/*

  * Copyright 2007 Bobby Bingham
  * Copyright 2012 Robert Nagy <ronag89 gmail com>
  * Copyright 2012 Anton Khirnov <anton khirnov net>
  *

  * 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
  * a filter enforcing given constant framerate
  */
 

 #include <float.h>

 #include <stdint.h>

 #include "libavutil/common.h"

 #include "libavutil/fifo.h"
 #include "libavutil/mathematics.h"
 #include "libavutil/opt.h"
 #include "libavutil/parseutils.h"
 

 #define FF_INTERNAL_FIELDS 1
 #include "framequeue.h"

 #include "avfilter.h"

 #include "internal.h"
 #include "video.h"

 enum EOFAction {
     EOF_ACTION_ROUND,
     EOF_ACTION_PASS,
     EOF_ACTION_NB
 };
 

 typedef struct FPSContext {
     const AVClass *class;
 
     AVFifoBuffer *fifo;     ///< store frames until we get two successive timestamps
 
     /* timestamps in input timebase */
     int64_t first_pts;      ///< pts of the first frame that arrived on this filter
 

     double start_time;      ///< pts, in seconds, of the expected first frame
 

     AVRational framerate;   ///< target framerate

     int rounding;           ///< AVRounding method for timestamps

     int eof_action;         ///< action performed for last frame in FIFO

 
     /* statistics */
     int frames_in;             ///< number of frames on input
     int frames_out;            ///< number of frames on output
     int dup;                   ///< number of frames duplicated
     int drop;                  ///< number of framed dropped
 } FPSContext;
 
 #define OFFSET(x) offsetof(FPSContext, x)
 #define V AV_OPT_FLAG_VIDEO_PARAM

 #define F AV_OPT_FLAG_FILTERING_PARAM

 static const AVOption fps_options[] = {

     { "fps", "A string describing desired output framerate", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, { .str = "25" }, 0, INT_MAX, V|F },

     { "start_time", "Assume the first PTS should be this value.", OFFSET(start_time), AV_OPT_TYPE_DOUBLE, { .dbl = DBL_MAX}, -DBL_MAX, DBL_MAX, V|F },

     { "round", "set rounding method for timestamps", OFFSET(rounding), AV_OPT_TYPE_INT, { .i64 = AV_ROUND_NEAR_INF }, 0, 5, V|F, "round" },

         { "zero", "round towards 0",                 0, AV_OPT_TYPE_CONST, { .i64 = AV_ROUND_ZERO     }, 0, 0, V|F, "round" },
         { "inf",  "round away from 0",               0, AV_OPT_TYPE_CONST, { .i64 = AV_ROUND_INF      }, 0, 0, V|F, "round" },
         { "down", "round towards -infty",            0, AV_OPT_TYPE_CONST, { .i64 = AV_ROUND_DOWN     }, 0, 0, V|F, "round" },
         { "up",   "round towards +infty",            0, AV_OPT_TYPE_CONST, { .i64 = AV_ROUND_UP       }, 0, 0, V|F, "round" },
         { "near", "round to nearest",                0, AV_OPT_TYPE_CONST, { .i64 = AV_ROUND_NEAR_INF }, 0, 0, V|F, "round" },

     { "eof_action", "action performed for last frame", OFFSET(eof_action), AV_OPT_TYPE_INT, { .i64 = EOF_ACTION_ROUND }, 0, EOF_ACTION_NB-1, V|F, "eof_action" },
         { "round", "round similar to other frames",  0, AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_ROUND }, 0, 0, V|F, "eof_action" },
         { "pass",  "pass through last frame",        0, AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_PASS  }, 0, 0, V|F, "eof_action" },

     { NULL }

 };
 

 AVFILTER_DEFINE_CLASS(fps);

 static av_cold int init(AVFilterContext *ctx)

 {
     FPSContext *s = ctx->priv;
 

     if (!(s->fifo = av_fifo_alloc_array(2, sizeof(AVFrame*))))

         return AVERROR(ENOMEM);
 

     s->first_pts    = AV_NOPTS_VALUE;

     av_log(ctx, AV_LOG_VERBOSE, "fps=%d/%d\n", s->framerate.num, s->framerate.den);
     return 0;
 }
 
 static void flush_fifo(AVFifoBuffer *fifo)
 {
     while (av_fifo_size(fifo)) {

         AVFrame *tmp;

         av_fifo_generic_read(fifo, &tmp, sizeof(tmp), NULL);

         av_frame_free(&tmp);

     }
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     FPSContext *s = ctx->priv;
     if (s->fifo) {

         s->drop += av_fifo_size(s->fifo) / sizeof(AVFrame*);

         flush_fifo(s->fifo);

         av_fifo_freep(&s->fifo);

     }
 
     av_log(ctx, AV_LOG_VERBOSE, "%d frames in, %d frames out; %d frames dropped, "
            "%d frames duplicated.\n", s->frames_in, s->frames_out, s->drop, s->dup);
 }
 
 static int config_props(AVFilterLink* link)
 {
     FPSContext   *s = link->src->priv;
 

     link->time_base = av_inv_q(s->framerate);

     link->frame_rate= s->framerate;

     link->w         = link->src->inputs[0]->w;
     link->h         = link->src->inputs[0]->h;
 
     return 0;
 }
 
 static int request_frame(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     FPSContext        *s = ctx->priv;

     int ret;

     ret = ff_request_frame(ctx->inputs[0]);

 
     /* flush the fifo */
     if (ret == AVERROR_EOF && av_fifo_size(s->fifo)) {
         int i;
         for (i = 0; av_fifo_size(s->fifo); i++) {

             AVFrame *buf;

 
             av_fifo_generic_read(s->fifo, &buf, sizeof(buf), NULL);

             if (av_fifo_size(s->fifo)) {
                 buf->pts = av_rescale_q(s->first_pts, ctx->inputs[0]->time_base,
                                         outlink->time_base) + s->frames_out;
 
                 if ((ret = ff_filter_frame(outlink, buf)) < 0)
                     return ret;
 
                 s->frames_out++;
             } else {
                 /* This is the last frame, we may have to duplicate it to match
                  * the last frame duration */
                 int j;

                 int eof_rounding = (s->eof_action == EOF_ACTION_PASS) ? AV_ROUND_UP : s->rounding;

                 int delta = av_rescale_q_rnd(ctx->inputs[0]->current_pts - s->first_pts,
                                              ctx->inputs[0]->time_base,

                                              outlink->time_base, eof_rounding) - s->frames_out;
                 av_log(ctx, AV_LOG_DEBUG, "EOF frames_out:%d delta:%d\n", s->frames_out, delta);

                 /* if the delta is equal to 1, it means we just need to output
                  * the last frame. Greater than 1 means we will need duplicate
                  * delta-1 frames */
                 if (delta > 0 ) {
                     for (j = 0; j < delta; j++) {
                         AVFrame *dup = av_frame_clone(buf);
 
                         av_log(ctx, AV_LOG_DEBUG, "Duplicating frame.\n");
                         dup->pts = av_rescale_q(s->first_pts, ctx->inputs[0]->time_base,
                                                 outlink->time_base) + s->frames_out;
 
                         if ((ret = ff_filter_frame(outlink, dup)) < 0)
                             return ret;
 
                         s->frames_out++;
                         if (j > 0) s->dup++;
                     }

                     av_frame_free(&buf);

                 } else {
                     /* for delta less or equal to 0, we should drop the frame,
                      * otherwise, we will have one or more extra frames */
                     av_frame_free(&buf);
                     s->drop++;
                 }
             }

         }
         return 0;
     }
 
     return ret;
 }
 

 static int write_to_fifo(AVFifoBuffer *fifo, AVFrame *buf)

 {
     int ret;
 
     if (!av_fifo_space(fifo) &&

         (ret = av_fifo_realloc2(fifo, 2*av_fifo_size(fifo)))) {

         av_frame_free(&buf);

         return ret;

     }

 
     av_fifo_generic_write(fifo, &buf, sizeof(buf), NULL);
     return 0;
 }
 

 static int filter_frame(AVFilterLink *inlink, AVFrame *buf)

 {
     AVFilterContext    *ctx = inlink->dst;
     FPSContext           *s = ctx->priv;
     AVFilterLink   *outlink = ctx->outputs[0];
     int64_t delta;

     int i, ret;

 
     s->frames_in++;
     /* discard frames until we get the first timestamp */

     if (s->first_pts == AV_NOPTS_VALUE) {

         if (buf->pts != AV_NOPTS_VALUE) {

             ret = write_to_fifo(s->fifo, buf);
             if (ret < 0)
                 return ret;
 

             if (s->start_time != DBL_MAX && s->start_time != AV_NOPTS_VALUE) {

                 double first_pts = s->start_time * AV_TIME_BASE;
                 first_pts = FFMIN(FFMAX(first_pts, INT64_MIN), INT64_MAX);

                 s->first_pts = av_rescale_q(first_pts, AV_TIME_BASE_Q,

                                                      inlink->time_base);
                 av_log(ctx, AV_LOG_VERBOSE, "Set first pts to (in:%"PRId64" out:%"PRId64")\n",
                        s->first_pts, av_rescale_q(first_pts, AV_TIME_BASE_Q,
                                                   outlink->time_base));
             } else {

                 s->first_pts = buf->pts;

             }

         } else {
             av_log(ctx, AV_LOG_WARNING, "Discarding initial frame(s) with no "
                    "timestamp.\n");

             av_frame_free(&buf);

             s->drop++;
         }

         return 0;

     }
 
     /* now wait for the next timestamp */

     if (buf->pts == AV_NOPTS_VALUE || av_fifo_size(s->fifo) <= 0) {

         return write_to_fifo(s->fifo, buf);

     }
 
     /* number of output frames */

     delta = av_rescale_q_rnd(buf->pts - s->first_pts, inlink->time_base,
                              outlink->time_base, s->rounding) - s->frames_out ;

 
     if (delta < 1) {

         /* drop everything buffered except the last */

         int drop = av_fifo_size(s->fifo)/sizeof(AVFrame*);

 
         av_log(ctx, AV_LOG_DEBUG, "Dropping %d frame(s).\n", drop);
         s->drop += drop;
 
         flush_fifo(s->fifo);

         ret = write_to_fifo(s->fifo, buf);

         return ret;

     }
 
     /* can output >= 1 frames */
     for (i = 0; i < delta; i++) {

         AVFrame *buf_out;

         av_fifo_generic_read(s->fifo, &buf_out, sizeof(buf_out), NULL);
 
         /* duplicate the frame if needed */
         if (!av_fifo_size(s->fifo) && i < delta - 1) {

             AVFrame *dup = av_frame_clone(buf_out);

             av_log(ctx, AV_LOG_DEBUG, "Duplicating frame.\n");

             if (dup)
                 ret = write_to_fifo(s->fifo, dup);
             else
                 ret = AVERROR(ENOMEM);
 
             if (ret < 0) {

                 av_frame_free(&buf_out);
                 av_frame_free(&buf);

                 return ret;
             }
 

             s->dup++;
         }
 
         buf_out->pts = av_rescale_q(s->first_pts, inlink->time_base,
                                     outlink->time_base) + s->frames_out;
 

         if ((ret = ff_filter_frame(outlink, buf_out)) < 0) {

             av_frame_free(&buf);

             return ret;
         }
 

         s->frames_out++;
     }
     flush_fifo(s->fifo);
 

     ret = write_to_fifo(s->fifo, buf);
 
     return ret;

 }
 

 static const AVFilterPad avfilter_vf_fps_inputs[] = {
     {

         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,

         .filter_frame = filter_frame,

     },
     { NULL }
 };
 
 static const AVFilterPad avfilter_vf_fps_outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
         .request_frame = request_frame,
         .config_props  = config_props
     },
     { NULL }
 };
 

 AVFilter ff_vf_fps = {

     .name        = "fps",

     .description = NULL_IF_CONFIG_SMALL("Force constant framerate."),

     .init        = init,
     .uninit      = uninit,
     .priv_size   = sizeof(FPSContext),
     .priv_class  = &fps_class,
     .inputs      = avfilter_vf_fps_inputs,
     .outputs     = avfilter_vf_fps_outputs,

 };