libavfilter/vf_slicify.c

   1 /*
   2  * copyright (c) 2007 Bobby Bingham
   3  *
   4  * This file is part of FFmpeg.
   5  *
   6  * FFmpeg is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * FFmpeg is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with FFmpeg; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 /**
  22  * @file
  23  * video slicing filter
  24  */
  25
  26 #include "avfilter.h"
  27 #include "libavutil/pixdesc.h"
  28
  29 typedef struct {
  30     int h;          ///< output slice height
  31     int vshift;     ///< vertical chroma subsampling shift
  32     uint32_t lcg_state; ///< LCG state used to compute random slice height
  33     int use_random_h;   ///< enable the use of random slice height values
  34 } SliceContext;
  35
  36 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
  37 {
  38     SliceContext *slice = ctx->priv;
  39
  40     slice->h = 16;
  41     if (args) {
  42         if (!strcmp(args, "random")) {
  43             slice->use_random_h = 1;
  44         } else {
  45             sscanf(args, "%d", &slice->h);
  46         }
  47     }
  48     return 0;
  49 }
  50
  51 static int config_props(AVFilterLink *link)
  52 {
  53     SliceContext *slice = link->dst->priv;
  54
  55     slice->vshift = av_pix_fmt_descriptors[link->format].log2_chroma_h;
  56
  57     return 0;
  58 }
  59
  60 static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
  61 {
  62     SliceContext *slice = link->dst->priv;
  63
  64     if (slice->use_random_h) {
  65         slice->lcg_state = slice->lcg_state * 1664525 + 1013904223;
  66         slice->h = 8 + (uint64_t)slice->lcg_state * 25 / UINT32_MAX;
  67     }
  68
  69     /* ensure that slices play nice with chroma subsampling, and enforce
  70      * a reasonable minimum size for the slices */
  71     slice->h = FFMAX(8, slice->h & (-1 << slice->vshift));
  72
  73     av_log(link->dst, AV_LOG_DEBUG, "h:%d\n", slice->h);
  74
  75     avfilter_start_frame(link->dst->outputs[0], picref);
  76 }
  77
  78 static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
  79 {
  80     SliceContext *slice = link->dst->priv;
  81     int y2;
  82
  83     if (slice_dir == 1) {
  84         for (y2 = y; y2 + slice->h <= y + h; y2 += slice->h)
  85             avfilter_draw_slice(link->dst->outputs[0], y2, slice->h, slice_dir);
  86
  87         if (y2 < y + h)
  88             avfilter_draw_slice(link->dst->outputs[0], y2, y + h - y2, slice_dir);
  89     } else if (slice_dir == -1) {
  90         for (y2 = y + h; y2 - slice->h >= y; y2 -= slice->h)
  91             avfilter_draw_slice(link->dst->outputs[0], y2 - slice->h, slice->h, slice_dir);
  92
  93         if (y2 > y)
  94             avfilter_draw_slice(link->dst->outputs[0], y, y2 - y, slice_dir);
  95     }
  96 }
  97
  98 AVFilter avfilter_vf_slicify = {
  99     .name      = "slicify",
 100     .description = "Pass the images of input video on to next video filter as multiple slices.",
 101
 102     .init      = init,
 103
 104     .priv_size = sizeof(SliceContext),
 105
 106     .inputs    = (AVFilterPad[]) {{ .name             = "default",
 107                                     .type             = AVMEDIA_TYPE_VIDEO,
 108                                     .get_video_buffer = avfilter_null_get_video_buffer,
 109                                     .start_frame      = start_frame,
 110                                     .draw_slice       = draw_slice,
 111                                     .config_props     = config_props,
 112                                     .end_frame        = avfilter_null_end_frame, },
 113                                   { .name = NULL}},
 114     .outputs   = (AVFilterPad[]) {{ .name            = "default",
 115                                     .type            = AVMEDIA_TYPE_VIDEO, },
 116                                   { .name = NULL}},
 117 };