Merge "Adding error-concealment to the decoder."

12 files changed, 977 insertions, 62 deletions

diff --git a/vp8/common/alloccommon.c b/vp8/common/alloccommon.c
index b0c7363a7..c2e5bfddf 100644
--- a/vp8/common/alloccommon.c
+++ b/vp8/common/alloccommon.c
@@ -27,6 +27,9 @@ static void update_mode_info_border(MODE_INFO *mi, int rows, int cols)
 
     for (i = 0; i < rows; i++)
     {
+        /* TODO(holmer): Bug? This updates the last element of each row
+         * rather than the border element!
+         */
         vpx_memset(&mi[i*cols-1], 0, sizeof(MODE_INFO));
     }
 }
@@ -43,9 +46,11 @@ void vp8_de_alloc_frame_buffers(VP8_COMMON *oci)
 
     vpx_free(oci->above_context);
     vpx_free(oci->mip);
+    vpx_free(oci->prev_mip);
 
     oci->above_context = 0;
     oci->mip = 0;
+    oci->prev_mip = 0;
 
 }
 
@@ -110,6 +115,21 @@ int vp8_alloc_frame_buffers(VP8_COMMON *oci, int width, int height)
 
     oci->mi = oci->mip + oci->mode_info_stride + 1;
 
+    /* allocate memory for last frame MODE_INFO array */
+#if CONFIG_ERROR_CONCEALMENT
+    oci->prev_mip = vpx_calloc((oci->mb_cols + 1) * (oci->mb_rows + 1), sizeof(MODE_INFO));
+
+    if (!oci->prev_mip)
+    {
+        vp8_de_alloc_frame_buffers(oci);
+        return 1;
+    }
+
+    oci->prev_mi = oci->prev_mip + oci->mode_info_stride + 1;
+#else
+    oci->prev_mip = NULL;
+    oci->prev_mi = NULL;
+#endif
 
     oci->above_context = vpx_calloc(sizeof(ENTROPY_CONTEXT_PLANES) * oci->mb_cols, 1);
 
@@ -120,6 +140,7 @@ int vp8_alloc_frame_buffers(VP8_COMMON *oci, int width, int height)
     }
 
     update_mode_info_border(oci->mi, oci->mb_rows, oci->mb_cols);
+    update_mode_info_border(oci->prev_mi, oci->mb_rows, oci->mb_cols);
 
     return 0;
 }
diff --git a/vp8/common/onyxc_int.h b/vp8/common/onyxc_int.h
index cf29d03df..862307ebb 100644
--- a/vp8/common/onyxc_int.h
+++ b/vp8/common/onyxc_int.h
@@ -139,6 +139,8 @@ typedef struct VP8Common
 
     MODE_INFO *mip; /* Base of allocated array */
     MODE_INFO *mi;  /* Corresponds to upper left visible macroblock */
+    MODE_INFO *prev_mip; /* MODE_INFO array 'mip' from last decoded frame */
+    MODE_INFO *prev_mi;  /* 'mi' from last frame (points into prev_mip) */
 
 
     INTERPOLATIONFILTERTYPE mcomp_filter_type;
diff --git a/vp8/common/onyxd.h b/vp8/common/onyxd.h
index e53bc3138..140dc5728 100644
--- a/vp8/common/onyxd.h
+++ b/vp8/common/onyxd.h
@@ -31,6 +31,7 @@ extern "C"
         int     Version;
         int     postprocess;
         int     max_threads;
+        int     error_concealment;
     } VP8D_CONFIG;
     typedef enum
     {
diff --git a/vp8/decoder/decodemv.c b/vp8/decoder/decodemv.c
index 4de28688b..cd67536bc 100644
--- a/vp8/decoder/decodemv.c
+++ b/vp8/decoder/decodemv.c
@@ -244,6 +244,12 @@ static void mb_mode_mv_init(VP8D_COMP *pbi)
     vp8_reader *const bc = & pbi->bc;
     MV_CONTEXT *const mvc = pbi->common.fc.mvc;
 
+#if CONFIG_ERROR_CONCEALMENT
+    /* Default is that no macroblock is corrupt, therefore we initialize
+     * mvs_corrupt_from_mb to something very big, which we can be sure is
+     * outside the frame. */
+    pbi->mvs_corrupt_from_mb = UINT_MAX;
+#endif
     pbi->prob_skip_false = 0;
     if (pbi->common.mb_no_coeff_skip)
         pbi->prob_skip_false = (vp8_prob)vp8_read_literal(bc, 8);
@@ -280,6 +286,7 @@ static void mb_mode_mv_init(VP8D_COMP *pbi)
     }
 }
 
+
 static void read_mb_modes_mv(VP8D_COMP *pbi, MODE_INFO *mi, MB_MODE_INFO *mbmi,
                             int mb_row, int mb_col)
 {
@@ -403,7 +410,7 @@ static void read_mb_modes_mv(VP8D_COMP *pbi, MODE_INFO *mi, MB_MODE_INFO *mbmi,
 
                     do {
                         mi->bmi[ *fill_offset] = bmi;
-                      fill_offset++;
+                        fill_offset++;
 
                     }while (--fill_count);
                 }
@@ -524,12 +531,26 @@ void vp8_decode_mode_mvs(VP8D_COMP *pbi)
 
         while (++mb_col < pbi->common.mb_cols)
         {
+            int mb_num = mb_row * pbi->common.mb_cols + mb_col;
             /*read_mb_modes_mv(pbi, xd->mode_info_context, &xd->mode_info_context->mbmi, mb_row, mb_col);*/
             if(pbi->common.frame_type == KEY_FRAME)
                 vp8_kfread_modes(pbi, mi, mb_row, mb_col);
             else
                 read_mb_modes_mv(pbi, mi, &mi->mbmi, mb_row, mb_col);
 
+#if CONFIG_ERROR_CONCEALMENT
+            /* look for corruption. set mvs_corrupt_from_mb to the current
+             * mb_num if the frame is corrupt from this macroblock. */
+            if (vp8dx_bool_error(&pbi->bc) && mb_num < pbi->mvs_corrupt_from_mb)
+            {
+                pbi->mvs_corrupt_from_mb = mb_num;
+                /* no need to continue since the partition is corrupt from
+                 * here on.
+                 */
+                return;
+            }
+#endif
+
             mi++;       /* next macroblock */
         }
 
diff --git a/vp8/decoder/decodframe.c b/vp8/decoder/decodframe.c
index a585f774c..f8e04a7d0 100644
--- a/vp8/decoder/decodframe.c
+++ b/vp8/decoder/decodframe.c
@@ -27,6 +27,9 @@
 
 #include "decodemv.h"
 #include "vp8/common/extend.h"
+#if CONFIG_ERROR_CONCEALMENT
+#include "error_concealment.h"
+#endif
 #include "vpx_mem/vpx_mem.h"
 #include "vp8/common/idct.h"
 #include "dequantize.h"
@@ -176,7 +179,8 @@ void clamp_mvs(MACROBLOCKD *xd)
 
 }
 
-static void decode_macroblock(VP8D_COMP *pbi, MACROBLOCKD *xd)
+static void decode_macroblock(VP8D_COMP *pbi, MACROBLOCKD *xd,
+                              unsigned int mb_idx)
 {
     int eobtotal = 0;
     int i, do_clamp = xd->mode_info_context->mbmi.need_to_clamp_mvs;
@@ -233,6 +237,19 @@ static void decode_macroblock(VP8D_COMP *pbi, MACROBLOCKD *xd)
         vp8_build_inter_predictors_mb(xd);
     }
 
+#if CONFIG_ERROR_CONCEALMENT
+    if (pbi->ec_enabled &&
+        (mb_idx > pbi->mvs_corrupt_from_mb ||
+        vp8dx_bool_error(xd->current_bc)))
+    {
+        /* MB with corrupt residuals or corrupt mode/motion vectors.
+         * Better to use the predictor as reconstruction.
+         */
+        vp8_conceal_corrupt_mb(xd);
+        return;
+    }
+#endif
+
     /* dequantization and idct */
     if (xd->mode_info_context->mbmi.mode != B_PRED && xd->mode_info_context->mbmi.mode != SPLITMV)
     {
@@ -355,6 +372,32 @@ decode_mb_row(VP8D_COMP *pbi, VP8_COMMON *pc, int mb_row, MACROBLOCKD *xd)
 
     for (mb_col = 0; mb_col < pc->mb_cols; mb_col++)
     {
+        /* Distance of Mb to the various image edges.
+         * These are specified to 8th pel as they are always compared to values
+         * that are in 1/8th pel units
+         */
+        xd->mb_to_left_edge = -((mb_col * 16) << 3);
+        xd->mb_to_right_edge = ((pc->mb_cols - 1 - mb_col) * 16) << 3;
+
+#if CONFIG_ERROR_CONCEALMENT
+        if (pbi->ec_enabled &&
+            xd->mode_info_context->mbmi.ref_frame == INTRA_FRAME &&
+            vp8dx_bool_error(xd->current_bc))
+        {
+            /* We have an intra block with corrupt coefficients, better to
+             * conceal with an inter block. Interpolate MVs from neighboring MBs
+             *
+             * Note that for the first mb with corrupt residual in a frame,
+             * we might not discover that before decoding the residual. That
+             * happens after this check, and therefore no inter concealment will
+             * be done.
+             */
+            vp8_interpolate_motion(xd,
+                                   mb_row, mb_col,
+                                   pc->mb_rows, pc->mb_cols,
+                                   pc->mode_info_stride);
+        }
+#endif
 
         if (xd->mode_info_context->mbmi.mode == SPLITMV || xd->mode_info_context->mbmi.mode == B_PRED)
         {
@@ -365,12 +408,6 @@ decode_mb_row(VP8D_COMP *pbi, VP8_COMMON *pc, int mb_row, MACROBLOCKD *xd)
             }
         }
 
-        /* Distance of Mb to the various image edges.
-         * These are specified to 8th pel as they are always compared to values that are in 1/8th pel units
-         */
-        xd->mb_to_left_edge = -((mb_col * 16) << 3);
-        xd->mb_to_right_edge = ((pc->mb_cols - 1 - mb_col) * 16) << 3;
-
         xd->dst.y_buffer = pc->yv12_fb[dst_fb_idx].y_buffer + recon_yoffset;
         xd->dst.u_buffer = pc->yv12_fb[dst_fb_idx].u_buffer + recon_uvoffset;
         xd->dst.v_buffer = pc->yv12_fb[dst_fb_idx].v_buffer + recon_uvoffset;
@@ -403,7 +440,7 @@ decode_mb_row(VP8D_COMP *pbi, VP8_COMMON *pc, int mb_row, MACROBLOCKD *xd)
         else
         pbi->debugoutput =0;
         */
-        decode_macroblock(pbi, xd);
+        decode_macroblock(pbi, xd, mb_row * pc->mb_cols  + mb_col);
 
         /* check if the boolean decoder has suffered an error */
         xd->corrupted |= vp8dx_bool_error(xd->current_bc);
@@ -477,8 +514,8 @@ static void setup_token_decoder(VP8D_COMP *pbi,
             partition_size = user_data_end - partition;
         }
 
-        if (partition + partition_size > user_data_end
-            || partition + partition_size < partition)
+        if (!pbi->ec_enabled && (partition + partition_size > user_data_end
+            || partition + partition_size < partition))
             vpx_internal_error(&pc->error, VPX_CODEC_CORRUPT_FRAME,
                                "Truncated packet or corrupt partition "
                                "%d length", i + 1);
@@ -593,63 +630,105 @@ int vp8_decode_frame(VP8D_COMP *pbi)
     pc->yv12_fb[pc->new_fb_idx].corrupted = 0;
 
     if (data_end - data < 3)
-        vpx_internal_error(&pc->error, VPX_CODEC_CORRUPT_FRAME,
-                           "Truncated packet");
-    pc->frame_type = (FRAME_TYPE)(data[0] & 1);
-    pc->version = (data[0] >> 1) & 7;
-    pc->show_frame = (data[0] >> 4) & 1;
-    first_partition_length_in_bytes =
-        (data[0] | (data[1] << 8) | (data[2] << 16)) >> 5;
-    data += 3;
-
-    if (data + first_partition_length_in_bytes > data_end
-        || data + first_partition_length_in_bytes < data)
-        vpx_internal_error(&pc->error, VPX_CODEC_CORRUPT_FRAME,
-                           "Truncated packet or corrupt partition 0 length");
-    vp8_setup_version(pc);
-
-    if (pc->frame_type == KEY_FRAME)
     {
-        const int Width = pc->Width;
-        const int Height = pc->Height;
-
-        /* vet via sync code */
-        if (data[0] != 0x9d || data[1] != 0x01 || data[2] != 0x2a)
-            vpx_internal_error(&pc->error, VPX_CODEC_UNSUP_BITSTREAM,
-                               "Invalid frame sync code");
-
-        pc->Width = (data[3] | (data[4] << 8)) & 0x3fff;
-        pc->horiz_scale = data[4] >> 6;
-        pc->Height = (data[5] | (data[6] << 8)) & 0x3fff;
-        pc->vert_scale = data[6] >> 6;
-        data += 7;
-
-        if (Width != pc->Width  ||  Height != pc->Height)
+        if (pbi->ec_enabled)
         {
-            int prev_mb_rows = pc->mb_rows;
+            /* Declare the missing frame as an inter frame since it will
+               be handled as an inter frame when we have estimated its
+               motion vectors. */
+            pc->frame_type = INTER_FRAME;
+            pc->version = 0;
+            pc->show_frame = 1;
+            first_partition_length_in_bytes = 0;
+        }
+        else
+        {
+            vpx_internal_error(&pc->error, VPX_CODEC_CORRUPT_FRAME,
+                               "Truncated packet");
+        }
+    }
+    else
+    {
+        pc->frame_type = (FRAME_TYPE)(data[0] & 1);
+        pc->version = (data[0] >> 1) & 7;
+        pc->show_frame = (data[0] >> 4) & 1;
+        first_partition_length_in_bytes =
+            (data[0] | (data[1] << 8) | (data[2] << 16)) >> 5;
+        data += 3;
+
+        if (!pbi->ec_enabled && (data + first_partition_length_in_bytes > data_end
+            || data + first_partition_length_in_bytes < data))
+            vpx_internal_error(&pc->error, VPX_CODEC_CORRUPT_FRAME,
+                               "Truncated packet or corrupt partition 0 length");
+        vp8_setup_version(pc);
 
-            if (pc->Width <= 0)
+        if (pc->frame_type == KEY_FRAME)
+        {
+            const int Width = pc->Width;
+            const int Height = pc->Height;
+
+            /* vet via sync code */
+            /* When error concealment is enabled we should only check the sync
+             * code if we have enough bits available
+             */
+            if (!pbi->ec_enabled || data + 3 < data_end)
             {
-                pc->Width = Width;
-                vpx_internal_error(&pc->error, VPX_CODEC_CORRUPT_FRAME,
-                                   "Invalid frame width");
+                if (data[0] != 0x9d || data[1] != 0x01 || data[2] != 0x2a)
+                    vpx_internal_error(&pc->error, VPX_CODEC_UNSUP_BITSTREAM,
+                                   "Invalid frame sync code");
             }
 
-            if (pc->Height <= 0)
+            /* If error concealment is enabled we should only parse the new size
+             * if we have enough data. Otherwise we will end up with the wrong
+             * size.
+             */
+            if (!pbi->ec_enabled || data + 6 < data_end)
             {
-                pc->Height = Height;
-                vpx_internal_error(&pc->error, VPX_CODEC_CORRUPT_FRAME,
-                                   "Invalid frame height");
+                pc->Width = (data[3] | (data[4] << 8)) & 0x3fff;
+                pc->horiz_scale = data[4] >> 6;
+                pc->Height = (data[5] | (data[6] << 8)) & 0x3fff;
+                pc->vert_scale = data[6] >> 6;
             }
+            data += 7;
+
+            if (Width != pc->Width  ||  Height != pc->Height)
+            {
+                int prev_mb_rows = pc->mb_rows;
+
+                if (pc->Width <= 0)
+                {
+                    pc->Width = Width;
+                    vpx_internal_error(&pc->error, VPX_CODEC_CORRUPT_FRAME,
+                                       "Invalid frame width");
+                }
+
+                if (pc->Height <= 0)
+                {
+                    pc->Height = Height;
+                    vpx_internal_error(&pc->error, VPX_CODEC_CORRUPT_FRAME,
+                                       "Invalid frame height");
+                }
 
-            if (vp8_alloc_frame_buffers(pc, pc->Width, pc->Height))
-                vpx_internal_error(&pc->error, VPX_CODEC_MEM_ERROR,
-                                   "Failed to allocate frame buffers");
+                if (vp8_alloc_frame_buffers(pc, pc->Width, pc->Height))
+                    vpx_internal_error(&pc->error, VPX_CODEC_MEM_ERROR,
+                                       "Failed to allocate frame buffers");
+
+#if CONFIG_ERROR_CONCEALMENT
+                pbi->overlaps = NULL;
+                if (pbi->ec_enabled)
+                {
+                    if (vp8_alloc_overlap_lists(pbi))
+                        vpx_internal_error(&pc->error, VPX_CODEC_MEM_ERROR,
+                                           "Failed to allocate overlap lists "
+                                           "for error concealment");
+                }
+#endif
 
 #if CONFIG_MULTITHREAD
-            if (pbi->b_multithreaded_rd)
-                vp8mt_alloc_temp_buffers(pbi, pc->Width, prev_mb_rows);
+                if (pbi->b_multithreaded_rd)
+                    vp8mt_alloc_temp_buffers(pbi, pc->Width, prev_mb_rows);
 #endif
+            }
         }
     }
 
@@ -792,7 +871,20 @@ int vp8_decode_frame(VP8D_COMP *pbi)
     {
         /* Should the GF or ARF be updated from the current frame */
         pc->refresh_golden_frame = vp8_read_bit(bc);
+#if CONFIG_ERROR_CONCEALMENT
+        /* Assume we shouldn't refresh golden if the bit is missing */
+        xd->corrupted |= vp8dx_bool_error(bc);
+        if (pbi->ec_enabled && xd->corrupted)
+            pc->refresh_golden_frame = 0;
+#endif
+
         pc->refresh_alt_ref_frame = vp8_read_bit(bc);
+#if CONFIG_ERROR_CONCEALMENT
+        /* Assume we shouldn't refresh altref if the bit is missing */
+        xd->corrupted |= vp8dx_bool_error(bc);
+        if (pbi->ec_enabled && xd->corrupted)
+            pc->refresh_alt_ref_frame = 0;
+#endif
 
         /* Buffer to buffer copy flags. */
         pc->copy_buffer_to_gf = 0;
@@ -817,6 +909,13 @@ int vp8_decode_frame(VP8D_COMP *pbi)
 
     pc->refresh_last_frame = pc->frame_type == KEY_FRAME  ||  vp8_read_bit(bc);
 
+#if CONFIG_ERROR_CONCEALMENT
+    /* Assume we should refresh the last frame if the bit is missing */
+    xd->corrupted |= vp8dx_bool_error(bc);
+    if (pbi->ec_enabled && xd->corrupted)
+        pc->refresh_last_frame = 1;
+#endif
+
     if (0)
     {
         FILE *z = fopen("decodestats.stt", "a");
@@ -872,6 +971,16 @@ int vp8_decode_frame(VP8D_COMP *pbi)
 
     vp8_decode_mode_mvs(pbi);
 
+#if CONFIG_ERROR_CONCEALMENT
+    if (pbi->ec_enabled &&
+            pbi->mvs_corrupt_from_mb < (unsigned int)pc->mb_cols * pc->mb_rows)
+    {
+        /* Motion vectors are missing in this frame. We will try to estimate
+         * them and then continue decoding the frame as usual */
+        vp8_estimate_missing_mvs(pbi);
+    }
+#endif
+
     vpx_memset(pc->above_context, 0, sizeof(ENTROPY_CONTEXT_PLANES) * pc->mb_cols);
 
     vpx_memcpy(&xd->block[0].bmi, &xd->mode_info_context->bmi[0], sizeof(B_MODE_INFO));
diff --git a/vp8/decoder/ec_types.h b/vp8/decoder/ec_types.h
new file mode 100644
index 000000000..a4f8c78b3
--- /dev/null
+++ b/vp8/decoder/ec_types.h
@@ -0,0 +1,49 @@
+/*
+ *  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.
+ */
+
+#ifndef VP8_DEC_EC_TYPES_H
+#define VP8_DEC_EC_TYPES_H
+
+#define MAX_OVERLAPS 16
+
+/* The area (pixel area in Q6) the block pointed to by bmi overlaps
+ * another block with.
+ */
+typedef struct
+{
+    int overlap;
+    B_MODE_INFO *bmi;
+} OVERLAP_NODE;
+
+/* Structure to keep track of overlapping blocks on a block level. */
+typedef struct
+{
+    /* TODO(holmer): This array should be exchanged for a linked list */
+    OVERLAP_NODE overlaps[MAX_OVERLAPS];
+} B_OVERLAP;
+
+/* Structure used to hold all the overlaps of a macroblock. The overlaps of a
+ * macroblock is further divided into block overlaps.
+ */
+typedef struct
+{
+    B_OVERLAP overlaps[16];
+} MB_OVERLAP;
+
+/* Structure for keeping track of motion vectors and which reference frame they
+ * refer to. Used for motion vector interpolation.
+ */
+typedef struct
+{
+    MV mv;
+    MV_REFERENCE_FRAME ref_frame;
+} EC_BLOCK;
+
+#endif /* VP8_DEC_EC_TYPES_H */
diff --git a/vp8/decoder/error_concealment.c b/vp8/decoder/error_concealment.c
new file mode 100644
index 000000000..dcb5c86a5
--- /dev/null
+++ b/vp8/decoder/error_concealment.c
@@ -0,0 +1,613 @@
+/*
+ *  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 "error_concealment.h"
+#include "onyxd_int.h"
+#include "decodemv.h"
+#include "vpx_mem/vpx_mem.h"
+#include "vp8/common/recon.h"
+#include "vp8/common/findnearmv.h"
+
+#include <assert.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;
+    vpx_memset(pbi->overlaps, 0,
+               sizeof(MB_OVERLAP) * pbi->common.mb_rows * pbi->common.mb_cols);
+    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,
+                           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, 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) *
+                                                      4) << 3),
+                                                  (((first_blk_col + col) *
+                                                      4) << 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,
+                            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, 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;
+        bmi->mode = NEW4X4;
+    }
+    else
+    {
+        bmi->mv.as_mv.col = 0;
+        bmi->mv.as_mv.row = 0;
+        bmi->mode = NEW4X4;
+    }
+}
+
+/* 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 i;
+    int non_zero_count = 0;
+    MV * const filtered_mv = &(mi->mbmi.mv.as_mv);
+    B_MODE_INFO * const bmi = mi->bmi;
+    filtered_mv->col = 0;
+    filtered_mv->row = 0;
+    for (i = 0; i < 16; ++i)
+    {
+        /* 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,
+                                                         mb_to_left_edge,
+                                                         mb_to_right_edge,
+                                                         mb_to_top_edge,
+                                                         mb_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]),
+                                4 * mb_row + sub_row,
+                                4 * 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;
+            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);
+}
+
+/* Calculates which reference frame type is dominating among the neighbors */
+static MV_REFERENCE_FRAME dominant_ref_frame(EC_BLOCK *neighbors)
+{
+    /* Default to referring to "skip" */
+    MV_REFERENCE_FRAME dom_ref_frame = LAST_FRAME;
+    int max_ref_frame_cnt = 0;
+    int ref_frame_cnt[MAX_REF_FRAMES] = {0};
+    int i;
+    /* Count neighboring reference frames */
+    for (i = 0; i < NUM_NEIGHBORS; ++i)
+    {
+        if (neighbors[i].ref_frame < MAX_REF_FRAMES &&
+            neighbors[i].ref_frame != INTRA_FRAME)
+            ++ref_frame_cnt[neighbors[i].ref_frame];
+    }
+    /* Find maximum */
+    for (i = 0; i < MAX_REF_FRAMES; ++i)
+    {
+        if (ref_frame_cnt[i] > max_ref_frame_cnt)
+        {
+            dom_ref_frame = i;
+            max_ref_frame_cnt = ref_frame_cnt[i];
+        }
+    }
+    return dom_ref_frame;
+}
+
+/* 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}
+                                      };
+    for (row = 0; row < 4; ++row)
+    {
+        for (col = 0; col < 4; ++col)
+        {
+            int w_sum = 0;
+            int mv_row_sum = 0;
+            int mv_col_sum = 0;
+            int_mv * const mv = &(mi->bmi[row*4 + col].mv);
+            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->bmi[row*4 + col].mode = NEW4X4;
+                mi->mbmi.need_to_clamp_mvs = vp8_check_mv_bounds(mv,
+                                                       mb->mb_to_left_edge,
+                                                       mb->mb_to_right_edge,
+                                                       mb->mb_to_top_edge,
+                                                       mb->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];
+    MV_REFERENCE_FRAME dom_ref_frame;
+    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);
+    /* Determine the dominant block type */
+    dom_ref_frame = dominant_ref_frame(neighbors);
+    /* Interpolate MVs for the missing blocks
+     * from the dominating MVs */
+    interpolate_mvs(mb, neighbors, dom_ref_frame);
+
+    mb->mode_info_context->mbmi.ref_frame = dom_ref_frame;
+    mb->mode_info_context->mbmi.mode = SPLITMV;
+    mb->mode_info_context->mbmi.uv_mode = DC_PRED;
+    mb->mode_info_context->mbmi.partitioning = 3;
+}
+
+void vp8_conceal_corrupt_mb(MACROBLOCKD *xd)
+{
+    /* This macroblock has corrupt residual, use the motion compensated
+       image (predictor) for concealment */
+    vp8_recon_copy16x16(xd->predictor, 16, xd->dst.y_buffer, xd->dst.y_stride);
+    vp8_recon_copy8x8(xd->predictor + 256, 8,
+                      xd->dst.u_buffer, xd->dst.uv_stride);
+    vp8_recon_copy8x8(xd->predictor + 320, 8,
+                      xd->dst.v_buffer, xd->dst.uv_stride);
+}
diff --git a/vp8/decoder/error_concealment.h b/vp8/decoder/error_concealment.h
new file mode 100644
index 000000000..65ae9d9be
--- /dev/null
+++ b/vp8/decoder/error_concealment.h
@@ -0,0 +1,41 @@
+/*
+ *  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.
+ */
+
+
+#ifndef ERROR_CONCEALMENT_H
+#define ERROR_CONCEALMENT_H
+
+#include "onyxd_int.h"
+#include "ec_types.h"
+
+/* Allocate memory for the overlap lists */
+int vp8_alloc_overlap_lists(VP8D_COMP *pbi);
+
+/* Deallocate the overlap lists */
+void vp8_de_alloc_overlap_lists(VP8D_COMP *pbi);
+
+/* Estimate all missing motion vectors. */
+void vp8_estimate_missing_mvs(VP8D_COMP *pbi);
+
+/* Functions for spatial MV interpolation */
+
+/* Interpolates all motion vectors for a macroblock mb at position
+ * (mb_row, mb_col). */
+void vp8_interpolate_motion(MACROBLOCKD *mb,
+                            int mb_row, int mb_col,
+                            int mb_rows, int mb_cols,
+                            int mi_stride);
+
+/* Conceal a macroblock with corrupt residual.
+ * Copies the prediction signal to the reconstructed image.
+ */
+void vp8_conceal_corrupt_mb(MACROBLOCKD *xd);
+
+#endif
diff --git a/vp8/decoder/onyxd_if.c b/vp8/decoder/onyxd_if.c
index 1e83ab542..705fb334f 100644
--- a/vp8/decoder/onyxd_if.c
+++ b/vp8/decoder/onyxd_if.c
@@ -30,6 +30,9 @@
 #include "vp8/common/systemdependent.h"
 #include "vpx_ports/vpx_timer.h"
 #include "detokenize.h"
+#if CONFIG_ERROR_CONCEALMENT
+#include "error_concealment.h"
+#endif
 #if ARCH_ARM
 #include "vpx_ports/arm.h"
 #endif
@@ -96,6 +99,13 @@ VP8D_PTR vp8dx_create_decompressor(VP8D_CONFIG *oxcf)
     }
 
     pbi->common.error.setjmp = 0;
+
+#if CONFIG_ERROR_CONCEALMENT
+    pbi->ec_enabled = oxcf->error_concealment;
+#else
+    pbi->ec_enabled = 0;
+#endif
+
     return (VP8D_PTR) pbi;
 }
 
@@ -112,6 +122,9 @@ void vp8dx_remove_decompressor(VP8D_PTR ptr)
         vp8mt_de_alloc_temp_buffers(pbi, pbi->common.mb_rows);
     vp8_decoder_remove_threads(pbi);
 #endif
+#if CONFIG_ERROR_CONCEALMENT
+    vp8_de_alloc_overlap_lists(pbi);
+#endif
     vp8_remove_common(&pbi->common);
     vpx_free(pbi);
 }
@@ -271,11 +284,17 @@ int vp8dx_receive_compressed_data(VP8D_PTR ptr, unsigned long size, const unsign
         */
         cm->yv12_fb[cm->lst_fb_idx].corrupted = 1;
 
-        /* Signal that we have no frame to show. */
-        cm->show_frame = 0;
+        /* If error concealment is disabled we won't signal missing frames to
+         * the decoder.
+         */
+        if (!pbi->ec_enabled)
+        {
+            /* Signal that we have no frame to show. */
+            cm->show_frame = 0;
 
-        /* Nothing more to do. */
-        return 0;
+            /* Nothing more to do. */
+            return 0;
+        }
     }
 
 
@@ -388,6 +407,28 @@ int vp8dx_receive_compressed_data(VP8D_PTR ptr, unsigned long size, const unsign
 
     vp8_clear_system_state();
 
+#if CONFIG_ERROR_CONCEALMENT
+    /* swap the mode infos to storage for future error concealment */
+    if (pbi->ec_enabled && pbi->common.prev_mi)
+    {
+        const MODE_INFO* tmp = pbi->common.prev_mi;
+        int row, col;
+        pbi->common.prev_mi = pbi->common.mi;
+        pbi->common.mi = tmp;
+
+        /* Propagate the segment_ids to the next frame */
+        for (row = 0; row < pbi->common.mb_rows; ++row)
+        {
+            for (col = 0; col < pbi->common.mb_cols; ++col)
+            {
+                const int i = row*pbi->common.mode_info_stride + col;
+                pbi->common.mi[i].mbmi.segment_id =
+                        pbi->common.prev_mi[i].mbmi.segment_id;
+            }
+        }
+    }
+#endif
+
     /*vp8_print_modes_and_motion_vectors( cm->mi, cm->mb_rows,cm->mb_cols, cm->current_video_frame);*/
 
     if (cm->show_frame)
diff --git a/vp8/decoder/onyxd_int.h b/vp8/decoder/onyxd_int.h
index 9b9175628..ea6de3dda 100644
--- a/vp8/decoder/onyxd_int.h
+++ b/vp8/decoder/onyxd_int.h
@@ -17,6 +17,9 @@
 #include "vp8/common/onyxc_int.h"
 #include "vp8/common/threading.h"
 #include "dequantize.h"
+#if CONFIG_ERROR_CONCEALMENT
+#include "ec_types.h"
+#endif
 
 typedef struct
 {
@@ -128,6 +131,13 @@ typedef struct VP8Decompressor
     vp8_prob prob_gf;
     vp8_prob prob_skip_false;
 
+#if CONFIG_ERROR_CONCEALMENT
+    MB_OVERLAP *overlaps;
+    /* the mb num from which modes and mvs (first partition) are corrupt */
+    unsigned int mvs_corrupt_from_mb;
+#endif
+    int ec_enabled;
+
 } VP8D_COMP;
 
 int vp8_decode_frame(VP8D_COMP *cpi);
diff --git a/vp8/vp8_dx_iface.c b/vp8/vp8_dx_iface.c
index cca17c23d..e0f4c0a96 100644
--- a/vp8/vp8_dx_iface.c
+++ b/vp8/vp8_dx_iface.c
@@ -19,6 +19,8 @@
 #include "decoder/onyxd_int.h"
 
 #define VP8_CAP_POSTPROC (CONFIG_POSTPROC ? VPX_CODEC_CAP_POSTPROC : 0)
+#define VP8_CAP_ERROR_CONCEALMENT (CONFIG_ERROR_CONCEALMENT ? \
+                                    VPX_CODEC_CAP_ERROR_CONCEALMENT : 0)
 
 typedef vpx_codec_stream_info_t  vp8_stream_info_t;
 
@@ -364,6 +366,8 @@ static vpx_codec_err_t vp8_decode(vpx_codec_alg_priv_t  *ctx,
             oxcf.Version = 9;
             oxcf.postprocess = 0;
             oxcf.max_threads = ctx->cfg.threads;
+            oxcf.error_concealment =
+                    (ctx->base.init_flags & VPX_CODEC_USE_ERROR_CONCEALMENT);
 
             optr = vp8dx_create_decompressor(&oxcf);
 
@@ -719,7 +723,7 @@ CODEC_INTERFACE(vpx_codec_vp8_dx) =
 {
     "WebM Project VP8 Decoder" VERSION_STRING,
     VPX_CODEC_INTERNAL_ABI_VERSION,
-    VPX_CODEC_CAP_DECODER | VP8_CAP_POSTPROC,
+    VPX_CODEC_CAP_DECODER | VP8_CAP_POSTPROC | VP8_CAP_ERROR_CONCEALMENT,
     /* vpx_codec_caps_t          caps; */
     vp8_init,         /* vpx_codec_init_fn_t       init; */
     vp8_destroy,      /* vpx_codec_destroy_fn_t    destroy; */
@@ -749,7 +753,7 @@ vpx_codec_iface_t vpx_codec_vp8_algo =
 {
     "WebM Project VP8 Decoder (Deprecated API)" VERSION_STRING,
     VPX_CODEC_INTERNAL_ABI_VERSION,
-    VPX_CODEC_CAP_DECODER | VP8_CAP_POSTPROC,
+    VPX_CODEC_CAP_DECODER | VP8_CAP_POSTPROC | VP8_CAP_ERROR_CONCEALMENT,
     /* vpx_codec_caps_t          caps; */
     vp8_init,         /* vpx_codec_init_fn_t       init; */
     vp8_destroy,      /* vpx_codec_destroy_fn_t    destroy; */
diff --git a/vp8/vp8dx.mk b/vp8/vp8dx.mk
index 564967191..85d6f513e 100644
--- a/vp8/vp8dx.mk
+++ b/vp8/vp8dx.mk
@@ -53,6 +53,9 @@ VP8_DX_SRCS-yes += decoder/decodemv.c
 VP8_DX_SRCS-yes += decoder/decodframe.c
 VP8_DX_SRCS-yes += decoder/dequantize.c
 VP8_DX_SRCS-yes += decoder/detokenize.c
+VP8_DX_SRCS-$(CONFIG_ERROR_CONCEALMENT) += decoder/ec_types.h
+VP8_DX_SRCS-$(CONFIG_ERROR_CONCEALMENT) += decoder/error_concealment.h
+VP8_DX_SRCS-$(CONFIG_ERROR_CONCEALMENT) += decoder/error_concealment.c
 VP8_DX_SRCS-yes += decoder/generic/dsystemdependent.c
 VP8_DX_SRCS-yes += decoder/dboolhuff.h
 VP8_DX_SRCS-yes += decoder/decodemv.h