HSIN, LOG, IPAR, QUA, CUB, SQU, CBR, PAR, EXP, IQSIN, IHSIN, DESE, DESI, LOSI, NONE, NB_CURVES };
 - 
 - #define OFFSET(x) offsetof(AudioFadeContext, x)
 - #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 - 
 - static int query_formats(AVFilterContext *ctx)
 - {
 -     AVFilterFormats *formats;
 -     AVFilterChannelLayouts *layouts;
 -     static const enum AVSampleFormat sample_fmts[] = {
 -         AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_S16P,
 -         AV_SAMPLE_FMT_S32, AV_SAMPLE_FMT_S32P,
 -         AV_SAMPLE_FMT_FLT, AV_SAMPLE_FMT_FLTP,
 -         AV_SAMPLE_FMT_DBL, AV_SAMPLE_FMT_DBLP,
 -         AV_SAMPLE_FMT_NONE
 -     };
 -     int ret;
 - 
 -     layouts = ff_all_channel_counts();
 -     if (!layouts)
 -         return AVERROR(ENOMEM);
 -     ret = ff_set_common_channel_layouts(ctx, layouts);
 -     if (ret < 0)
 -         return ret;
 - 
 -     formats = ff_make_format_list(sample_fmts);
 -     if (!formats)
 -         return AVERROR(ENOMEM);
 -     ret = ff_set_common_formats(ctx, formats);
 -     if (ret < 0)
 -         return ret;
 - 
 -     formats = ff_all_samplerates();
 -     if (!formats)
 -         return AVERROR(ENOMEM);
 -     return ff_set_common_samplerates(ctx, formats);
 - }
 - 
 - static double fade_gain(int curve, int64_t index, int64_t range)
 - {
 - #define CUBE(a) ((a)*(a)*(a))
 -     double gain;
 - 
 -     gain = av_clipd(1.0 * index / range, 0, 1.0);
 - 
 -     switch (curve) {
 -     case QSIN:
 -         gain = sin(gain * M_PI / 2.0);
 -         break;
 -     case IQSIN:
 -         /* 0.6... = 2 / M_PI */
 -         gain = 0.6366197723675814 * asin(gain);
 -         break;
 -     case ESIN:
 -         gain = 1.0 - cos(M_PI / 4.0 * (CUBE(2.0*gain - 1) + 1));
 -         break;
 -     case HSIN:
 -         gain = (1.0 - cos(gain * M_PI)) / 2.0;
 -         break;
 -     case IHSIN:
 -         /* 0.3... = 1 / M_PI */
 -         gain = 0.3183098861837907 * acos(1 - 2 * gain);
 -         break;
 -     case EXP:
 -         /* -11.5... = 5*ln(0.1) */
 -         gain = exp(-11.512925464970227 * (1 - gain));
 -         break;
 -     case LOG:
 -         gain = av_clipd(1 + 0.2 * log10(gain), 0, 1.0);
 -         break;
 -     case PAR:
 -         gain = 1 - sqrt(1 - gain);
 -         break;
 -     case IPAR:
 -         gain = (1 - (1 - gain) * (1 - gain));
 -         break;
 -     case QUA:
 -         gain *= gain;
 -         break;
 -     case CUB:
 -         gain = CUBE(gain);
 -         break;
 -     case SQU:
 -         gain = sqrt(gain);
 -         break;
 -     case CBR:
 -         gain = cbrt(gain);
 -         break;
 -     case DESE:
 -         gain = gain <= 0.5 ? cbrt(2 * gain) / 2: 1 - cbrt(2 * (1 - gain)) / 2;
 -         break;
 -     case DESI:
 -         gain = gain <= 0.5 ? CUBE(2 * gain) / 2: 1 - CUBE(2 * (1 - gain)) / 2;
 -         break;
 -     case LOSI: {
 -                    const double a = 1. / (1. - 0.787) - 1;
 -                    double A = 1. / (1.0 + exp(0 -((gain-0.5) * a * 2.0)));
 -                    double B = 1. / (1.0 + exp(a));
 -                    double C = 1. / (1.0 + exp(0-a));
 -                    gain = (A - B) / (C - B);
 -                }
 -         break;
 -     case NONE:
 -         gain = 1.0;
 -         break;
 -     }
 - 
 -     return gain;
 - }
 - 
 - #define FADE_PLANAR(name, type)                                             \
 - static void fade_samples_## name ##p(uint8_t **dst, uint8_t * const *src,   \
 -                                      int nb_samples, int channels, int dir, \
 -                                      int64_t start, int64_t range, int curve) \
 - {                                                                           \
 -     int i, c;                                                               \
 -                                                                             \
 -     for (i = 0; i < nb_samples; i++) {                                      \
 -         double gain = fade_gain(curve, start + i * dir, range);             \
 -         for (c = 0; c < channels; c++) {                                    \
 -             type *d = (type *)dst[c];                                       \
 -             const type *s = (type *)src[c];                                 \
 -                                                                             \
 -             d[i] = s[i] * gain;                                             \
 -         }                                                                   \
 -     }                                                                       \
 - }
 - 
 - #define FADE(name, type)                                                    \
 - static void fade_samples_## name (uint8_t **dst, uint8_t * const *src,      \
 -                                   int nb_samples, int channels, int dir,    \
 -                                   int64_t start, int64_t range, int curve)  \
 - {                                                                           \
 -     type *d = (type *)dst[0];                                               \
 -     const type *s = (type *)src[0];                                         \
 -     int i, c, k = 0;                                                        \
 -                                                                             \
 -     for (i = 0; i < nb_samples; i++) {                                      \
 -         double gain = fade_gain(curve, start + i * dir, range);             \
 -         for (c = 0; c < channels; c++, k++)                                 \
 -             d[k] = s[k] * gain;                                             \
 -     }                                                                       \
 - }
 - 
 - FADE_PLANAR(dbl, double)
 - FADE_PLANAR(flt, float)
 - FADE_PLANAR(s16, int16_t)
 - FADE_PLANAR(s32, int32_t)
 - 
 - FADE(dbl, double)
 - FADE(flt, float)
 - FADE(s16, int16_t)
 - FADE(s32, int32_t)
 - 
 - static int config_output(AVFilterLink *outlink)
 - {
 -     AVFilterContext *ctx = outlink->src;
 -     AudioFadeContext *s  = ctx->priv;
 - 
 -     switch (outlink->format) {
 -     case AV_SAMPLE_FMT_DBL:  s->fade_samples = fade_samples_dbl;  break;
 -     case AV_SAMPLE_FMT_DBLP: s->fade_samples = fade_samples_dblp; break;
 -     case AV_SAMPLE_FMT_FLT:  s->fade_samples = fade_samples_flt;  break;
 -     case AV_SAMPLE_FMT_FLTP: s->fade_samples = fade_samples_fltp; break;
 -     case AV_SAMPLE_FMT_S16:  s->fade_samples = fade_samples_s16;  break;
 -     case AV_SAMPLE_FMT_S16P: s->fade_samples = fade_samples_s16p; break;
 -     case AV_SAMPLE_FMT_S32:  s->fade_samples = fade_samples_s32;  break;
 -     case AV_SAMPLE_FMT_S32P: s->fade_samples = fade_samples_s32p; break;
 -     }
 - 
 -     if (s->duration)
 -         s->nb_samples = av_rescale(s->duration, outlink->sample_rate, AV_TIME_BASE);
 -     if (s->start_time)
 -         s->start_sample = av_rescale(s->start_time, outlink->sample_rate, AV_TIME_BASE);
 - 
 -     return 0;
 - }
 - 
 - #if CONFIG_AFADE_FILTER
 - 
 - static const AVOption afade_options[] = {
 -     { "type",         "set the fade direction",                      OFFSET(type),         AV_OPT_TYPE_INT,    {.i64 = 0    }, 0, 1, FLAGS, "type" },
 -     { "t",            "set the fade direction",                      OFFSET(type),         AV_OPT_TYPE_INT,    {.i64 = 0    }, 0, 1, FLAGS, "type" },
 -     { "in",           "fade-in",                                     0,                    AV_OPT_TYPE_CONST,  {.i64 = 0    }, 0, 0, FLAGS, "type" },
 -     { "out",          "fade-out",                                    0,                    AV_OPT_TYPE_CONST,  {.i64 = 1    }, 0, 0, FLAGS, "type" },
 -     { "start_sample", "set number of first sample to start fading",  OFFSET(start_sample), AV_OPT_TYPE_INT64,  {.i64 = 0    }, 0, INT64_MAX, FLAGS },
 -     { "ss",           "set number of first sample to start fading",  OFFSET(start_sample), AV_OPT_TYPE_INT64,  {.i64 = 0    }, 0, INT64_MAX, FLAGS },
 -     { "nb_samples",   "set number of samples for fade duration",     OFFSET(nb_samples),   AV_OPT_TYPE_INT64,  {.i64 = 44100}, 1, INT64_MAX, FLAGS },
 -     { "ns",           "set number of samples for fade duration",     OFFSET(nb_samples),   AV_OPT_TYPE_INT64,  {.i64 = 44100}, 1, INT64_MAX, FLAGS },
 -     { "start_time",   "set time to start fading",                    OFFSET(start_time),   AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT64_MAX, FLAGS },
 -     { "st",           "set time to start fading",                    OFFSET(start_time),   AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT64_MAX, FLAGS },
 -     { "duration",     "set fade duration",                           OFFSET(duration),     AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT64_MAX, FLAGS },
 -     { "d",            "set fade duration",                           OFFSET(duration),     AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, INT64_MAX, FLAGS },
 -     { "curve",        "set fade curve type",                         OFFSET(curve),        AV_OPT_TYPE_INT,    {.i64 = TRI  }, 0, NB_CURVES - 1, FLAGS, "curve" },
 -     { "c",            "set fade curve type",                         OFFSET(curve),        AV_OPT_TYPE_INT,    {.i64 = TRI  }, 0, NB_CURVES - 1, FLAGS, "curve" },
 -     { "tri",          "linear slope",                                0,                    AV_OPT_TYPE_CONST,  {.i64 = TRI  }, 0, 0, FLAGS, "curve" },
 -     { "qsin",         "quarter of sine wave",                        0,                    AV_OPT_TYPE_CONST,  {.i64 = QSIN }, 0, 0, FLAGS, "curve" },
 -     { "esin",         "exponential sine wave",                       0,                    AV_OPT_TYPE_CONST,  {.i64 = ESIN }, 0, 0, FLAGS, "curve" },
 -     { "hsin",         "half of sine wave",                           0,                    AV_OPT_TYPE_CONST,  {.i64 = HSIN }, 0, 0, FLAGS, "curve" },
 -     { "log",          "logarithmic",                                 0,                    AV_OPT_TYPE_CONST,  {.i64 = LOG  }, 0, 0, FLAGS, "curve" },
 -     { "ipar",         "inverted parabola",                           0,                    AV_OPT_TYPE_CONST,  {.i64 = IPAR }, 0, 0, FLAGS, "curve" },
 -     { "qua",          "quadratic",                                   0,                    AV_OPT_TYPE_CONST,  {.i64 = QUA  }, 0, 0, FLAGS, "curve" },
 -     { "cub",          "cubic",                                       0,                    AV_OPT_TYPE_CONST,  {.i64 = CUB  }, 0, 0, FLAGS, "curve" },
 -     { "squ",          "square root",                                 0,                    AV_OPT_TYPE_CONST,  {.i64 = SQU  }, 0, 0, FLAGS, "curve" },
 -     { "cbr",          "cubic root",                                  0,                    AV_OPT_TYPE_CONST,  {.i64 = CBR  }, 0, 0, FLAGS, "curve" },
 -     { "par",          "parabola",                                    0,                    AV_OPT_TYPE_CONST,  {.i64 = PAR  }, 0, 0, FLAGS, "curve" },
 -     { "exp",          "exponential",                                 0,                    AV_OPT_TYPE_CONST,  {.i64 = EXP  }, 0, 0, FLAGS, "curve" },
 -     { "iqsin",        "inverted quarter of sine wave",               0,                    AV_OPT_TYPE_CONST,  {.i64 = IQSIN}, 0, 0, FLAGS, "curve" },
 -     { "ihsin",        "inverted half of sine wave",                  0,                    AV_OPT_TYPE_CONST,  {.i64 = IHSIN}, 0, 0, FLAGS, "curve" },
 -     { "dese",         "double-exponential seat",                     0,                    AV_OPT_TYPE_CONST,  {.i64 = DESE }, 0, 0, FLAGS, "curve" },
 -     { "desi",         "double-exponential sigmoid",                  0,                    AV_OPT_TYPE_CONST,  {.i64 = DESI }, 0, 0, FLAGS, "curve" },
 -     { "losi",         "logistic sigmoid",                            0,                    AV_OPT_TYPE_CONST,  {.i64 = LOSI }, 0, 0, FLAGS, "curve" },
 -     { "nofade",       "no fade; keep audio as-is",                   0,                    AV_OPT_TYPE_CONST,  {.i64 = NONE }, 0, 0, FLAGS, "curve" },
 -     { NULL }
 - };
 - 
 - AVFILTER_DEFINE_CLASS(afade);
 - 
 - static av_cold int init(AVFilterContext *ctx)
 - {
 -     AudioFadeContext *s = ctx->priv;
 - 
 -     if (INT64_MAX - s->nb_samples < s->start_sample)
 -         return AVERROR(EINVAL);
 - 
 -     return 0;
 - }
 - 
 - static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
 - {
 -     AudioFadeContext *s     = inlink->dst->priv;
 -     AVFilterLink *outlink   = inlink->dst->outputs[0];
 -     int nb_samples          = buf->nb_samples;
 -     AVFrame *out_buf;
 -     int64_t cur_sample = av_rescale_q(buf->pts, inlink->time_base, (AVRational){1, inlink->sample_rate});
 - 
 -     if ((!s->type && (s->start_sample + s->nb_samples < cur_sample)) ||
 -         ( s->type && (cur_sample + nb_samples < s->start_sample)))
 -         return ff_filter_frame(outlink, buf);
 - 
 -     if (av_frame_is_writable(buf)) {
 -         out_buf = buf;
 -     } else {
 -         out_buf = ff_get_audio_buffer(outlink, nb_samples);
 -         if (!out_buf)
 -             return AVERROR(ENOMEM);
 -         av_frame_copy_props(out_buf, buf);
 -     }
 - 
 -     if ((!s->type && (cur_sample + nb_samples < s->start_sample)) ||
 -         ( s->type && (s->start_sample + s->nb_samples < cur_sample))) {
 -         av_samples_set_silence(out_buf->extended_data, 0, nb_samples,
 -                                out_buf->channels, out_buf->format);
 -     } else {
 -         int64_t start;
 - 
 -         if (!s->type)
 -             start = cur_sample - s->start_sample;
 -         else
 -             start = s->start_sample + s->nb_samples - cur_sample;
 - 
 -         s->fade_samples(out_buf->extended_data, buf->extended_data,
 -                         nb_samples, buf->channels,
 -                         s->type ? -1 : 1, start,
 -                         s->nb_samples, s->curve);
 -     }
 - 
 -     if (buf != out_buf)
 -         av_frame_free(&buf);
 - 
 -     return ff_filter_frame(outlink, out_buf);
 - }
 - 
 - static const AVFilterPad avfilter_af_afade_inputs[] = {
 -     {
 -         .name         = "default",
 -         .type         = AVMEDIA_TYPE_AUDIO,
 -         .filter_frame = filter_frame,
 -     },
 -     { NULL }
 - };
 - 
 - static const AVFilterPad avfilter_af_afade_outputs[] = {
 -     {
 -         .name         = "default",
 -         .type         = AVMEDIA_TYPE_AUDIO,
 -         .config_props = config_output,
 -     },
 -     { NULL }
 - };
 - 
 - AVFilter ff_af_afade = {
 -     .name          = "afade",
 -     .description   = NULL_IF_CONFIG_SMALL("Fade in/out input audio."),
 -     .query_formats = query_formats,
 -     .priv_size     = sizeof(AudioFadeContext),
 -     .init          = init,
 -     .inputs        = avfilter_af_afade_inputs,
 -     .outputs       = avfilter_af_afade_outputs,
 -     .priv_class    = &afade_class,
 -     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
 - };
 - 
 - #endif /* CONFIG_AFADE_FILTER */
 - 
 - #if CONFIG_ACROSSFADE_FILTER
 - 
 - static const AVOption acrossfade_options[] = {
 -     { "nb_samples",   "set number of samples for cross fade duration", OFFSET(nb_samples),   AV_OPT_TYPE_INT,    {.i64 = 44100}, 1, INT32_MAX/10, FLAGS },
 -     { "ns",           "set number of samples for cross fade duration", OFFSET(nb_samples),   AV_OPT_TYPE_INT,    {.i64 = 44100}, 1, INT32_MAX/10, FLAGS },
 -     { "duration",     "set cross fade duration",                       OFFSET(duration),     AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, 60000000, FLAGS },
 -     { "d",            "set cross fade duration",                       OFFSET(duration),     AV_OPT_TYPE_DURATION, {.i64 = 0. }, 0, 60000000, FLAGS },
 -     { "overlap",      "overlap 1st stream end with 2nd stream start",  OFFSET(overlap),      AV_OPT_TYPE_BOOL,   {.i64 = 1    }, 0,  1, FLAGS },
 -     { "o",            "overlap 1st stream end with 2nd stream start",  OFFSET(overlap),      AV_OPT_TYPE_BOOL,   {.i64 = 1    }, 0,  1, FLAGS },
 -     { "curve1",       "set fade curve type for 1st stream",            OFFSET(curve),        AV_OPT_TYPE_INT,    {.i64 = TRI  }, 0, NB_CURVES - 1, FLAGS, "curve" },
 -     { "c1",           "set fade curve type for 1st stream",            OFFSET(curve),        AV_OPT_TYPE_INT,    {.i64 = TRI  }, 0, NB_CURVES - 1, FLAGS, "curve" },
 -     {     "tri",      "linear slope",                                  0,                    AV_OPT_TYPE_CONST,  {.i64 = TRI  }, 0, 0, FLAGS, "curve" },
 -     {     "qsin",     "quarter of sine wave",                          0,                    AV_OPT_TYPE_CONST,  {.i64 = QSIN }, 0, 0, FLAGS, "curve" },
 -     {     "esin",     "exponential sine wave",                         0,                    AV_OPT_TYPE_CONST,  {.i64 = ESIN }, 0, 0, FLAGS, "curve" },
 -     {     "hsin",     "half of sine wave",                             0,                    AV_OPT_TYPE_CONST,  {.i64 = HSIN }, 0, 0, FLAGS, "curve" },
 -     {     "log",      "logarithmic",                                   0,                    AV_OPT_TYPE_CONST,  {.i64 = LOG  }, 0, 0, FLAGS, "curve" },
 -     {     "ipar",     "inverted parabola",                             0,                    AV_OPT_TYPE_CONST,  {.i64 = IPAR }, 0, 0, FLAGS, "curve" },
 -     {     "qua",      "quadratic",                                     0,                    AV_OPT_TYPE_CONST,  {.i64 = QUA  }, 0, 0, FLAGS, "curve" },
 -     {     "cub",      "cubic",                                         0,                    AV_OPT_TYPE_CONST,  {.i64 = CUB  }, 0, 0, FLAGS, "curve" },
 -     {     "squ",      "square root",                                   0,                    AV_OPT_TYPE_CONST,  {.i64 = SQU  }, 0, 0, FLAGS, "curve" },
 -     {     "cbr",      "cubic root",                                    0,                    AV_OPT_TYPE_CONST,  {.i64 = CBR  }, 0, 0, FLAGS, "curve" },
 -     {     "par",      "parabola",                                      0,                    AV_OPT_TYPE_CONST,  {.i64 = PAR  }, 0, 0, FLAGS, "curve" },
 -     {     "exp",      "exponential",                                   0,                    AV_OPT_TYPE_CONST,  {.i64 = EXP  }, 0, 0, FLAGS, "curve" },
 -     {     "iqsin",    "inverted quarter of sine wave",                 0,                    AV_OPT_TYPE_CONST,  {.i64 = IQSIN}, 0, 0, FLAGS, "curve" },
 -     {     "ihsin",    "inverted half of sine wave",                    0,                    AV_OPT_TYPE_CONST,  {.i64 = IHSIN}, 0, 0, FLAGS, "curve" },
 -     {     "dese",     "double-exponential seat",                       0,                    AV_OPT_TYPE_CONST,  {.i64 = DESE }, 0, 0, FLAGS, "curve" },
 -     {     "desi",     "double-exponential sigmoid",                    0,                    AV_OPT_TYPE_CONST,  {.i64 = DESI }, 0, 0, FLAGS, "curve" },
 -     {     "losi",     "logistic sigmoid",                              0,                    AV_OPT_TYPE_CONST,  {.i64 = LOSI }, 0, 0, FLAGS, "curve" },
 -     {     "nofade",   "no fade; keep audio as-is",                     0,                    AV_OPT_TYPE_CONST,  {.i64 = NONE }, 0, 0, FLAGS, "curve" },
 -     { "curve2",       "set fade curve type for 2nd stream",            OFFSET(curve2),       AV_OPT_TYPE_INT,    {.i64 = TRI  }, 0, NB_CURVES - 1, FLAGS, "curve" },
 -     { "c2",           "set fade curve type for 2nd stream",            OFFSET(curve2),       AV_OPT_TYPE_INT,    {.i64 = TRI  }, 0, NB_CURVES - 1, FLAGS, "curve" },
 -     { NULL }
 - };
 - 
 - AVFILTER_DEFINE_CLASS(acrossfade);
 - 
 - #define CROSSFADE_PLANAR(name, type)                                           \
 - static void crossfade_samples_## name ##p(uint8_t **dst, uint8_t * const *cf0, \
 -                                           uint8_t * const *cf1,                \
 -                                           int nb_samples, int channels,        \
 -                                           int curve0, int curve1)              \
 - {                                                                              \
 -     int i, c;                                                                  \
 -                                                                                \
 -     for (i = 0; i < nb_samples; i++) {                                         \
 -         double gain0 = fade_gain(curve0, nb_samples - 1 - i, nb_samples);      \
 -         double gain1 = fade_gain(curve1, i, nb_samples);                       \
 -         for (c = 0; c < channels; c++) {                                       \
 -             type *d = (type *)dst[c];                                          \
 -             const type *s0 = (type *)cf0[c];                                   \
 -             const type *s1 = (type *)cf1[c];                                   \
 -                                                                                \
 -             d[i] = s0[i] * gain0 + s1[i] * gain1;                              \
 -         }                                                                      \
 -     }                                                                          \
 - }
 - 
 - #define CROSSFADE(name, type)                                               \
 - static void crossfade_samples_## name (uint8_t **dst, uint8_t * const *cf0, \
 -                                        uint8_t * const *cf1,                \
 -                                        int nb_samples, int channels,        \
 -                                        int curve0, int curve1)              \
 - {                                                                           \
 -     type *d = (type *)dst[0];                                               \
 -     const type *s0 = (type *)cf0[0];                                        \
 -     const type *s1 = (type *)cf1[0];                                        \
 -     int i, c, k = 0;                                                        \
 -                                                                             \
 -     for (i = 0; i < nb_samples; i++) {                                      \
 -         double gain0 = fade_gain(curve0, nb_samples - 1 - i, nb_samples);   \
 -         double gain1 = fade_gain(curve1, i, nb_samples);                    \
 -         for (c = 0; c < channels; c++, k++)                                 \
 -             d[k] = s0[k] * gain0 + s1[k] * gain1;                           \
 -     }                                                                       \
 - }
 - 
 - CROSSFADE_PLANAR(dbl, double)
 - CROSSFADE_PLANAR(flt, float)
 - CROSSFADE_PLANAR(s16, int16_t)
 - CROSSFADE_PLANAR(s32, int32_t)
 - 
 - CROSSFADE(dbl, double)
 - CROSSFADE(flt, float)
 - CROSSFADE(s16, int16_t)
 - CROSSFADE(s32, int32_t)
 - 
 - static int activate(AVFilterContext *ctx)
 - {
 -     AudioFadeContext *s   = ctx->priv;
 -     AVFilterLink *outlink = ctx->outputs[0];
 -     AVFrame *in = NULL, *out, *cf[2] = { NULL };
 -     int ret = 0, nb_samples, status;
 -     int64_t pts;
 - 
 -     FF_FILTER_FORWARD_STATUS_BACK_ALL(outlink, ctx);
 - 
 -     if (s->crossfade_is_over) {
 -         ret = ff_inlink_consume_frame(ctx->inputs[1], &in);
 -         if (ret < 0) {
 -             return ret;
 -         } else if (ff_inlink_acknowledge_status(ctx->inputs[1], &status, &pts)) {
 -             ff_outlink_set_status(ctx->outputs[0], status, pts);
 -             return 0;
 -         } else {
 -             if (ff_outlink_frame_wanted(ctx->outputs[0]) && !in) {
 -                 ff_inlink_request_frame(ctx->inputs[1]);
 -                 return 0;
 -             }
 -         }
 -         in->pts = s->pts;
 -         s->pts += av_rescale_q(in->nb_samples,
 -             (AVRational){ 1, outlink->sample_rate }, outlink->time_base);
 -         return ff_filter_frame(outlink, in);
 -     }
 - 
 -     if (ff_inlink_queued_samples(ctx->inputs[0]) > s->nb_samples) {
 -         nb_samples = ff_inlink_queued_samples(ctx->inputs[0]) - s->nb_samples;
 -         if (nb_samples > 0) {
 -             ret = ff_inlink_consume_samples(ctx->inputs[0], nb_samples, nb_samples, &in);
 -             if (ret < 0) {
 -                 return ret;
 -             }
 -         }
 -         in->pts = s->pts;
 -         s->pts += av_rescale_q(in->nb_samples,
 -             (AVRational){ 1, outlink->sample_rate }, outlink->time_base);
 -         return ff_filter_frame(outlink, in);
 -     } else if (ff_inlink_queued_samples(ctx->inputs[1]) >= s->nb_samples) {
 -         if (s->overlap) {
 -             out = ff_get_audio_buffer(outlink, s->nb_samples);
 -             if (!out)
 -                 return AVERROR(ENOMEM);
 - 
 -             ret = ff_inlink_consume_samples(ctx->inputs[0], s->nb_samples, s->nb_samples, &cf[0]);
 -             if (ret < 0) {
 -                 av_frame_free(&out);
 -                 return ret;
 -             }
 - 
 -             ret = ff_inlink_consume_samples(ctx->inputs[1], s->nb_samples, s->nb_samples, &cf[1]);
 -             if (ret < 0) {
 -                 av_frame_free(&out);
 -                 return ret;
 -             }
 - 
 -             s->crossfade_samples(out->extended_data, cf[0]->extended_data,
 -                                  cf[1]->extended_data,
 -                                  s->nb_samples, out->channels,
 -                                  s->curve, s->curve2);
 -             out->pts = s->pts;
 -             s->pts += av_rescale_q(s->nb_samples,
 -                 (AVRational){ 1, outlink->sample_rate }, outlink->time_base);
 -             s->crossfade_is_over = 1;
 -             av_frame_free(&cf[0]);
 -             av_frame_free(&cf[1]);
 -             return ff_filter_frame(outlink, out);
 -         } else {
 -             out = ff_get_audio_buffer(outlink, s->nb_samples);
 -             if (!out)
 -                 return AVERROR(ENOMEM);
 - 
 -             ret = ff_inlink_consume_samples(ctx->inputs[0], s->nb_samples, s->nb_samples, &cf[0]);
 -             if (ret < 0) {
 -                 av_frame_free(&out);
 -                 return ret;
 -             }
 - 
 -             s->fade_samples(out->extended_data, cf[0]->extended_data, s->nb_samples,
 -                             outlink->channels, -1, s->nb_samples - 1, s->nb_samples, s->curve);
 -             out->pts = s->pts;
 -             s->pts += av_rescale_q(s->nb_samples,
 -                 (AVRational){ 1, outlink->sample_rate }, outlink->time_base);
 -             av_frame_free(&cf[0]);
 -             ret = ff_filter_frame(outlink, out);
 -             if (ret < 0)
 -                 return ret;
 - 
 -             out = ff_get_audio_buffer(outlink, s->nb_samples);
 -             if (!out)
 -                 return AVERROR(ENOMEM);
 - 
 -             ret = ff_inlink_consume_samples(ctx->inputs[1], s->nb_samples, s->nb_samples, &cf[1]);
 -             if (ret < 0) {
 -                 av_frame_free(&out);
 -                 return ret;
 -             }
 - 
 -             s->fade_samples(out->extended_data, cf[1]->extended_data, s->nb_samples,
 -                             outlink->channels, 1, 0, s->nb_samples, s->curve2);
 -             out->pts = s->pts;
 -             s->pts += av_rescale_q(s->nb_samples,
 -                 (AVRational){ 1, outlink->sample_rate }, outlink->time_base);
 -             s->crossfade_is_over = 1;
 -             av_frame_free(&cf[1]);
 -             return ff_filter_frame(outlink, out);
 -         }
 -     } else if (ff_outlink_frame_wanted(ctx->outputs[0])) {
 -         if (!s->cf0_eof && ff_outlink_get_status(ctx->inputs[0])) {
 -             s->cf0_eof = 1;
 -         }
 -         if (ff_outlink_get_status(ctx->inputs[1])) {
 -             ff_outlink_set_status(ctx->outputs[0], AVERROR_EOF, AV_NOPTS_VALUE);
 -             return 0;
 -         }
 -         if (!s->cf0_eof)
 -             ff_inlink_request_frame(ctx->inputs[0]);
 -         else
 -             ff_inlink_request_frame(ctx->inputs[1]);
 -         return 0;
 -     }
 - 
 -     return ret;
 - }
 - 
 - static int acrossfade_config_output(AVFilterLink *outlink)
 - {
 -     AVFilterContext *ctx = outlink->src;
 -     AudioFadeContext *s  = ctx->priv;
 - 
 -     if (ctx->inputs[0]->sample_rate != ctx->inputs[1]->sample_rate) {
 -         av_log(ctx, AV_LOG_ERROR,
 -                "Inputs must have the same sample rate "
 -                "%d for in0 vs %d for in1\n",
 -                ctx->inputs[0]->sample_rate, ctx->inputs[1]->sample_rate);
 -         return AVERROR(EINVAL);
 -     }
 - 
 -     outlink->sample_rate = ctx->inputs[0]->sample_rate;
 -     outlink->time_base   = ctx->inputs[0]->time_base;
 -     outlink->channel_layout = ctx->inputs[0]->channel_layout;
 -     outlink->channels = ctx->inputs[0]->channels;
 - 
 -     switch (outlink->format) {
 -     case AV_SAMPLE_FMT_DBL:  s->crossfade_samples = crossfade_samples_dbl;  break;
 -     case AV_SAMPLE_FMT_DBLP: s->crossfade_samples = crossfade_samples_dblp; break;
 -     case AV_SAMPLE_FMT_FLT:  s->crossfade_samples = crossfade_samples_flt;  break;
 -     case AV_SAMPLE_FMT_FLTP: s->crossfade_samples = crossfade_samples_fltp; break;
 -     case AV_SAMPLE_FMT_S16:  s->crossfade_samples = crossfade_samples_s16;  break;
 -     case AV_SAMPLE_FMT_S16P: s->crossfade_samples = crossfade_samples_s16p; break;
 -     case AV_SAMPLE_FMT_S32:  s->crossfade_samples = crossfade_samples_s32;  break;
 -     case AV_SAMPLE_FMT_S32P: s->crossfade_samples = crossfade_samples_s32p; break;
 -     }
 - 
 -     config_output(outlink);
 - 
 -     return 0;
 - }
 - 
 - static const AVFilterPad avfilter_af_acrossfade_inputs[] = {
 -     {
 -         .name         = "crossfade0",
 -         .type         = AVMEDIA_TYPE_AUDIO,
 -     },
 -     {
 -         .name         = "crossfade1",
 -         .type         = AVMEDIA_TYPE_AUDIO,
 -     },
 -     { NULL }
 - };
 - 
 - static const AVFilterPad avfilter_af_acrossfade_outputs[] = {
 -     {
 -         .name          = "default",
 -         .type          = AVMEDIA_TYPE_AUDIO,
 -         .config_props  = acrossfade_config_output,
 -     },
 -     { NULL }
 - };
 - 
 - AVFilter ff_af_acrossfade = {
 -     .name          = "acrossfade",
 -     .description   = NULL_IF_CONFIG_SMALL("Cross fade two input audio streams."),
 -     .query_formats = query_formats,
 -     .priv_size     = sizeof(AudioFadeContext),
 -     .activate      = activate,
 -     .priv_class    = &acrossfade_class,
 -     .inputs        = avfilter_af_acrossfade_inputs,
 -     .outputs       = avfilter_af_acrossfade_outputs,
 - };
 - 
 - #endif /* CONFIG_ACROSSFADE_FILTER */
 
 
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