src/third_party/libvpx/vp9/encoder/vp9_skin_detection.c - cobalt - Git at Google

 /*
  *  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
	/*
	* 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