1/*
2 *  Copyright (c) 2015 The WebM project authors. All Rights Reserved.
3 *
4 *  Use of this source code is governed by a BSD-style license
5 *  that can be found in the LICENSE file in the root of the source
6 *  tree. An additional intellectual property rights grant can be found
7 *  in the file PATENTS.  All contributing project authors may
8 *  be found in the AUTHORS file in the root of the source tree.
9 */
10
11#include <limits.h>
12#include <math.h>
13
14#include "vp9/common/vp9_blockd.h"
15#include "vp9/encoder/vp9_encoder.h"
16#include "vp9/encoder/vp9_skin_detection.h"
17
18int vp9_compute_skin_block(const uint8_t *y, const uint8_t *u, const uint8_t *v,
19                           int stride, int strideuv, int bsize,
20                           int consec_zeromv, int curr_motion_magn) {
21  // No skin if block has been zero/small motion for long consecutive time.
22  if (consec_zeromv > 60 && curr_motion_magn == 0) {
23    return 0;
24  } else {
25    int motion = 1;
26    // Take center pixel in block to determine is_skin.
27    const int y_width_shift = (4 << b_width_log2_lookup[bsize]) >> 1;
28    const int y_height_shift = (4 << b_height_log2_lookup[bsize]) >> 1;
29    const int uv_width_shift = y_width_shift >> 1;
30    const int uv_height_shift = y_height_shift >> 1;
31    const uint8_t ysource = y[y_height_shift * stride + y_width_shift];
32    const uint8_t usource = u[uv_height_shift * strideuv + uv_width_shift];
33    const uint8_t vsource = v[uv_height_shift * strideuv + uv_width_shift];
34
35    if (consec_zeromv > 25 && curr_motion_magn == 0) motion = 0;
36    return vpx_skin_pixel(ysource, usource, vsource, motion);
37  }
38}
39
40void vp9_compute_skin_sb(VP9_COMP *const cpi, BLOCK_SIZE bsize, int mi_row,
41                         int mi_col) {
42  int i, j, num_bl;
43  VP9_COMMON *const cm = &cpi->common;
44  const uint8_t *src_y = cpi->Source->y_buffer;
45  const uint8_t *src_u = cpi->Source->u_buffer;
46  const uint8_t *src_v = cpi->Source->v_buffer;
47  const int src_ystride = cpi->Source->y_stride;
48  const int src_uvstride = cpi->Source->uv_stride;
49  const int y_bsize = 4 << b_width_log2_lookup[bsize];
50  const int uv_bsize = y_bsize >> 1;
51  const int shy = (y_bsize == 8) ? 3 : 4;
52  const int shuv = shy - 1;
53  const int fac = y_bsize / 8;
54  const int y_shift = src_ystride * (mi_row << 3) + (mi_col << 3);
55  const int uv_shift = src_uvstride * (mi_row << 2) + (mi_col << 2);
56  const int mi_row_limit = VPXMIN(mi_row + 8, cm->mi_rows - 2);
57  const int mi_col_limit = VPXMIN(mi_col + 8, cm->mi_cols - 2);
58  src_y += y_shift;
59  src_u += uv_shift;
60  src_v += uv_shift;
61
62  for (i = mi_row; i < mi_row_limit; i += fac) {
63    num_bl = 0;
64    for (j = mi_col; j < mi_col_limit; j += fac) {
65      int consec_zeromv = 0;
66      int bl_index = i * cm->mi_cols + j;
67      int bl_index1 = bl_index + 1;
68      int bl_index2 = bl_index + cm->mi_cols;
69      int bl_index3 = bl_index2 + 1;
70      // Don't detect skin on the boundary.
71      if (i == 0 || j == 0) continue;
72      if (bsize == BLOCK_8X8)
73        consec_zeromv = cpi->consec_zero_mv[bl_index];
74      else
75        consec_zeromv = VPXMIN(cpi->consec_zero_mv[bl_index],
76                               VPXMIN(cpi->consec_zero_mv[bl_index1],
77                                      VPXMIN(cpi->consec_zero_mv[bl_index2],
78                                             cpi->consec_zero_mv[bl_index3])));
79      cpi->skin_map[bl_index] =
80          vp9_compute_skin_block(src_y, src_u, src_v, src_ystride, src_uvstride,
81                                 bsize, consec_zeromv, 0);
82      num_bl++;
83      src_y += y_bsize;
84      src_u += uv_bsize;
85      src_v += uv_bsize;
86    }
87    src_y += (src_ystride << shy) - (num_bl << shy);
88    src_u += (src_uvstride << shuv) - (num_bl << shuv);
89    src_v += (src_uvstride << shuv) - (num_bl << shuv);
90  }
91
92  // Remove isolated skin blocks (none of its neighbors are skin) and isolated
93  // non-skin blocks (all of its neighbors are skin).
94  // Skip 4 corner blocks which have only 3 neighbors to remove isolated skin
95  // blocks. Skip superblock borders to remove isolated non-skin blocks.
96  for (i = mi_row; i < mi_row_limit; i += fac) {
97    for (j = mi_col; j < mi_col_limit; j += fac) {
98      int bl_index = i * cm->mi_cols + j;
99      int num_neighbor = 0;
100      int mi, mj;
101      int non_skin_threshold = 8;
102      // Skip 4 corners.
103      if ((i == mi_row && (j == mi_col || j == mi_col_limit - fac)) ||
104          (i == mi_row_limit - fac && (j == mi_col || j == mi_col_limit - fac)))
105        continue;
106      // There are only 5 neighbors for non-skin blocks on the border.
107      if (i == mi_row || i == mi_row_limit - fac || j == mi_col ||
108          j == mi_col_limit - fac)
109        non_skin_threshold = 5;
110
111      for (mi = -fac; mi <= fac; mi += fac) {
112        for (mj = -fac; mj <= fac; mj += fac) {
113          if (i + mi >= mi_row && i + mi < mi_row_limit && j + mj >= mi_col &&
114              j + mj < mi_col_limit) {
115            int bl_neighbor_index = (i + mi) * cm->mi_cols + j + mj;
116            if (cpi->skin_map[bl_neighbor_index]) num_neighbor++;
117          }
118        }
119      }
120
121      if (cpi->skin_map[bl_index] && num_neighbor < 2)
122        cpi->skin_map[bl_index] = 0;
123      if (!cpi->skin_map[bl_index] && num_neighbor == non_skin_threshold)
124        cpi->skin_map[bl_index] = 1;
125    }
126  }
127}
128
129#ifdef OUTPUT_YUV_SKINMAP
130// For viewing skin map on input source.
131void vp9_output_skin_map(VP9_COMP *const cpi, FILE *yuv_skinmap_file) {
132  int i, j, mi_row, mi_col, num_bl;
133  VP9_COMMON *const cm = &cpi->common;
134  uint8_t *y;
135  const uint8_t *src_y = cpi->Source->y_buffer;
136  const int src_ystride = cpi->Source->y_stride;
137  const int y_bsize = 16;  // Use 8x8 or 16x16.
138  const int shy = (y_bsize == 8) ? 3 : 4;
139  const int fac = y_bsize / 8;
140
141  YV12_BUFFER_CONFIG skinmap;
142  memset(&skinmap, 0, sizeof(YV12_BUFFER_CONFIG));
143  if (vpx_alloc_frame_buffer(&skinmap, cm->width, cm->height, cm->subsampling_x,
144                             cm->subsampling_y, VP9_ENC_BORDER_IN_PIXELS,
145                             cm->byte_alignment)) {
146    vpx_free_frame_buffer(&skinmap);
147    return;
148  }
149  memset(skinmap.buffer_alloc, 128, skinmap.frame_size);
150  y = skinmap.y_buffer;
151  // Loop through blocks and set skin map based on center pixel of block.
152  // Set y to white for skin block, otherwise set to source with gray scale.
153  // Ignore rightmost/bottom boundary blocks.
154  for (mi_row = 0; mi_row < cm->mi_rows - 1; mi_row += fac) {
155    num_bl = 0;
156    for (mi_col = 0; mi_col < cm->mi_cols - 1; mi_col += fac) {
157      const int block_index = mi_row * cm->mi_cols + mi_col;
158      const int is_skin = cpi->skin_map[block_index];
159      for (i = 0; i < y_bsize; i++) {
160        for (j = 0; j < y_bsize; j++) {
161          y[i * src_ystride + j] = is_skin ? 255 : src_y[i * src_ystride + j];
162        }
163      }
164      num_bl++;
165      y += y_bsize;
166      src_y += y_bsize;
167    }
168    y += (src_ystride << shy) - (num_bl << shy);
169    src_y += (src_ystride << shy) - (num_bl << shy);
170  }
171  vpx_write_yuv_frame(yuv_skinmap_file, &skinmap);
172  vpx_free_frame_buffer(&skinmap);
173}
174#endif
175