ref: 4b0bfe8f7d5cc99e6b803a57c1092e593ee28986
dir: /vp9/encoder/vp9_skin_detection.c/
/* * Copyright (c) 2015 The WebM project authors. All Rights Reserved. * * Use of this source code is governed by a BSD-style license * that can be found in the LICENSE file in the root of the source * tree. An additional intellectual property rights grant can be found * in the file PATENTS. All contributing project authors may * be found in the AUTHORS file in the root of the source tree. */ #include <limits.h> #include <math.h> #include "vp9/common/vp9_blockd.h" #include "vp9/encoder/vp9_encoder.h" #include "vp9/encoder/vp9_skin_detection.h" int 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) { // No skin if block has been zero/small motion for long consecutive time. if (consec_zeromv > 60 && curr_motion_magn == 0) { return 0; } else { int motion = 1; // Take center pixel in block to determine is_skin. const int y_width_shift = (4 << b_width_log2_lookup[bsize]) >> 1; const int y_height_shift = (4 << b_height_log2_lookup[bsize]) >> 1; const int uv_width_shift = y_width_shift >> 1; const int uv_height_shift = y_height_shift >> 1; const uint8_t ysource = y[y_height_shift * stride + y_width_shift]; const uint8_t usource = u[uv_height_shift * strideuv + uv_width_shift]; const uint8_t vsource = v[uv_height_shift * strideuv + uv_width_shift]; if (consec_zeromv > 25 && curr_motion_magn == 0) motion = 0; return vpx_skin_pixel(ysource, usource, vsource, motion); } } void vp9_compute_skin_sb(VP9_COMP *const cpi, BLOCK_SIZE bsize, int mi_row, int mi_col) { int i, j, num_bl; VP9_COMMON *const cm = &cpi->common; const uint8_t *src_y = cpi->Source->y_buffer; const uint8_t *src_u = cpi->Source->u_buffer; const uint8_t *src_v = cpi->Source->v_buffer; const int src_ystride = cpi->Source->y_stride; const int src_uvstride = cpi->Source->uv_stride; const int y_bsize = 4 << b_width_log2_lookup[bsize]; const int uv_bsize = y_bsize >> 1; const int shy = (y_bsize == 8) ? 3 : 4; const int shuv = shy - 1; const int fac = y_bsize / 8; const int y_shift = src_ystride * (mi_row << 3) + (mi_col << 3); const int uv_shift = src_uvstride * (mi_row << 2) + (mi_col << 2); const int mi_row_limit = VPXMIN(mi_row + 8, cm->mi_rows - 2); const int mi_col_limit = VPXMIN(mi_col + 8, cm->mi_cols - 2); src_y += y_shift; src_u += uv_shift; src_v += uv_shift; for (i = mi_row; i < mi_row_limit; i += fac) { num_bl = 0; for (j = mi_col; j < mi_col_limit; j += fac) { int consec_zeromv = 0; int bl_index = i * cm->mi_cols + j; int bl_index1 = bl_index + 1; int bl_index2 = bl_index + cm->mi_cols; int bl_index3 = bl_index2 + 1; // Don't detect skin on the boundary. if (i == 0 || j == 0) continue; if (bsize == BLOCK_8X8) consec_zeromv = cpi->consec_zero_mv[bl_index]; else consec_zeromv = VPXMIN(cpi->consec_zero_mv[bl_index], VPXMIN(cpi->consec_zero_mv[bl_index1], VPXMIN(cpi->consec_zero_mv[bl_index2], cpi->consec_zero_mv[bl_index3]))); cpi->skin_map[bl_index] = vp9_compute_skin_block(src_y, src_u, src_v, src_ystride, src_uvstride, bsize, consec_zeromv, 0); num_bl++; src_y += y_bsize; src_u += uv_bsize; src_v += uv_bsize; } src_y += (src_ystride << shy) - (num_bl << shy); src_u += (src_uvstride << shuv) - (num_bl << shuv); src_v += (src_uvstride << shuv) - (num_bl << shuv); } // Remove isolated skin blocks (none of its neighbors are skin) and isolated // non-skin blocks (all of its neighbors are skin). // Skip 4 corner blocks which have only 3 neighbors to remove isolated skin // blocks. Skip superblock borders to remove isolated non-skin blocks. for (i = mi_row; i < mi_row_limit; i += fac) { for (j = mi_col; j < mi_col_limit; j += fac) { int bl_index = i * cm->mi_cols + j; int num_neighbor = 0; int mi, mj; int non_skin_threshold = 8; // Skip 4 corners. if ((i == mi_row && (j == mi_col || j == mi_col_limit - fac)) || (i == mi_row_limit - fac && (j == mi_col || j == mi_col_limit - fac))) continue; // There are only 5 neighbors for non-skin blocks on the border. if (i == mi_row || i == mi_row_limit - fac || j == mi_col || j == mi_col_limit - fac) non_skin_threshold = 5; for (mi = -fac; mi <= fac; mi += fac) { for (mj = -fac; mj <= fac; mj += fac) { if (i + mi >= mi_row && i + mi < mi_row_limit && j + mj >= mi_col && j + mj < mi_col_limit) { int bl_neighbor_index = (i + mi) * cm->mi_cols + j + mj; if (cpi->skin_map[bl_neighbor_index]) num_neighbor++; } } } if (cpi->skin_map[bl_index] && num_neighbor < 2) cpi->skin_map[bl_index] = 0; if (!cpi->skin_map[bl_index] && num_neighbor == non_skin_threshold) cpi->skin_map[bl_index] = 1; } } } #ifdef OUTPUT_YUV_SKINMAP // For viewing skin map on input source. void vp9_output_skin_map(VP9_COMP *const cpi, FILE *yuv_skinmap_file) { int i, j, mi_row, mi_col, num_bl; VP9_COMMON *const cm = &cpi->common; uint8_t *y; const uint8_t *src_y = cpi->Source->y_buffer; const int src_ystride = cpi->Source->y_stride; const int y_bsize = 16; // Use 8x8 or 16x16. const int shy = (y_bsize == 8) ? 3 : 4; const int fac = y_bsize / 8; YV12_BUFFER_CONFIG skinmap; memset(&skinmap, 0, sizeof(YV12_BUFFER_CONFIG)); if (vpx_alloc_frame_buffer(&skinmap, cm->width, cm->height, cm->subsampling_x, cm->subsampling_y, VP9_ENC_BORDER_IN_PIXELS, cm->byte_alignment)) { vpx_free_frame_buffer(&skinmap); return; } memset(skinmap.buffer_alloc, 128, skinmap.frame_size); y = skinmap.y_buffer; // Loop through blocks and set skin map based on center pixel of block. // Set y to white for skin block, otherwise set to source with gray scale. // Ignore rightmost/bottom boundary blocks. for (mi_row = 0; mi_row < cm->mi_rows - 1; mi_row += fac) { num_bl = 0; for (mi_col = 0; mi_col < cm->mi_cols - 1; mi_col += fac) { const int block_index = mi_row * cm->mi_cols + mi_col; const int is_skin = cpi->skin_map[block_index]; for (i = 0; i < y_bsize; i++) { for (j = 0; j < y_bsize; j++) { y[i * src_ystride + j] = is_skin ? 255 : src_y[i * src_ystride + j]; } } num_bl++; y += y_bsize; src_y += y_bsize; } y += (src_ystride << shy) - (num_bl << shy); src_y += (src_ystride << shy) - (num_bl << shy); } vpx_write_yuv_frame(yuv_skinmap_file, &skinmap); vpx_free_frame_buffer(&skinmap); } #endif