The Tor Browser: media/libvpx/vp8/decoder/error_concealment.c@ac0c01689b40 (annotated)

media/libvpx/vp8/decoder/error_concealment.c@ac0c01689b40 (annotated)

media/libvpx/vp8/decoder/error_concealment.c

Thu, 15 Jan 2015 15:59:08 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 15 Jan 2015 15:59:08 +0100
branch: TOR_BUG_9701
changeset 10: ac0c01689b40
permissions: -rw-r--r--

Implement a real Private Browsing Mode condition by changing the API/ABI;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /*
  *  Copyright (c) 2011 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 <assert.h>
 #include "error_concealment.h"
 #include "onyxd_int.h"
 #include "decodemv.h"
 #include "vpx_mem/vpx_mem.h"
 #include "vp8/common/findnearmv.h"
 #define MIN(x,y) (((x)<(y))?(x):(y))
 #define MAX(x,y) (((x)>(y))?(x):(y))
 #define FLOOR(x,q) ((x) & -(1 << (q)))
 #define NUM_NEIGHBORS 20
 typedef struct ec_position
 {
     int row;
     int col;
 } EC_POS;
 /*
  * Regenerate the table in Matlab with:
  * x = meshgrid((1:4), (1:4));
  * y = meshgrid((1:4), (1:4))';
  * W = round((1./(sqrt(x.^2 + y.^2))*2^7));
  * W(1,1) = 0;
  */
 static const int weights_q7[5][5] = {
        {  0,   128,    64,    43,    32 },
        {128,    91,    57,    40,    31 },
        { 64,    57,    45,    36,    29 },
        { 43,    40,    36,    30,    26 },
        { 32,    31,    29,    26,    23 }
 };
 int vp8_alloc_overlap_lists(VP8D_COMP *pbi)
 {
     if (pbi->overlaps != NULL)
     {
         vpx_free(pbi->overlaps);
         pbi->overlaps = NULL;
     }
     pbi->overlaps = vpx_calloc(pbi->common.mb_rows * pbi->common.mb_cols,
                                sizeof(MB_OVERLAP));
     if (pbi->overlaps == NULL)
         return -1;
     return 0;
 }
 void vp8_de_alloc_overlap_lists(VP8D_COMP *pbi)
 {
     vpx_free(pbi->overlaps);
     pbi->overlaps = NULL;
 }
 /* Inserts a new overlap area value to the list of overlaps of a block */
 static void assign_overlap(OVERLAP_NODE* overlaps,
                            union b_mode_info *bmi,
                            int overlap)
 {
     int i;
     if (overlap <= 0)
         return;
     /* Find and assign to the next empty overlap node in the list of overlaps.
      * Empty is defined as bmi == NULL */
     for (i = 0; i < MAX_OVERLAPS; i++)
     {
         if (overlaps[i].bmi == NULL)
         {
             overlaps[i].bmi = bmi;
             overlaps[i].overlap = overlap;
             break;
         }
     }
 }
 /* Calculates the overlap area between two 4x4 squares, where the first
  * square has its upper-left corner at (b1_row, b1_col) and the second
  * square has its upper-left corner at (b2_row, b2_col). Doesn't
  * properly handle squares which do not overlap.
  */
 static int block_overlap(int b1_row, int b1_col, int b2_row, int b2_col)
 {
     const int int_top = MAX(b1_row, b2_row); // top
     const int int_left = MAX(b1_col, b2_col); // left
     /* Since each block is 4x4 pixels, adding 4 (Q3) to the left/top edge
      * gives us the right/bottom edge.
      */
     const int int_right = MIN(b1_col + (4<<3), b2_col + (4<<3)); // right
     const int int_bottom = MIN(b1_row + (4<<3), b2_row + (4<<3)); // bottom
     return (int_bottom - int_top) * (int_right - int_left);
 }
 /* Calculates the overlap area for all blocks in a macroblock at position
  * (mb_row, mb_col) in macroblocks, which are being overlapped by a given
  * overlapping block at position (new_row, new_col) (in pixels, Q3). The
  * first block being overlapped in the macroblock has position (first_blk_row,
  * first_blk_col) in blocks relative the upper-left corner of the image.
  */
 static void calculate_overlaps_mb(B_OVERLAP *b_overlaps, union b_mode_info *bmi,
                                   int new_row, int new_col,
                                   int mb_row, int mb_col,
                                   int first_blk_row, int first_blk_col)
 {
     /* Find the blocks within this MB (defined by mb_row, mb_col) which are
      * overlapped by bmi and calculate and assign overlap for each of those
      * blocks. */
     /* Block coordinates relative the upper-left block */
     const int rel_ol_blk_row = first_blk_row - mb_row * 4;
     const int rel_ol_blk_col = first_blk_col - mb_col * 4;
     /* If the block partly overlaps any previous MB, these coordinates
      * can be < 0. We don't want to access blocks in previous MBs.
      */
     const int blk_idx = MAX(rel_ol_blk_row,0) * 4 + MAX(rel_ol_blk_col,0);
     /* Upper left overlapping block */
     B_OVERLAP *b_ol_ul = &(b_overlaps[blk_idx]);
     /* Calculate and assign overlaps for all blocks in this MB
      * which the motion compensated block overlaps
      */
     /* Avoid calculating overlaps for blocks in later MBs */
     int end_row = MIN(4 + mb_row * 4 - first_blk_row, 2);
     int end_col = MIN(4 + mb_col * 4 - first_blk_col, 2);
     int row, col;
     /* Check if new_row and new_col are evenly divisible by 4 (Q3),
      * and if so we shouldn't check neighboring blocks
      */
     if (new_row >= 0 && (new_row & 0x1F) == 0)
         end_row = 1;
     if (new_col >= 0 && (new_col & 0x1F) == 0)
         end_col = 1;
     /* Check if the overlapping block partly overlaps a previous MB
      * and if so, we're overlapping fewer blocks in this MB.
      */
     if (new_row < (mb_row*16)<<3)
         end_row = 1;
     if (new_col < (mb_col*16)<<3)
         end_col = 1;
     for (row = 0; row < end_row; ++row)
     {
         for (col = 0; col < end_col; ++col)
         {
             /* input in Q3, result in Q6 */
             const int overlap = block_overlap(new_row, new_col,
                                                   (((first_blk_row + row) *
 ) << 3),
                                                   (((first_blk_col + col) *
 ) << 3));
             assign_overlap(b_ol_ul[row * 4 + col].overlaps, bmi, overlap);
         }
     }
 }
 void vp8_calculate_overlaps(MB_OVERLAP *overlap_ul,
                             int mb_rows, int mb_cols,
                             union b_mode_info *bmi,
                             int b_row, int b_col)
 {
     MB_OVERLAP *mb_overlap;
     int row, col, rel_row, rel_col;
     int new_row, new_col;
     int end_row, end_col;
     int overlap_b_row, overlap_b_col;
     int overlap_mb_row, overlap_mb_col;
     /* mb subpixel position */
     row = (4 * b_row) << 3; /* Q3 */
     col = (4 * b_col) << 3; /* Q3 */
     /* reverse compensate for motion */
     new_row = row - bmi->mv.as_mv.row;
     new_col = col - bmi->mv.as_mv.col;
     if (new_row >= ((16*mb_rows) << 3) || new_col >= ((16*mb_cols) << 3))
     {
         /* the new block ended up outside the frame */
         return;
     }
     if (new_row <= (-4 << 3) || new_col <= (-4 << 3))
     {
         /* outside the frame */
         return;
     }
     /* overlapping block's position in blocks */
     overlap_b_row = FLOOR(new_row / 4, 3) >> 3;
     overlap_b_col = FLOOR(new_col / 4, 3) >> 3;
     /* overlapping block's MB position in MBs
      * operations are done in Q3
      */
     overlap_mb_row = FLOOR((overlap_b_row << 3) / 4, 3) >> 3;
     overlap_mb_col = FLOOR((overlap_b_col << 3) / 4, 3) >> 3;
     end_row = MIN(mb_rows - overlap_mb_row, 2);
     end_col = MIN(mb_cols - overlap_mb_col, 2);
     /* Don't calculate overlap for MBs we don't overlap */
     /* Check if the new block row starts at the last block row of the MB */
     if (abs(new_row - ((16*overlap_mb_row) << 3)) < ((3*4) << 3))
         end_row = 1;
     /* Check if the new block col starts at the last block col of the MB */
     if (abs(new_col - ((16*overlap_mb_col) << 3)) < ((3*4) << 3))
         end_col = 1;
     /* find the MB(s) this block is overlapping */
     for (rel_row = 0; rel_row < end_row; ++rel_row)
     {
         for (rel_col = 0; rel_col < end_col; ++rel_col)
         {
             if (overlap_mb_row + rel_row < 0 ||
                 overlap_mb_col + rel_col < 0)
                 continue;
             mb_overlap = overlap_ul + (overlap_mb_row + rel_row) * mb_cols +
                  overlap_mb_col + rel_col;
             calculate_overlaps_mb(mb_overlap->overlaps, bmi,
                                   new_row, new_col,
                                   overlap_mb_row + rel_row,
                                   overlap_mb_col + rel_col,
                                   overlap_b_row + rel_row,
                                   overlap_b_col + rel_col);
         }
     }
 }
 /* Estimates a motion vector given the overlapping blocks' motion vectors.
  * Filters out all overlapping blocks which do not refer to the correct
  * reference frame type.
  */
 static void estimate_mv(const OVERLAP_NODE *overlaps, union b_mode_info *bmi)
 {
     int i;
     int overlap_sum = 0;
     int row_acc = 0;
     int col_acc = 0;
     bmi->mv.as_int = 0;
     for (i=0; i < MAX_OVERLAPS; ++i)
     {
         if (overlaps[i].bmi == NULL)
             break;
         col_acc += overlaps[i].overlap * overlaps[i].bmi->mv.as_mv.col;
         row_acc += overlaps[i].overlap * overlaps[i].bmi->mv.as_mv.row;
         overlap_sum += overlaps[i].overlap;
     }
     if (overlap_sum > 0)
     {
         /* Q9 / Q6 = Q3 */
         bmi->mv.as_mv.col = col_acc / overlap_sum;
         bmi->mv.as_mv.row = row_acc / overlap_sum;
     }
     else
     {
         bmi->mv.as_mv.col = 0;
         bmi->mv.as_mv.row = 0;
     }
 }
 /* Estimates all motion vectors for a macroblock given the lists of
  * overlaps for each block. Decides whether or not the MVs must be clamped.
  */
 static void estimate_mb_mvs(const B_OVERLAP *block_overlaps,
                             MODE_INFO *mi,
                             int mb_to_left_edge,
                             int mb_to_right_edge,
                             int mb_to_top_edge,
                             int mb_to_bottom_edge)
 {
     int row, col;
     int non_zero_count = 0;
     MV * const filtered_mv = &(mi->mbmi.mv.as_mv);
     union b_mode_info * const bmi = mi->bmi;
     filtered_mv->col = 0;
     filtered_mv->row = 0;
     mi->mbmi.need_to_clamp_mvs = 0;
     for (row = 0; row < 4; ++row)
     {
         int this_b_to_top_edge = mb_to_top_edge + ((row*4)<<3);
         int this_b_to_bottom_edge = mb_to_bottom_edge - ((row*4)<<3);
         for (col = 0; col < 4; ++col)
         {
             int i = row * 4 + col;
             int this_b_to_left_edge = mb_to_left_edge + ((col*4)<<3);
             int this_b_to_right_edge = mb_to_right_edge - ((col*4)<<3);
             /* Estimate vectors for all blocks which are overlapped by this */
             /* type. Interpolate/extrapolate the rest of the block's MVs */
             estimate_mv(block_overlaps[i].overlaps, &(bmi[i]));
             mi->mbmi.need_to_clamp_mvs |= vp8_check_mv_bounds(
                                                          &bmi[i].mv,
                                                          this_b_to_left_edge,
                                                          this_b_to_right_edge,
                                                          this_b_to_top_edge,
                                                          this_b_to_bottom_edge);
             if (bmi[i].mv.as_int != 0)
             {
                 ++non_zero_count;
                 filtered_mv->col += bmi[i].mv.as_mv.col;
                 filtered_mv->row += bmi[i].mv.as_mv.row;
             }
         }
     }
     if (non_zero_count > 0)
     {
         filtered_mv->col /= non_zero_count;
         filtered_mv->row /= non_zero_count;
     }
 }
 static void calc_prev_mb_overlaps(MB_OVERLAP *overlaps, MODE_INFO *prev_mi,
                                     int mb_row, int mb_col,
                                     int mb_rows, int mb_cols)
 {
     int sub_row;
     int sub_col;
     for (sub_row = 0; sub_row < 4; ++sub_row)
     {
         for (sub_col = 0; sub_col < 4; ++sub_col)
         {
             vp8_calculate_overlaps(
                                 overlaps, mb_rows, mb_cols,
                                 &(prev_mi->bmi[sub_row * 4 + sub_col]),
 * mb_row + sub_row,
 * mb_col + sub_col);
         }
     }
 }
 /* Estimate all missing motion vectors. This function does the same as the one
  * above, but has different input arguments. */
 static void estimate_missing_mvs(MB_OVERLAP *overlaps,
                                  MODE_INFO *mi, MODE_INFO *prev_mi,
                                  int mb_rows, int mb_cols,
                                  unsigned int first_corrupt)
 {
     int mb_row, mb_col;
     vpx_memset(overlaps, 0, sizeof(MB_OVERLAP) * mb_rows * mb_cols);
     /* First calculate the overlaps for all blocks */
     for (mb_row = 0; mb_row < mb_rows; ++mb_row)
     {
         for (mb_col = 0; mb_col < mb_cols; ++mb_col)
         {
             /* We're only able to use blocks referring to the last frame
              * when extrapolating new vectors.
              */
             if (prev_mi->mbmi.ref_frame == LAST_FRAME)
             {
                 calc_prev_mb_overlaps(overlaps, prev_mi,
                                       mb_row, mb_col,
                                       mb_rows, mb_cols);
             }
             ++prev_mi;
         }
         ++prev_mi;
     }
     mb_row = first_corrupt / mb_cols;
     mb_col = first_corrupt - mb_row * mb_cols;
     mi += mb_row*(mb_cols + 1) + mb_col;
     /* Go through all macroblocks in the current image with missing MVs
      * and calculate new MVs using the overlaps.
      */
     for (; mb_row < mb_rows; ++mb_row)
     {
         int mb_to_top_edge = -((mb_row * 16)) << 3;
         int mb_to_bottom_edge = ((mb_rows - 1 - mb_row) * 16) << 3;
         for (; mb_col < mb_cols; ++mb_col)
         {
             int mb_to_left_edge = -((mb_col * 16) << 3);
             int mb_to_right_edge = ((mb_cols - 1 - mb_col) * 16) << 3;
             const B_OVERLAP *block_overlaps =
                     overlaps[mb_row*mb_cols + mb_col].overlaps;
             mi->mbmi.ref_frame = LAST_FRAME;
             mi->mbmi.mode = SPLITMV;
             mi->mbmi.uv_mode = DC_PRED;
             mi->mbmi.partitioning = 3;
             mi->mbmi.segment_id = 0;
             estimate_mb_mvs(block_overlaps,
                             mi,
                             mb_to_left_edge,
                             mb_to_right_edge,
                             mb_to_top_edge,
                             mb_to_bottom_edge);
             ++mi;
         }
         mb_col = 0;
         ++mi;
     }
 }
 void vp8_estimate_missing_mvs(VP8D_COMP *pbi)
 {
     VP8_COMMON * const pc = &pbi->common;
     estimate_missing_mvs(pbi->overlaps,
                          pc->mi, pc->prev_mi,
                          pc->mb_rows, pc->mb_cols,
                          pbi->mvs_corrupt_from_mb);
 }
 static void assign_neighbor(EC_BLOCK *neighbor, MODE_INFO *mi, int block_idx)
 {
     assert(mi->mbmi.ref_frame < MAX_REF_FRAMES);
     neighbor->ref_frame = mi->mbmi.ref_frame;
     neighbor->mv = mi->bmi[block_idx].mv.as_mv;
 }
 /* Finds the neighboring blocks of a macroblocks. In the general case
  * 20 blocks are found. If a fewer number of blocks are found due to
  * image boundaries, those positions in the EC_BLOCK array are left "empty".
  * The neighbors are enumerated with the upper-left neighbor as the first
  * element, the second element refers to the neighbor to right of the previous
  * neighbor, and so on. The last element refers to the neighbor below the first
  * neighbor.
  */
 static void find_neighboring_blocks(MODE_INFO *mi,
                                     EC_BLOCK *neighbors,
                                     int mb_row, int mb_col,
                                     int mb_rows, int mb_cols,
                                     int mi_stride)
 {
     int i = 0;
     int j;
     if (mb_row > 0)
     {
         /* upper left */
         if (mb_col > 0)
             assign_neighbor(&neighbors[i], mi - mi_stride - 1, 15);
         ++i;
         /* above */
         for (j = 12; j < 16; ++j, ++i)
             assign_neighbor(&neighbors[i], mi - mi_stride, j);
     }
     else
         i += 5;
     if (mb_col < mb_cols - 1)
     {
         /* upper right */
         if (mb_row > 0)
             assign_neighbor(&neighbors[i], mi - mi_stride + 1, 12);
         ++i;
         /* right */
         for (j = 0; j <= 12; j += 4, ++i)
             assign_neighbor(&neighbors[i], mi + 1, j);
     }
     else
         i += 5;
     if (mb_row < mb_rows - 1)
     {
         /* lower right */
         if (mb_col < mb_cols - 1)
             assign_neighbor(&neighbors[i], mi + mi_stride + 1, 0);
         ++i;
         /* below */
         for (j = 0; j < 4; ++j, ++i)
             assign_neighbor(&neighbors[i], mi + mi_stride, j);
     }
     else
         i += 5;
     if (mb_col > 0)
     {
         /* lower left */
         if (mb_row < mb_rows - 1)
             assign_neighbor(&neighbors[i], mi + mi_stride - 1, 4);
         ++i;
         /* left */
         for (j = 3; j < 16; j += 4, ++i)
         {
             assign_neighbor(&neighbors[i], mi - 1, j);
         }
     }
     else
         i += 5;
     assert(i == 20);
 }
 /* Interpolates all motion vectors for a macroblock from the neighboring blocks'
  * motion vectors.
  */
 static void interpolate_mvs(MACROBLOCKD *mb,
                          EC_BLOCK *neighbors,
                          MV_REFERENCE_FRAME dom_ref_frame)
 {
     int row, col, i;
     MODE_INFO * const mi = mb->mode_info_context;
     /* Table with the position of the neighboring blocks relative the position
      * of the upper left block of the current MB. Starting with the upper left
      * neighbor and going to the right.
      */
     const EC_POS neigh_pos[NUM_NEIGHBORS] = {
                                         {-1,-1}, {-1,0}, {-1,1}, {-1,2}, {-1,3},
                                         {-1,4}, {0,4}, {1,4}, {2,4}, {3,4},
                                         {4,4}, {4,3}, {4,2}, {4,1}, {4,0},
                                         {4,-1}, {3,-1}, {2,-1}, {1,-1}, {0,-1}
                                       };
     mi->mbmi.need_to_clamp_mvs = 0;
     for (row = 0; row < 4; ++row)
     {
         int mb_to_top_edge = mb->mb_to_top_edge + ((row*4)<<3);
         int mb_to_bottom_edge = mb->mb_to_bottom_edge - ((row*4)<<3);
         for (col = 0; col < 4; ++col)
         {
             int mb_to_left_edge = mb->mb_to_left_edge + ((col*4)<<3);
             int mb_to_right_edge = mb->mb_to_right_edge - ((col*4)<<3);
             int w_sum = 0;
             int mv_row_sum = 0;
             int mv_col_sum = 0;
             int_mv * const mv = &(mi->bmi[row*4 + col].mv);
             mv->as_int = 0;
             for (i = 0; i < NUM_NEIGHBORS; ++i)
             {
                 /* Calculate the weighted sum of neighboring MVs referring
                  * to the dominant frame type.
                  */
                 const int w = weights_q7[abs(row - neigh_pos[i].row)]
                                         [abs(col - neigh_pos[i].col)];
                 if (neighbors[i].ref_frame != dom_ref_frame)
                     continue;
                 w_sum += w;
                 /* Q7 * Q3 = Q10 */
                 mv_row_sum += w*neighbors[i].mv.row;
                 mv_col_sum += w*neighbors[i].mv.col;
             }
             if (w_sum > 0)
             {
                 /* Avoid division by zero.
                  * Normalize with the sum of the coefficients
                  * Q3 = Q10 / Q7
                  */
                 mv->as_mv.row = mv_row_sum / w_sum;
                 mv->as_mv.col = mv_col_sum / w_sum;
                 mi->mbmi.need_to_clamp_mvs |= vp8_check_mv_bounds(
                                                             mv,
                                                             mb_to_left_edge,
                                                             mb_to_right_edge,
                                                             mb_to_top_edge,
                                                             mb_to_bottom_edge);
             }
         }
     }
 }
 void vp8_interpolate_motion(MACROBLOCKD *mb,
                         int mb_row, int mb_col,
                         int mb_rows, int mb_cols,
                         int mi_stride)
 {
     /* Find relevant neighboring blocks */
     EC_BLOCK neighbors[NUM_NEIGHBORS];
     int i;
     /* Initialize the array. MAX_REF_FRAMES is interpreted as "doesn't exist" */
     for (i = 0; i < NUM_NEIGHBORS; ++i)
     {
         neighbors[i].ref_frame = MAX_REF_FRAMES;
         neighbors[i].mv.row = neighbors[i].mv.col = 0;
     }
     find_neighboring_blocks(mb->mode_info_context,
                                 neighbors,
                                 mb_row, mb_col,
                                 mb_rows, mb_cols,
                                 mb->mode_info_stride);
     /* Interpolate MVs for the missing blocks from the surrounding
      * blocks which refer to the last frame. */
     interpolate_mvs(mb, neighbors, LAST_FRAME);
     mb->mode_info_context->mbmi.ref_frame = LAST_FRAME;
     mb->mode_info_context->mbmi.mode = SPLITMV;
     mb->mode_info_context->mbmi.uv_mode = DC_PRED;
     mb->mode_info_context->mbmi.partitioning = 3;
     mb->mode_info_context->mbmi.segment_id = 0;
 }
 void vp8_conceal_corrupt_mb(MACROBLOCKD *xd)
 {
     /* This macroblock has corrupt residual, use the motion compensated
        image (predictor) for concealment */
     /* The build predictor functions now output directly into the dst buffer,
      * so the copies are no longer necessary */
 }

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media/libvpx/vp8/decoder/error_concealment.c