/*
  * Copyright (c) 2012 Rudolf Polzer
  * Copyright (c) 2013 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 telecine filter, heavily based from mpv-player:TOOLS/vf_dlopen/telecine.c by
  * Rudolf Polzer.
  */
 
 #include "libavutil/avstring.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
 #include "video.h"
 

 typedef struct TelecineContext {

     const AVClass *class;
     int first_field;
     char *pattern;
     unsigned int pattern_pos;

     int64_t start_time;

 
     AVRational pts;

     AVRational ts_unit;

     int out_cnt;
     int occupied;
 
     int nb_planes;
     int planeheight[4];
     int stride[4];
 
     AVFrame *frame[5];
     AVFrame *temp;
 } TelecineContext;
 
 #define OFFSET(x) offsetof(TelecineContext, x)
 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 
 static const AVOption telecine_options[] = {
     {"first_field", "select first field", OFFSET(first_field), AV_OPT_TYPE_INT,   {.i64=0}, 0, 1, FLAGS, "field"},
         {"top",    "select top field first",                0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, FLAGS, "field"},
         {"t",      "select top field first",                0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, FLAGS, "field"},
         {"bottom", "select bottom field first",             0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, FLAGS, "field"},
         {"b",      "select bottom field first",             0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, FLAGS, "field"},
     {"pattern", "pattern that describe for how many fields a frame is to be displayed", OFFSET(pattern), AV_OPT_TYPE_STRING, {.str="23"}, 0, 0, FLAGS},
     {NULL}
 };
 
 AVFILTER_DEFINE_CLASS(telecine);
 

 static av_cold int init(AVFilterContext *ctx)

 {

     TelecineContext *s = ctx->priv;

     const char *p;
     int max = 0;
 

     if (!strlen(s->pattern)) {

         av_log(ctx, AV_LOG_ERROR, "No pattern provided.\n");
         return AVERROR_INVALIDDATA;
     }
 

     for (p = s->pattern; *p; p++) {

         if (!av_isdigit(*p)) {
             av_log(ctx, AV_LOG_ERROR, "Provided pattern includes non-numeric characters.\n");
             return AVERROR_INVALIDDATA;
         }
 
         max = FFMAX(*p - '0', max);

         s->pts.num += 2;
         s->pts.den += *p - '0';

     }
 

     s->start_time = AV_NOPTS_VALUE;
 

     s->out_cnt = (max + 1) / 2;

     av_log(ctx, AV_LOG_INFO, "Telecine pattern %s yields up to %d frames per frame, pts advance factor: %d/%d\n",

            s->pattern, s->out_cnt, s->pts.num, s->pts.den);

 
     return 0;
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     AVFilterFormats *pix_fmts = NULL;

     int fmt, ret;

     for (fmt = 0; av_pix_fmt_desc_get(fmt); fmt++) {

         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(fmt);

         if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL ||
               desc->flags & AV_PIX_FMT_FLAG_PAL     ||

               desc->flags & AV_PIX_FMT_FLAG_BITSTREAM) &&
             (ret = ff_add_format(&pix_fmts, fmt)) < 0)
             return ret;

     }
 

     return ff_set_common_formats(ctx, pix_fmts);

 }
 
 static int config_input(AVFilterLink *inlink)
 {

     TelecineContext *s = inlink->dst->priv;

     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
     int i, ret;
 

     s->temp = ff_get_video_buffer(inlink, inlink->w, inlink->h);
     if (!s->temp)

         return AVERROR(ENOMEM);

     for (i = 0; i < s->out_cnt; i++) {
         s->frame[i] = ff_get_video_buffer(inlink, inlink->w, inlink->h);
         if (!s->frame[i])

             return AVERROR(ENOMEM);
     }
 

     if ((ret = av_image_fill_linesizes(s->stride, inlink->format, inlink->w)) < 0)

         return ret;
 

     s->planeheight[1] = s->planeheight[2] = AV_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);

     s->planeheight[0] = s->planeheight[3] = inlink->h;

     s->nb_planes = av_pix_fmt_count_planes(inlink->format);

 
     return 0;
 }
 
 static int config_output(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;

     TelecineContext *s = ctx->priv;

     const AVFilterLink *inlink = ctx->inputs[0];
     AVRational fps = inlink->frame_rate;
 
     if (!fps.num || !fps.den) {
         av_log(ctx, AV_LOG_ERROR, "The input needs a constant frame rate; "
                "current rate of %d/%d is invalid\n", fps.num, fps.den);
         return AVERROR(EINVAL);
     }

     fps = av_mul_q(fps, av_inv_q(s->pts));

     av_log(ctx, AV_LOG_VERBOSE, "FPS: %d/%d -> %d/%d\n",
            inlink->frame_rate.num, inlink->frame_rate.den, fps.num, fps.den);
 
     outlink->frame_rate = fps;

     outlink->time_base = av_mul_q(inlink->time_base, s->pts);

     av_log(ctx, AV_LOG_VERBOSE, "TB: %d/%d -> %d/%d\n",
            inlink->time_base.num, inlink->time_base.den, outlink->time_base.num, outlink->time_base.den);

     s->ts_unit = av_inv_q(av_mul_q(fps, outlink->time_base));

 
     return 0;
 }
 
 static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
 {
     AVFilterContext *ctx = inlink->dst;
     AVFilterLink *outlink = ctx->outputs[0];

     TelecineContext *s = ctx->priv;

     int i, len, ret = 0, nout = 0;
 

     if (s->start_time == AV_NOPTS_VALUE)
         s->start_time = inpicref->pts;
 

     len = s->pattern[s->pattern_pos] - '0';

     s->pattern_pos++;
     if (!s->pattern[s->pattern_pos])
         s->pattern_pos = 0;

 
     if (!len) { // do not output any field from this frame
         av_frame_free(&inpicref);
         return 0;
     }
 

     if (s->occupied) {

         av_frame_make_writable(s->frame[nout]);

         for (i = 0; i < s->nb_planes; i++) {

             // fill in the EARLIER field from the buffered pic

             av_image_copy_plane(s->frame[nout]->data[i] + s->frame[nout]->linesize[i] * s->first_field,
                                 s->frame[nout]->linesize[i] * 2,
                                 s->temp->data[i] + s->temp->linesize[i] * s->first_field,
                                 s->temp->linesize[i] * 2,
                                 s->stride[i],
                                 (s->planeheight[i] - s->first_field + 1) / 2);

             // fill in the LATER field from the new pic

             av_image_copy_plane(s->frame[nout]->data[i] + s->frame[nout]->linesize[i] * !s->first_field,
                                 s->frame[nout]->linesize[i] * 2,
                                 inpicref->data[i] + inpicref->linesize[i] * !s->first_field,

                                 inpicref->linesize[i] * 2,

                                 s->stride[i],
                                 (s->planeheight[i] - !s->first_field + 1) / 2);

         }
         nout++;
         len--;

         s->occupied = 0;

     }
 
     while (len >= 2) {
         // output THIS image as-is

         av_frame_make_writable(s->frame[nout]);

         for (i = 0; i < s->nb_planes; i++)
             av_image_copy_plane(s->frame[nout]->data[i], s->frame[nout]->linesize[i],

                                 inpicref->data[i], inpicref->linesize[i],

                                 s->stride[i],
                                 s->planeheight[i]);

         nout++;
         len -= 2;
     }
 
     if (len >= 1) {
         // copy THIS image to the buffer, we need it later

         for (i = 0; i < s->nb_planes; i++)
             av_image_copy_plane(s->temp->data[i], s->temp->linesize[i],

                                 inpicref->data[i], inpicref->linesize[i],

                                 s->stride[i],
                                 s->planeheight[i]);
         s->occupied = 1;

     }
 
     for (i = 0; i < nout; i++) {

         AVFrame *frame = av_frame_clone(s->frame[i]);

 
         if (!frame) {
             av_frame_free(&inpicref);
             return AVERROR(ENOMEM);
         }
 

         av_frame_copy_props(frame, inpicref);

         frame->pts = ((s->start_time == AV_NOPTS_VALUE) ? 0 : s->start_time) +

                      av_rescale(outlink->frame_count_in, s->ts_unit.num,

                                 s->ts_unit.den);

         ret = ff_filter_frame(outlink, frame);
     }
     av_frame_free(&inpicref);
 
     return ret;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {

     TelecineContext *s = ctx->priv;

     int i;
 

     av_frame_free(&s->temp);
     for (i = 0; i < s->out_cnt; i++)
         av_frame_free(&s->frame[i]);

 }
 
 static const AVFilterPad telecine_inputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
         .filter_frame  = filter_frame,
         .config_props  = config_input,
     },
     { NULL }
 };
 
 static const AVFilterPad telecine_outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
         .config_props  = config_output,
     },
     { NULL }
 };
 

 AVFilter ff_vf_telecine = {

     .name          = "telecine",
     .description   = NULL_IF_CONFIG_SMALL("Apply a telecine pattern."),
     .priv_size     = sizeof(TelecineContext),
     .priv_class    = &telecine_class,
     .init          = init,
     .uninit        = uninit,
     .query_formats = query_formats,
     .inputs        = telecine_inputs,
     .outputs       = telecine_outputs,
 };