@@ -381,14 +381,19 @@ static void guess_mv(ERContext *s)

 #define MV_UNCHANGED 1

     const int mb_stride = s->mb_stride;

     const int mb_width  = s->mb_width;

-    const int mb_height = s->mb_height;

+    int mb_height = s->mb_height;

     int i, depth, num_avail;

     int mb_x, mb_y, mot_step, mot_stride;

+    if (s->last_pic.f && s->last_pic.f->data[0])

+        mb_height = FFMIN(mb_height, (s->last_pic.f->height+15)>>4);

+    if (s->next_pic.f && s->next_pic.f->data[0])

+        mb_height = FFMIN(mb_height, (s->next_pic.f->height+15)>>4);

+

     set_mv_strides(s, &mot_step, &mot_stride);

     num_avail = 0;

-    for (i = 0; i < s->mb_num; i++) {

+    for (i = 0; i < mb_width * mb_height; i++) {

         const int mb_xy = s->mb_index2xy[i];

         int f = 0;

         int error = s->error_status_table[mb_xy];

@@ -413,7 +418,7 @@ static void guess_mv(ERContext *s)

     if ((!(s->avctx->error_concealment&FF_EC_GUESS_MVS)) ||

         num_avail <= mb_width / 2) {

-        for (mb_y = 0; mb_y < s->mb_height; mb_y++) {

+        for (mb_y = 0; mb_y < mb_height; mb_y++) {

             for (mb_x = 0; mb_x < s->mb_width; mb_x++) {

                 const int mb_xy = mb_x + mb_y * s->mb_stride;

                 int mv_dir = (s->last_pic.f && s->last_pic.f->data[0]) ? MV_DIR_FORWARD : MV_DIR_BACKWARD;

@@ -442,7 +447,7 @@ static void guess_mv(ERContext *s)

             int score_sum = 0;

             changed = 0;

-            for (mb_y = 0; mb_y < s->mb_height; mb_y++) {

+            for (mb_y = 0; mb_y < mb_height; mb_y++) {

                 for (mb_x = 0; mb_x < s->mb_width; mb_x++) {

                     const int mb_xy        = mb_x + mb_y * s->mb_stride;

                     int mv_predictor[8][2] = { { 0 } };

@@ -675,7 +680,7 @@ skip_last_mv:

         if (none_left)

             return;

-        for (i = 0; i < s->mb_num; i++) {

+        for (i = 0; i < mb_width * mb_height; i++) {

             int mb_xy = s->mb_index2xy[i];

             if (fixed[mb_xy])

                 fixed[mb_xy] = MV_FROZEN;