/*

  * Copyright (c) 2007 Bobby Bingham

  *
  * 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 slicing filter
  */
 
 #include "avfilter.h"

 #include "video.h"

 #include "libavutil/pixdesc.h"

 
 typedef struct {
     int h;          ///< output slice height
     int vshift;     ///< vertical chroma subsampling shift

     uint32_t lcg_state; ///< LCG state used to compute random slice height
     int use_random_h;   ///< enable the use of random slice height values

 } SliceContext;
 
 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
 {
     SliceContext *slice = ctx->priv;
 
     slice->h = 16;

     if (args) {
         if (!strcmp(args, "random")) {
             slice->use_random_h = 1;
         } else {
             sscanf(args, "%d", &slice->h);
         }
     }

     return 0;
 }
 
 static int config_props(AVFilterLink *link)
 {
     SliceContext *slice = link->dst->priv;
 

     slice->vshift = av_pix_fmt_descriptors[link->format].log2_chroma_h;

 
     return 0;
 }
 

 static void start_frame(AVFilterLink *link, AVFilterBufferRef *picref)

 {

     SliceContext *slice = link->dst->priv;
 
     if (slice->use_random_h) {
         slice->lcg_state = slice->lcg_state * 1664525 + 1013904223;
         slice->h = 8 + (uint64_t)slice->lcg_state * 25 / UINT32_MAX;
     }
 
     /* ensure that slices play nice with chroma subsampling, and enforce
      * a reasonable minimum size for the slices */
     slice->h = FFMAX(8, slice->h & (-1 << slice->vshift));
 
     av_log(link->dst, AV_LOG_DEBUG, "h:%d\n", slice->h);
 

     avfilter_start_frame(link->dst->outputs[0], picref);
 }
 

 static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)

 {
     SliceContext *slice = link->dst->priv;
     int y2;
 

     if (slice_dir == 1) {

         for (y2 = y; y2 + slice->h <= y + h; y2 += slice->h)
             avfilter_draw_slice(link->dst->outputs[0], y2, slice->h, slice_dir);

         if (y2 < y + h)
             avfilter_draw_slice(link->dst->outputs[0], y2, y + h - y2, slice_dir);

     } else if (slice_dir == -1) {
         for (y2 = y + h; y2 - slice->h >= y; y2 -= slice->h)
             avfilter_draw_slice(link->dst->outputs[0], y2 - slice->h, slice->h, slice_dir);
 
         if (y2 > y)
             avfilter_draw_slice(link->dst->outputs[0], y, y2 - y, slice_dir);
     }

 }
 
 AVFilter avfilter_vf_slicify = {
     .name      = "slicify",

     .description = NULL_IF_CONFIG_SMALL("Pass the images of input video on to next video filter as multiple slices."),

 
     .init      = init,
 
     .priv_size = sizeof(SliceContext),
 

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

                                     .type             = AVMEDIA_TYPE_VIDEO,

                                     .get_video_buffer = ff_null_get_video_buffer,

                                     .start_frame      = start_frame,
                                     .draw_slice       = draw_slice,
                                     .config_props     = config_props,

                                     .end_frame        = ff_null_end_frame, },

                                   { .name = NULL}},

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

                                     .type            = AVMEDIA_TYPE_VIDEO, },

                                   { .name = NULL}},
 };