/*

  * Copyright (c) 2010 Stefano Sabatini

  *
  * 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
  * Set timebase for the output link.
  */
 
 #include "libavutil/avstring.h"
 #include "libavutil/eval.h"
 #include "libavutil/rational.h"
 #include "avfilter.h"
 #include "internal.h"
 
 static const char *var_names[] = {
     "E",
     "PHI",
     "PI",
     "AVTB",   /* default timebase 1/AV_TIME_BASE */
     "intb",   /* input timebase */
     NULL
 };
 
 enum var_name {
     VAR_E,
     VAR_PHI,
     VAR_PI,
     VAR_AVTB,
     VAR_INTB,
     VAR_VARS_NB
 };
 
 typedef struct {
     char tb_expr[256];
     double var_values[VAR_VARS_NB];
 } SetTBContext;
 
 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
 {
     SetTBContext *settb = ctx->priv;
     av_strlcpy(settb->tb_expr, "intb", sizeof(settb->tb_expr));
 
     if (args)
         sscanf(args, "%255[^:]", settb->tb_expr);
 
     return 0;
 }
 
 static int config_output_props(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     SetTBContext *settb = ctx->priv;
     AVFilterLink *inlink = ctx->inputs[0];
     AVRational time_base;
     int ret;
     double res;
 
     settb->var_values[VAR_E]    = M_E;
     settb->var_values[VAR_PHI]  = M_PHI;
     settb->var_values[VAR_PI]   = M_PI;
     settb->var_values[VAR_AVTB] = av_q2d(AV_TIME_BASE_Q);
     settb->var_values[VAR_INTB] = av_q2d(inlink->time_base);
 
     outlink->w = inlink->w;
     outlink->h = inlink->h;
 

     if ((ret = av_expr_parse_and_eval(&res, settb->tb_expr, var_names, settb->var_values,

                                       NULL, NULL, NULL, NULL, NULL, 0, NULL)) < 0) {
         av_log(ctx, AV_LOG_ERROR, "Invalid expression '%s' for timebase.\n", settb->tb_expr);
         return ret;
     }
     time_base = av_d2q(res, INT_MAX);
     if (time_base.num <= 0 || time_base.den <= 0) {
         av_log(ctx, AV_LOG_ERROR,
                "Invalid non-positive values for the timebase num:%d or den:%d.\n",
                time_base.num, time_base.den);
         return AVERROR(EINVAL);
     }
 
     outlink->time_base = time_base;
     av_log(outlink->src, AV_LOG_INFO, "tb:%d/%d -> tb:%d/%d\n",
            inlink ->time_base.num, inlink ->time_base.den,
            outlink->time_base.num, outlink->time_base.den);
 
     return 0;
 }
 
 static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
 {
     AVFilterContext *ctx = inlink->dst;
     AVFilterLink *outlink = ctx->outputs[0];
     AVFilterBufferRef *picref2 = picref;
 
     if (av_cmp_q(inlink->time_base, outlink->time_base)) {
         picref2 = avfilter_ref_buffer(picref, ~0);
         picref2->pts = av_rescale_q(picref->pts, inlink->time_base, outlink->time_base);
         av_log(ctx, AV_LOG_DEBUG, "tb:%d/%d pts:%"PRId64" -> tb:%d/%d pts:%"PRId64"\n",
                inlink ->time_base.num, inlink ->time_base.den, picref ->pts,
                outlink->time_base.num, outlink->time_base.den, picref2->pts);
         avfilter_unref_buffer(picref);
     }
 
     avfilter_start_frame(outlink, picref2);
 }
 
 AVFilter avfilter_vf_settb = {
     .name      = "settb",
     .description = NULL_IF_CONFIG_SMALL("Set timebase for the output link."),
     .init      = init,
 
     .priv_size = sizeof(SetTBContext),
 
     .inputs    = (AVFilterPad[]) {{ .name             = "default",
                                     .type             = AVMEDIA_TYPE_VIDEO,
                                     .get_video_buffer = avfilter_null_get_video_buffer,
                                     .start_frame      = start_frame,
                                     .end_frame        = avfilter_null_end_frame },
                                   { .name = NULL }},
 
     .outputs   = (AVFilterPad[]) {{ .name            = "default",
                                     .type            = AVMEDIA_TYPE_VIDEO,
                                     .config_props    = config_output_props, },
                                   { .name = NULL}},
 };