/*

  * Copyright (c) 2003 Michael Zucchi <notzed@ximian.com>
  * Copyright (c) 2010 Baptiste Coudurier
  * Copyright (c) 2011 Stefano Sabatini
  * Copyright (c) 2013 Vittorio Giovara <vittorio.giovara@gmail.com>

  *

  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 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 General Public License for more details.
  *
  * You should have received a copy of the GNU 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
  * progressive to interlaced content filter, inspired by heavy debugging of tinterlace filter
  */
 
 #include "libavutil/common.h"
 #include "libavutil/opt.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/avassert.h"
 
 #include "formats.h"
 #include "avfilter.h"

 #include "interlace.h"

 #include "internal.h"
 #include "video.h"
 
 #define OFFSET(x) offsetof(InterlaceContext, x)

 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM

 static const AVOption interlace_options[] = {

     { "scan", "scanning mode", OFFSET(scan),

         AV_OPT_TYPE_INT,   {.i64 = MODE_TFF }, 0, 1, .flags = FLAGS, .unit = "scan" },

     { "tff", "top field first", 0,

         AV_OPT_TYPE_CONST, {.i64 = MODE_TFF }, INT_MIN, INT_MAX, .flags = FLAGS, .unit = "scan" },

     { "bff", "bottom field first", 0,

         AV_OPT_TYPE_CONST, {.i64 = MODE_BFF }, INT_MIN, INT_MAX, .flags = FLAGS, .unit = "scan" },

     { "lowpass", "set vertical low-pass filter", OFFSET(lowpass),

         AV_OPT_TYPE_BOOL,  {.i64 = 1 },        0, 1, .flags = FLAGS },

     { NULL }
 };
 

 AVFILTER_DEFINE_CLASS(interlace);

 static void lowpass_line_c(uint8_t *dstp, ptrdiff_t linesize,
                            const uint8_t *srcp,
                            const uint8_t *srcp_above,
                            const uint8_t *srcp_below)
 {
     int i;
     for (i = 0; i < linesize; i++) {
         // this calculation is an integer representation of
         // '0.5 * current + 0.25 * above + 0.25 * below'
         // '1 +' is for rounding.
         dstp[i] = (1 + srcp[i] + srcp[i] + srcp_above[i] + srcp_below[i]) >> 2;
     }
 }

 
 static const enum AVPixelFormat formats_supported[] = {
     AV_PIX_FMT_YUV420P,  AV_PIX_FMT_YUV422P,  AV_PIX_FMT_YUV444P,
     AV_PIX_FMT_YUV444P,  AV_PIX_FMT_YUV410P,  AV_PIX_FMT_YUVA420P,
     AV_PIX_FMT_GRAY8,    AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P,
     AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_NONE
 };
 
 static int query_formats(AVFilterContext *ctx)
 {

     AVFilterFormats *fmts_list = ff_make_format_list(formats_supported);
     if (!fmts_list)
         return AVERROR(ENOMEM);
     return ff_set_common_formats(ctx, fmts_list);

 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     InterlaceContext *s = ctx->priv;
 
     av_frame_free(&s->cur);
     av_frame_free(&s->next);
 }
 
 static int config_out_props(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     AVFilterLink *inlink = outlink->src->inputs[0];
     InterlaceContext *s = ctx->priv;
 
     if (inlink->h < 2) {
         av_log(ctx, AV_LOG_ERROR, "input video height is too small\n");
         return AVERROR_INVALIDDATA;
     }

 
     if (!s->lowpass)

         av_log(ctx, AV_LOG_WARNING, "Lowpass filter is disabled, "

                "the resulting video will be aliased rather than interlaced.\n");
 

     // same input size
     outlink->w = inlink->w;
     outlink->h = inlink->h;
     outlink->time_base = inlink->time_base;

     outlink->frame_rate = inlink->frame_rate;

     // half framerate

     outlink->time_base.num *= 2;

     outlink->frame_rate.den *= 2;

 
     if (s->lowpass) {
         s->lowpass_line = lowpass_line_c;
         if (ARCH_X86)
             ff_interlace_init_x86(s);
     }
 

     av_log(ctx, AV_LOG_VERBOSE, "%s interlacing %s lowpass filter\n",
            s->scan == MODE_TFF ? "tff" : "bff", (s->lowpass) ? "with" : "without");

 
     return 0;
 }
 

 static void copy_picture_field(InterlaceContext *s,
                                AVFrame *src_frame, AVFrame *dst_frame,

                                AVFilterLink *inlink, enum FieldType field_type,
                                int lowpass)

 {
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);

     int hsub = desc->log2_chroma_w;

     int vsub = desc->log2_chroma_h;

     int plane, j;

 
     for (plane = 0; plane < desc->nb_components; plane++) {

         int cols  = (plane == 1 || plane == 2) ? -(-inlink->w) >> hsub : inlink->w;

         int lines = (plane == 1 || plane == 2) ? AV_CEIL_RSHIFT(inlink->h, vsub) : inlink->h;

         uint8_t *dstp = dst_frame->data[plane];
         const uint8_t *srcp = src_frame->data[plane];
 

         av_assert0(cols >= 0 || lines >= 0);

         lines = (lines + (field_type == FIELD_UPPER)) / 2;

         if (field_type == FIELD_LOWER) {

             srcp += src_frame->linesize[plane];
             dstp += dst_frame->linesize[plane];

         }

         if (lowpass) {
             int srcp_linesize = src_frame->linesize[plane] * 2;
             int dstp_linesize = dst_frame->linesize[plane] * 2;
             for (j = lines; j > 0; j--) {
                 const uint8_t *srcp_above = srcp - src_frame->linesize[plane];
                 const uint8_t *srcp_below = srcp + src_frame->linesize[plane];
                 if (j == lines)
                     srcp_above = srcp; // there is no line above
                 if (j == 1)
                     srcp_below = srcp; // there is no line below

                 s->lowpass_line(dstp, cols, srcp, srcp_above, srcp_below);

                 dstp += dstp_linesize;
                 srcp += srcp_linesize;

             }

         } else {
             av_image_copy_plane(dstp, dst_frame->linesize[plane] * 2,
                                 srcp, src_frame->linesize[plane] * 2,

                                 cols, lines);

         }
     }
 }
 
 static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
 {
     AVFilterContext *ctx = inlink->dst;
     AVFilterLink *outlink = ctx->outputs[0];
     InterlaceContext *s = ctx->priv;
     AVFrame *out;
     int tff, ret;
 
     av_frame_free(&s->cur);
     s->cur  = s->next;
     s->next = buf;
 
     /* we need at least two frames */
     if (!s->cur || !s->next)
         return 0;
 

     if (s->cur->interlaced_frame) {
         av_log(ctx, AV_LOG_WARNING,
                "video is already interlaced, adjusting framerate only\n");
         out = av_frame_clone(s->cur);

         if (!out)
             return AVERROR(ENOMEM);

         out->pts /= 2;  // adjust pts to new framerate
         ret = ff_filter_frame(outlink, out);
         return ret;
     }
 

     tff = (s->scan == MODE_TFF);
     out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
     if (!out)
         return AVERROR(ENOMEM);
 
     av_frame_copy_props(out, s->cur);
     out->interlaced_frame = 1;
     out->top_field_first  = tff;

     out->pts             /= 2;  // adjust pts to new framerate

 
     /* copy upper/lower field from cur */

     copy_picture_field(s, s->cur, out, inlink, tff ? FIELD_UPPER : FIELD_LOWER, s->lowpass);

     av_frame_free(&s->cur);
 
     /* copy lower/upper field from next */

     copy_picture_field(s, s->next, out, inlink, tff ? FIELD_LOWER : FIELD_UPPER, s->lowpass);

     av_frame_free(&s->next);
 
     ret = ff_filter_frame(outlink, out);
 
     return ret;
 }
 
 static const AVFilterPad inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame,
     },
     { NULL }
 };
 
 static const AVFilterPad outputs[] = {
     {

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

     },
     { NULL }
 };
 

 AVFilter ff_vf_interlace = {

     .name          = "interlace",
     .description   = NULL_IF_CONFIG_SMALL("Convert progressive video into interlaced."),
     .uninit        = uninit,

     .priv_class    = &interlace_class,

     .priv_size     = sizeof(InterlaceContext),
     .query_formats = query_formats,
     .inputs        = inputs,
     .outputs       = outputs,
 };