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 
vp9_compute_skin_block(const uint8_t * y,const uint8_t * u,const uint8_t * v,int stride,int strideuv,int bsize,int consec_zeromv,int curr_motion_magn)18 int 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 
vp9_compute_skin_sb(VP9_COMP * const cpi,BLOCK_SIZE bsize,int mi_row,int mi_col)40 void 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.
vp9_output_skin_map(VP9_COMP * const cpi,FILE * yuv_skinmap_file)131 void 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