/*
  * Copyright (C) 2017 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
  */
 
 #include "libavutil/common.h"
 #include "libavutil/opt.h"
 #include "internal.h"
 
 typedef struct VFRDETContext {
     const AVClass *class;
 
     int64_t prev_pts;
     int64_t delta;
     int64_t min_delta;
     int64_t max_delta;
 
     uint64_t vfr;
     uint64_t cfr;
 } VFRDETContext;
 
 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
 {
     AVFilterContext *ctx = inlink->dst;
     VFRDETContext *s = ctx->priv;
 
     if (s->prev_pts != AV_NOPTS_VALUE) {
         int64_t delta = in->pts - s->prev_pts;
 
         if (s->delta == AV_NOPTS_VALUE) {
             s->delta = delta;
         }
 
         if (s->delta != delta) {
             s->vfr++;
             s->delta = delta;
             s->min_delta = FFMIN(delta, s->min_delta);
             s->max_delta = FFMAX(delta, s->max_delta);
         } else {
             s->cfr++;
         }
     }
 
     s->prev_pts = in->pts;
 
     return ff_filter_frame(ctx->outputs[0], in);
 }
 
 static av_cold int init(AVFilterContext *ctx)
 {
     VFRDETContext *s = ctx->priv;
 
     s->prev_pts = AV_NOPTS_VALUE;
     s->delta    = AV_NOPTS_VALUE;
     s->min_delta = INT64_MAX;
     s->max_delta = INT64_MIN;
 
     return 0;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     VFRDETContext *s = ctx->priv;
 
     av_log(ctx, AV_LOG_INFO, "VFR:%f (%"PRIu64"/%"PRIu64")", s->vfr / (float)(s->vfr + s->cfr), s->vfr, s->cfr);
     if (s->vfr)
         av_log(ctx, AV_LOG_INFO, " min: %"PRId64" max: %"PRId64")", s->min_delta, s->max_delta);
     av_log(ctx, AV_LOG_INFO, "\n");
 }
 
 static const AVFilterPad vfrdet_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame,
     },
     { NULL }
 };
 
 static const AVFilterPad vfrdet_outputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_VIDEO,
     },
     { NULL }
 };
 
 AVFilter ff_vf_vfrdet = {
     .name        = "vfrdet",
     .description = NULL_IF_CONFIG_SMALL("Variable frame rate detect filter."),
     .priv_size   = sizeof(VFRDETContext),
     .init        = init,
     .uninit      = uninit,
     .inputs      = vfrdet_inputs,
     .outputs     = vfrdet_outputs,
 };