/*
  * Copyright (c) 2010 Stefano Sabatini
  * Copyright (c) 2008 Victor Paesa
  *
  * 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
  * video presentation timestamp (PTS) modification filter
  */
 
 /* #define DEBUG */
 
 #include "libavutil/eval.h"

 #include "libavutil/mathematics.h"

 #include "avfilter.h"
 

 static const char * const var_names[] = {

     "INTERLACED",  ///< tell if the current frame is interlaced
     "N",           ///< frame number (starting at zero)
     "POS",         ///< original position in the file of the frame
     "PREV_INPTS",  ///< previous  input PTS
     "PREV_OUTPTS", ///< previous output PTS
     "PTS",         ///< original pts in the file of the frame
     "STARTPTS",   ///< PTS at start of movie
     "TB",          ///< timebase
     NULL
 };
 
 enum var_name {
     VAR_INTERLACED,
     VAR_N,
     VAR_POS,
     VAR_PREV_INPTS,
     VAR_PREV_OUTPTS,
     VAR_PTS,
     VAR_STARTPTS,
     VAR_TB,
     VAR_VARS_NB
 };
 
 typedef struct {
     AVExpr *expr;
     double var_values[VAR_VARS_NB];
 } SetPTSContext;
 
 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
 {
     SetPTSContext *setpts = ctx->priv;
     int ret;
 

     if ((ret = av_expr_parse(&setpts->expr, args ? args : "PTS",

                              var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
         av_log(ctx, AV_LOG_ERROR, "Error while parsing expression '%s'\n", args);
         return ret;
     }
 
     setpts->var_values[VAR_N          ] = 0.0;
     setpts->var_values[VAR_PREV_INPTS ] = NAN;
     setpts->var_values[VAR_PREV_OUTPTS] = NAN;
     setpts->var_values[VAR_STARTPTS   ] = NAN;
     return 0;
 }
 
 static int config_input(AVFilterLink *inlink)
 {
     SetPTSContext *setpts = inlink->dst->priv;
 
     setpts->var_values[VAR_TB] = av_q2d(inlink->time_base);
 
     av_log(inlink->src, AV_LOG_INFO, "TB:%f\n", setpts->var_values[VAR_TB]);
     return 0;
 }
 
 #define D2TS(d)  (isnan(d) ? AV_NOPTS_VALUE : (int64_t)(d))
 #define TS2D(ts) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts))
 
 static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *inpicref)
 {
     SetPTSContext *setpts = inlink->dst->priv;
     double d;
     AVFilterBufferRef *outpicref = avfilter_ref_buffer(inpicref, ~0);
 
     if (isnan(setpts->var_values[VAR_STARTPTS]))
         setpts->var_values[VAR_STARTPTS] = TS2D(inpicref->pts);
 
     setpts->var_values[VAR_INTERLACED] = inpicref->video->interlaced;
     setpts->var_values[VAR_PTS       ] = TS2D(inpicref->pts);
     setpts->var_values[VAR_POS       ] = inpicref->pos == -1 ? NAN : inpicref->pos;
 

     d = av_expr_eval(setpts->expr, setpts->var_values, NULL);

     outpicref->pts = D2TS(d);
 
 #ifdef DEBUG
     av_log(inlink->dst, AV_LOG_DEBUG,

            "n:%"PRId64" interlaced:%d pos:%"PRId64" pts:%"PRId64" t:%f -> pts:%"PRId64" t:%f\n",

            (int64_t)setpts->var_values[VAR_N],
            (int)setpts->var_values[VAR_INTERLACED],

            inpicref ->pos,

            inpicref ->pts, inpicref ->pts * av_q2d(inlink->time_base),
            outpicref->pts, outpicref->pts * av_q2d(inlink->time_base));
 #endif
 
     setpts->var_values[VAR_N] += 1.0;
     setpts->var_values[VAR_PREV_INPTS ] = TS2D(inpicref ->pts);
     setpts->var_values[VAR_PREV_OUTPTS] = TS2D(outpicref->pts);
     avfilter_start_frame(inlink->dst->outputs[0], outpicref);
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     SetPTSContext *setpts = ctx->priv;

     av_expr_free(setpts->expr);

     setpts->expr = NULL;
 }
 
 AVFilter avfilter_vf_setpts = {
     .name      = "setpts",
     .description = NULL_IF_CONFIG_SMALL("Set PTS for the output video frame."),
     .init      = init,
     .uninit    = uninit,
 
     .priv_size = sizeof(SetPTSContext),
 

     .inputs    = (const AVFilterPad[]) {{ .name       = "default",

                                     .type             = AVMEDIA_TYPE_VIDEO,
                                     .get_video_buffer = avfilter_null_get_video_buffer,
                                     .config_props     = config_input,
                                     .start_frame      = start_frame, },
                                   { .name = NULL }},

     .outputs   = (const AVFilterPad[]) {{ .name       = "default",

                                     .type             = AVMEDIA_TYPE_VIDEO, },
                                   { .name = NULL}},
 };