diff --git a/libavcodec/arm/h264idct_neon.S b/libavcodec/arm/h264idct_neon.S
index b23ddb1b73..3e5321cd05 100644
--- a/libavcodec/arm/h264idct_neon.S
+++ b/libavcodec/arm/h264idct_neon.S
@@ -22,9 +22,12 @@
 
 function ff_h264_idct_add_neon, export=1
         vld1.64         {d0-d3},  [r1,:128]
+        vmov.i16        q15, #0
 
         vswp            d1,  d2
+        vst1.16         {q15},    [r1,:128]!
         vadd.i16        d4,  d0,  d1
+        vst1.16         {q15},    [r1,:128]!
         vshr.s16        q8,  q1,  #1
         vsub.i16        d5,  d0,  d1
         vadd.i16        d6,  d2,  d17
@@ -65,11 +68,14 @@ function ff_h264_idct_add_neon, export=1
         vst1.32         {d0[1]},  [r0,:32], r2
         vst1.32         {d1[0]},  [r0,:32], r2
 
+        sub             r1,  r1,  #32
         bx              lr
 endfunc
 
 function ff_h264_idct_dc_add_neon, export=1
+        mov             r3,       #0
         vld1.16         {d2[],d3[]}, [r1,:16]
+        strh            r3,       [r1]
         vrshr.s16       q1,  q1,  #6
         vld1.32         {d0[0]},  [r0,:32], r2
         vld1.32         {d0[1]},  [r0,:32], r2
@@ -148,7 +154,7 @@ function ff_h264_idct_add8_neon, export=1
         add             r5,  r1,  #16*4
         add             r1,  r2,  #16*32
         mov             r2,  r3
-        mov             r3,  r1
+        mov             r10, r1
         ldr             r6,  [sp, #32]
         movrel          r7,  scan8+16
         mov             r12, #0
@@ -156,7 +162,7 @@ function ff_h264_idct_add8_neon, export=1
         ldr             r0,  [r5, r12, lsl #2]
         ldrb            r8,  [r6, r8]
         add             r0,  r0,  r4
-        add             r1,  r3,  r12, lsl #5
+        add             r1,  r10, r12, lsl #5
         cmp             r8,  #0
         ldrsh           r8,  [r1]
         iteet           ne
@@ -180,7 +186,9 @@ endfunc
         qb      .req    q14
         vshr.s16        q2,  q10, #1
         vadd.i16        q0,  q8,  q12
-        vld1.16         {q14-q15},[r1,:128]!
+        vld1.16         {q14-q15},[r1,:128]
+        vst1.16         {q3},     [r1,:128]!
+        vst1.16         {q3},     [r1,:128]!
         vsub.i16        q1,  q8,  q12
         vshr.s16        q3,  q14, #1
         vsub.i16        q2,  q2,  q14
@@ -259,9 +267,16 @@ endfunc
 .endm
 
 function ff_h264_idct8_add_neon, export=1
-        vld1.16         {q8-q9},  [r1,:128]!
-        vld1.16         {q10-q11},[r1,:128]!
-        vld1.16         {q12-q13},[r1,:128]!
+        vmov.i16        q3,       #0
+        vld1.16         {q8-q9},  [r1,:128]
+        vst1.16         {q3},     [r1,:128]!
+        vst1.16         {q3},     [r1,:128]!
+        vld1.16         {q10-q11},[r1,:128]
+        vst1.16         {q3},     [r1,:128]!
+        vst1.16         {q3},     [r1,:128]!
+        vld1.16         {q12-q13},[r1,:128]
+        vst1.16         {q3},     [r1,:128]!
+        vst1.16         {q3},     [r1,:128]!
 
         idct8x8_cols    0
         idct8x8_cols    1
@@ -313,7 +328,9 @@ function ff_h264_idct8_add_neon, export=1
 endfunc
 
 function ff_h264_idct8_dc_add_neon, export=1
+        mov             r3,       #0
         vld1.16         {d30[],d31[]},[r1,:16]
+        strh            r3,       [r1]
         vld1.32         {d0},     [r0,:64], r2
         vrshr.s16       q15, q15, #6
         vld1.32         {d1},     [r0,:64], r2
diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index bfe9940738..7d7f37601a 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -2257,7 +2257,7 @@ static av_always_inline void hl_decode_mb_predict_luma(H264Context *h,
         if (IS_8x8DCT(mb_type)) {
             if (transform_bypass) {
                 idct_dc_add  =
-                idct_add     = h->h264dsp.h264_add_pixels8;
+                idct_add     = h->h264dsp.h264_add_pixels8_clear;
             } else {
                 idct_dc_add = h->h264dsp.h264_idct8_dc_add;
                 idct_add    = h->h264dsp.h264_idct8_add;
@@ -2282,7 +2282,7 @@ static av_always_inline void hl_decode_mb_predict_luma(H264Context *h,
         } else {
             if (transform_bypass) {
                 idct_dc_add  =
-                idct_add     = h->h264dsp.h264_add_pixels4;
+                idct_add     = h->h264dsp.h264_add_pixels4_clear;
             } else {
                 idct_dc_add = h->h264dsp.h264_idct_dc_add;
                 idct_add    = h->h264dsp.h264_idct_add;
@@ -2379,9 +2379,9 @@ static av_always_inline void hl_decode_mb_idct_luma(H264Context *h, int mb_type,
                         for (i = 0; i < 16; i++)
                             if (h->non_zero_count_cache[scan8[i + p * 16]] ||
                                 dctcoef_get(h->mb, pixel_shift, i * 16 + p * 256))
-                                h->h264dsp.h264_add_pixels4(dest_y + block_offset[i],
-                                                            h->mb + (i * 16 + p * 256 << pixel_shift),
-                                                            linesize);
+                                h->h264dsp.h264_add_pixels4_clear(dest_y + block_offset[i],
+                                                                  h->mb + (i * 16 + p * 256 << pixel_shift),
+                                                                  linesize);
                     }
                 } else {
                     h->h264dsp.h264_idct_add16intra(dest_y, block_offset,
@@ -2392,8 +2392,8 @@ static av_always_inline void hl_decode_mb_idct_luma(H264Context *h, int mb_type,
             } else if (h->cbp & 15) {
                 if (transform_bypass) {
                     const int di = IS_8x8DCT(mb_type) ? 4 : 1;
-                    idct_add = IS_8x8DCT(mb_type) ? h->h264dsp.h264_add_pixels8
-                                                  : h->h264dsp.h264_add_pixels4;
+                    idct_add = IS_8x8DCT(mb_type) ? h->h264dsp.h264_add_pixels8_clear
+                                                  : h->h264dsp.h264_add_pixels4_clear;
                     for (i = 0; i < 16; i += di)
                         if (h->non_zero_count_cache[scan8[i + p * 16]])
                             idct_add(dest_y + block_offset[i],
diff --git a/libavcodec/h264_mb_template.c b/libavcodec/h264_mb_template.c
index 957260a081..9b63fefeda 100644
--- a/libavcodec/h264_mb_template.c
+++ b/libavcodec/h264_mb_template.c
@@ -207,7 +207,7 @@ static av_noinline void FUNC(hl_decode_mb)(H264Context *h)
                                                             h->mb + (16 * 16 * 2 << PIXEL_SHIFT),
                                                             uvlinesize);
                 } else {
-                    idct_add = h->h264dsp.h264_add_pixels4;
+                    idct_add = h->h264dsp.h264_add_pixels4_clear;
                     for (j = 1; j < 3; j++) {
                         for (i = j * 16; i < j * 16 + 4; i++)
                             if (h->non_zero_count_cache[scan8[i]] ||
@@ -261,10 +261,6 @@ static av_noinline void FUNC(hl_decode_mb)(H264Context *h)
                 }
             }
         }
-        if (h->cbp || IS_INTRA(mb_type)) {
-            h->dsp.clear_blocks(h->mb);
-            h->dsp.clear_blocks(h->mb + (24 * 16 << PIXEL_SHIFT));
-        }
     }
 }
 
@@ -368,11 +364,6 @@ static av_noinline void FUNC(hl_decode_mb_444)(H264Context *h)
             hl_decode_mb_idct_luma(h, mb_type, 1, SIMPLE, transform_bypass,
                                    PIXEL_SHIFT, block_offset, linesize,
                                    dest[p], p);
-
-        if (h->cbp || IS_INTRA(mb_type)) {
-            h->dsp.clear_blocks(h->mb);
-            h->dsp.clear_blocks(h->mb + (24 * 16 << PIXEL_SHIFT));
-        }
     }
 }
 
diff --git a/libavcodec/h264addpx_template.c b/libavcodec/h264addpx_template.c
index d1babc54e5..cdbfc67dfe 100644
--- a/libavcodec/h264addpx_template.c
+++ b/libavcodec/h264addpx_template.c
@@ -43,6 +43,8 @@ static void FUNCC(ff_h264_add_pixels4)(uint8_t *_dst, int16_t *_src, int stride)
         dst += stride;
         src += 4;
     }
+
+    memset(_src, 0, sizeof(dctcoef) * 16);
 }
 
 static void FUNCC(ff_h264_add_pixels8)(uint8_t *_dst, int16_t *_src, int stride)
@@ -65,4 +67,6 @@ static void FUNCC(ff_h264_add_pixels8)(uint8_t *_dst, int16_t *_src, int stride)
         dst += stride;
         src += 8;
     }
+
+    memset(_src, 0, sizeof(dctcoef) * 64);
 }
diff --git a/libavcodec/h264dsp.c b/libavcodec/h264dsp.c
index b739758e24..8a70aefedc 100644
--- a/libavcodec/h264dsp.c
+++ b/libavcodec/h264dsp.c
@@ -57,8 +57,8 @@ void ff_h264dsp_init(H264DSPContext *c, const int bit_depth, const int chroma_fo
 #define FUNC(a, depth) a ## _ ## depth ## _c
 
 #define ADDPX_DSP(depth) \
-    c->h264_add_pixels4 = FUNC(ff_h264_add_pixels4, depth);\
-    c->h264_add_pixels8 = FUNC(ff_h264_add_pixels8, depth)
+    c->h264_add_pixels4_clear = FUNC(ff_h264_add_pixels4, depth);\
+    c->h264_add_pixels8_clear = FUNC(ff_h264_add_pixels8, depth)
 
     if (bit_depth > 8 && bit_depth <= 16) {
         ADDPX_DSP(16);
diff --git a/libavcodec/h264dsp.h b/libavcodec/h264dsp.h
index 757caf8162..1f9f8fe823 100644
--- a/libavcodec/h264dsp.h
+++ b/libavcodec/h264dsp.h
@@ -103,8 +103,8 @@ typedef struct H264DSPContext {
     void (*h264_chroma_dc_dequant_idct)(int16_t *block, int qmul);
 
     /* bypass-transform */
-    void (*h264_add_pixels8)(uint8_t *dst, int16_t *block, int stride);
-    void (*h264_add_pixels4)(uint8_t *dst, int16_t *block, int stride);
+    void (*h264_add_pixels8_clear)(uint8_t *dst, int16_t *block, int stride);
+    void (*h264_add_pixels4_clear)(uint8_t *dst, int16_t *block, int stride);
 } H264DSPContext;
 
 void ff_h264dsp_init(H264DSPContext *c, const int bit_depth,
diff --git a/libavcodec/h264idct_template.c b/libavcodec/h264idct_template.c
index fc285c57b0..aadafaddd2 100644
--- a/libavcodec/h264idct_template.c
+++ b/libavcodec/h264idct_template.c
@@ -61,6 +61,8 @@ void FUNCC(ff_h264_idct_add)(uint8_t *_dst, int16_t *_block, int stride)
         dst[i + 2*stride]= av_clip_pixel(dst[i + 2*stride] + ((z1 - z2) >> 6));
         dst[i + 3*stride]= av_clip_pixel(dst[i + 3*stride] + ((z0 - z3) >> 6));
     }
+
+    memset(block, 0, 16 * sizeof(dctcoef));
 }
 
 void FUNCC(ff_h264_idct8_add)(uint8_t *_dst, int16_t *_block, int stride){
@@ -133,14 +135,18 @@ void FUNCC(ff_h264_idct8_add)(uint8_t *_dst, int16_t *_block, int stride){
         dst[i + 6*stride] = av_clip_pixel( dst[i + 6*stride] + ((b2 - b5) >> 6) );
         dst[i + 7*stride] = av_clip_pixel( dst[i + 7*stride] + ((b0 - b7) >> 6) );
     }
+
+    memset(block, 0, 64 * sizeof(dctcoef));
 }
 
 // assumes all AC coefs are 0
-void FUNCC(ff_h264_idct_dc_add)(uint8_t *_dst, int16_t *block, int stride){
+void FUNCC(ff_h264_idct_dc_add)(uint8_t *_dst, int16_t *_block, int stride){
     int i, j;
-    int dc = (((dctcoef*)block)[0] + 32) >> 6;
     pixel *dst = (pixel*)_dst;
+    dctcoef *block = (dctcoef*)_block;
+    int dc = (block[0] + 32) >> 6;
     stride /= sizeof(pixel);
+    block[0] = 0;
     for( j = 0; j < 4; j++ )
     {
         for( i = 0; i < 4; i++ )
@@ -149,10 +155,12 @@ void FUNCC(ff_h264_idct_dc_add)(uint8_t *_dst, int16_t *block, int stride){
     }
 }
 
-void FUNCC(ff_h264_idct8_dc_add)(uint8_t *_dst, int16_t *block, int stride){
+void FUNCC(ff_h264_idct8_dc_add)(uint8_t *_dst, int16_t *_block, int stride){
     int i, j;
-    int dc = (((dctcoef*)block)[0] + 32) >> 6;
     pixel *dst = (pixel*)_dst;
+    dctcoef *block = (dctcoef*)_block;
+    int dc = (block[0] + 32) >> 6;
+    block[0] = 0;
     stride /= sizeof(pixel);
     for( j = 0; j < 8; j++ )
     {
diff --git a/libavcodec/h264pred.h b/libavcodec/h264pred.h
index ad1739a3c5..62e5b79dc8 100644
--- a/libavcodec/h264pred.h
+++ b/libavcodec/h264pred.h
@@ -98,15 +98,15 @@ typedef struct H264PredContext {
     void(*pred16x16[4 + 3 + 2])(uint8_t *src, ptrdiff_t stride);
 
     void(*pred4x4_add[2])(uint8_t *pix /*align  4*/,
-                          const int16_t *block /*align 16*/, ptrdiff_t stride);
+                          int16_t *block /*align 16*/, ptrdiff_t stride);
     void(*pred8x8l_add[2])(uint8_t *pix /*align  8*/,
-                           const int16_t *block /*align 16*/, ptrdiff_t stride);
+                           int16_t *block /*align 16*/, ptrdiff_t stride);
     void(*pred8x8_add[3])(uint8_t *pix /*align  8*/,
                           const int *block_offset,
-                          const int16_t *block /*align 16*/, ptrdiff_t stride);
+                          int16_t *block /*align 16*/, ptrdiff_t stride);
     void(*pred16x16_add[3])(uint8_t *pix /*align 16*/,
                             const int *block_offset,
-                            const int16_t *block /*align 16*/, ptrdiff_t stride);
+                            int16_t *block /*align 16*/, ptrdiff_t stride);
 } H264PredContext;
 
 void ff_h264_pred_init(H264PredContext *h, int codec_id,
diff --git a/libavcodec/h264pred_template.c b/libavcodec/h264pred_template.c
index 8e97d11104..e15c76c849 100644
--- a/libavcodec/h264pred_template.c
+++ b/libavcodec/h264pred_template.c
@@ -1131,7 +1131,7 @@ static void FUNCC(pred8x8l_horizontal_up)(uint8_t *_src, int has_topleft,
 #undef PL
 #undef SRC
 
-static void FUNCC(pred4x4_vertical_add)(uint8_t *_pix, const int16_t *_block,
+static void FUNCC(pred4x4_vertical_add)(uint8_t *_pix, int16_t *_block,
                                         ptrdiff_t stride)
 {
     int i;
@@ -1148,9 +1148,11 @@ static void FUNCC(pred4x4_vertical_add)(uint8_t *_pix, const int16_t *_block,
         pix++;
         block++;
     }
+
+    memset(_block, 0, sizeof(dctcoef) * 16);
 }
 
-static void FUNCC(pred4x4_horizontal_add)(uint8_t *_pix, const int16_t *_block,
+static void FUNCC(pred4x4_horizontal_add)(uint8_t *_pix, int16_t *_block,
                                           ptrdiff_t stride)
 {
     int i;
@@ -1166,9 +1168,11 @@ static void FUNCC(pred4x4_horizontal_add)(uint8_t *_pix, const int16_t *_block,
         pix+= stride;
         block+= 4;
     }
+
+    memset(_block, 0, sizeof(dctcoef) * 16);
 }
 
-static void FUNCC(pred8x8l_vertical_add)(uint8_t *_pix, const int16_t *_block,
+static void FUNCC(pred8x8l_vertical_add)(uint8_t *_pix, int16_t *_block,
                                          ptrdiff_t stride)
 {
     int i;
@@ -1189,9 +1193,11 @@ static void FUNCC(pred8x8l_vertical_add)(uint8_t *_pix, const int16_t *_block,
         pix++;
         block++;
     }
+
+    memset(_block, 0, sizeof(dctcoef) * 64);
 }
 
-static void FUNCC(pred8x8l_horizontal_add)(uint8_t *_pix, const int16_t *_block,
+static void FUNCC(pred8x8l_horizontal_add)(uint8_t *_pix, int16_t *_block,
                                            ptrdiff_t stride)
 {
     int i;
@@ -1211,10 +1217,12 @@ static void FUNCC(pred8x8l_horizontal_add)(uint8_t *_pix, const int16_t *_block,
         pix+= stride;
         block+= 8;
     }
+
+    memset(_block, 0, sizeof(dctcoef) * 64);
 }
 
 static void FUNCC(pred16x16_vertical_add)(uint8_t *pix, const int *block_offset,
-                                          const int16_t *block,
+                                          int16_t *block,
                                           ptrdiff_t stride)
 {
     int i;
@@ -1224,7 +1232,7 @@ static void FUNCC(pred16x16_vertical_add)(uint8_t *pix, const int *block_offset,
 
 static void FUNCC(pred16x16_horizontal_add)(uint8_t *pix,
                                             const int *block_offset,
-                                            const int16_t *block,
+                                            int16_t *block,
                                             ptrdiff_t stride)
 {
     int i;
@@ -1233,7 +1241,7 @@ static void FUNCC(pred16x16_horizontal_add)(uint8_t *pix,
 }
 
 static void FUNCC(pred8x8_vertical_add)(uint8_t *pix, const int *block_offset,
-                                        const int16_t *block, ptrdiff_t stride)
+                                        int16_t *block, ptrdiff_t stride)
 {
     int i;
     for(i=0; i<4; i++)
@@ -1241,7 +1249,7 @@ static void FUNCC(pred8x8_vertical_add)(uint8_t *pix, const int *block_offset,
 }
 
 static void FUNCC(pred8x16_vertical_add)(uint8_t *pix, const int *block_offset,
-                                         const int16_t *block, ptrdiff_t stride)
+                                         int16_t *block, ptrdiff_t stride)
 {
     int i;
     for(i=0; i<4; i++)
@@ -1251,7 +1259,7 @@ static void FUNCC(pred8x16_vertical_add)(uint8_t *pix, const int *block_offset,
 }
 
 static void FUNCC(pred8x8_horizontal_add)(uint8_t *pix, const int *block_offset,
-                                          const int16_t *block,
+                                          int16_t *block,
                                           ptrdiff_t stride)
 {
     int i;
@@ -1261,7 +1269,7 @@ static void FUNCC(pred8x8_horizontal_add)(uint8_t *pix, const int *block_offset,
 
 static void FUNCC(pred8x16_horizontal_add)(uint8_t *pix,
                                            const int *block_offset,
-                                           const int16_t *block, ptrdiff_t stride)
+                                           int16_t *block, ptrdiff_t stride)
 {
     int i;
     for(i=0; i<4; i++)
diff --git a/libavcodec/ppc/h264_altivec.c b/libavcodec/ppc/h264_altivec.c
index 59642fdc36..20549c5b6d 100644
--- a/libavcodec/ppc/h264_altivec.c
+++ b/libavcodec/ppc/h264_altivec.c
@@ -87,6 +87,7 @@ static void ff_h264_idct_add_altivec(uint8_t *dst, int16_t *block, int stride)
     vtmp1 = vec_sld(vtmp0, vtmp0, 8);
     vtmp2 = vec_ld(16,block);
     vtmp3 = vec_sld(vtmp2, vtmp2, 8);
+    memset(block, 0, 16 * sizeof(int16_t));
 
     VEC_1D_DCT(vtmp0,vtmp1,vtmp2,vtmp3,va0,va1,va2,va3);
     VEC_TRANSPOSE_4(va0,va1,va2,va3,vtmp0,vtmp1,vtmp2,vtmp3);
@@ -206,6 +207,7 @@ static void ff_h264_idct8_add_altivec( uint8_t *dst, int16_t *dct, int stride )
     s5 = vec_ld(0x50, (int16_t*)dct);
     s6 = vec_ld(0x60, (int16_t*)dct);
     s7 = vec_ld(0x70, (int16_t*)dct);
+    memset(dct, 0, 64 * sizeof(int16_t));
 
     IDCT8_1D_ALTIVEC(s0, s1, s2, s3, s4, s5, s6, s7,
                      d0, d1, d2, d3, d4, d5, d6, d7);
@@ -234,6 +236,7 @@ static av_always_inline void h264_idct_dc_add_internal(uint8_t *dst, int16_t *bl
     int i;
 
     dc = (block[0] + 32) >> 6;
+    block[0] = 0;
     dc16 = vec_splat((vec_s16) vec_lde(0, &dc), 1);
 
     if (size == 4)
diff --git a/libavcodec/svq3.c b/libavcodec/svq3.c
index 1ea99d15a6..0c3af86560 100644
--- a/libavcodec/svq3.c
+++ b/libavcodec/svq3.c
@@ -216,6 +216,8 @@ void ff_svq3_add_idct_c(uint8_t *dst, int16_t *block,
         dst[i + stride * 2] = av_clip_uint8(dst[i + stride * 2] + ((z1 - z2) * qmul + rr >> 20));
         dst[i + stride * 3] = av_clip_uint8(dst[i + stride * 3] + ((z0 - z3) * qmul + rr >> 20));
     }
+
+    memset(block, 0, 16 * sizeof(int16_t));
 }
 
 static inline int svq3_decode_block(GetBitContext *gb, int16_t *block,
@@ -664,8 +666,6 @@ static int svq3_decode_mb(SVQ3Context *s, unsigned int mb_type)
     }
     if (!IS_SKIP(mb_type) || h->pict_type == AV_PICTURE_TYPE_B) {
         memset(h->non_zero_count_cache + 8, 0, 14 * 8 * sizeof(uint8_t));
-        h->dsp.clear_blocks(h->mb +   0);
-        h->dsp.clear_blocks(h->mb + 384);
     }
 
     if (!IS_INTRA16x16(mb_type) &&
diff --git a/libavcodec/x86/h264_idct.asm b/libavcodec/x86/h264_idct.asm
index de0de24428..3ced8af40e 100644
--- a/libavcodec/x86/h264_idct.asm
+++ b/libavcodec/x86/h264_idct.asm
@@ -70,6 +70,10 @@ SECTION .text
     paddw        m0, m6
     IDCT4_1D      w, 0, 1, 2, 3, 4, 5
     pxor         m7, m7
+    movq    [%2+ 0], m7
+    movq    [%2+ 8], m7
+    movq    [%2+16], m7
+    movq    [%2+24], m7
 
     STORE_DIFFx2 m0, m1, m4, m5, m7, 6, %1, %3
     lea          %1, [%1+%3*2]
@@ -161,13 +165,31 @@ cglobal h264_idct_add_8, 3, 3, 0
 %endmacro
 
 ; %1=uint8_t *dst, %2=int16_t *block, %3=int stride
-%macro IDCT8_ADD_MMX_END 3
+%macro IDCT8_ADD_MMX_END 3-4
     IDCT8_1D_FULL %2
     mova    [%2   ], m5
     mova    [%2+16], m6
     mova    [%2+32], m7
 
     pxor         m7, m7
+%if %0 == 4
+    movq   [%4+  0], m7
+    movq   [%4+  8], m7
+    movq   [%4+ 16], m7
+    movq   [%4+ 24], m7
+    movq   [%4+ 32], m7
+    movq   [%4+ 40], m7
+    movq   [%4+ 48], m7
+    movq   [%4+ 56], m7
+    movq   [%4+ 64], m7
+    movq   [%4+ 72], m7
+    movq   [%4+ 80], m7
+    movq   [%4+ 88], m7
+    movq   [%4+ 96], m7
+    movq   [%4+104], m7
+    movq   [%4+112], m7
+    movq   [%4+120], m7
+%endif
     STORE_DIFFx2 m0, m1, m5, m6, m7, 6, %1, %3
     lea          %1, [%1+%3*2]
     STORE_DIFFx2 m2, m3, m5, m6, m7, 6, %1, %3
@@ -190,7 +212,7 @@ cglobal h264_idct8_add_8, 3, 4, 0
     IDCT8_ADD_MMX_START r1  , rsp
     IDCT8_ADD_MMX_START r1+8, rsp+64
     lea          r3, [r0+4]
-    IDCT8_ADD_MMX_END   r0  , rsp,   r2
+    IDCT8_ADD_MMX_END   r0  , rsp,   r2, r1
     IDCT8_ADD_MMX_END   r3  , rsp+8, r2
 
     ADD         rsp, pad
@@ -233,6 +255,14 @@ cglobal h264_idct8_add_8, 3, 4, 0
     SWAP          0, 8
     SWAP          1, 9
 %endif
+    mova   [%2+  0], m7
+    mova   [%2+ 16], m7
+    mova   [%2+ 32], m7
+    mova   [%2+ 48], m7
+    mova   [%2+ 64], m7
+    mova   [%2+ 80], m7
+    mova   [%2+ 96], m7
+    mova   [%2+112], m7
     lea          %1, [%1+%3*4]
     STORE_DIFF   m4, m6, m7, [%1     ]
     STORE_DIFF   m5, m6, m7, [%1+%3  ]
@@ -246,19 +276,11 @@ cglobal h264_idct8_add_8, 3, 4, 10
     IDCT8_ADD_SSE r0, r1, r2, r3
     RET
 
-%macro DC_ADD_MMXEXT_INIT 2-3
-%if %0 == 2
-    movsx        %1, word [%1]
+%macro DC_ADD_MMXEXT_INIT 2
     add          %1, 32
     sar          %1, 6
     movd         m0, %1d
     lea          %1, [%2*3]
-%else
-    add          %3, 32
-    sar          %3, 6
-    movd         m0, %3d
-    lea          %3, [%2*3]
-%endif
     pshufw       m0, m0, 0
     pxor         m1, m1
     psubw        m1, m0
@@ -287,18 +309,43 @@ cglobal h264_idct8_add_8, 3, 4, 10
 
 INIT_MMX mmxext
 ; ff_h264_idct_dc_add_mmxext(uint8_t *dst, int16_t *block, int stride)
-cglobal h264_idct_dc_add_8, 3, 3, 0
-    DC_ADD_MMXEXT_INIT r1, r2
-    DC_ADD_MMXEXT_OP movh, r0, r2, r1
+%if ARCH_X86_64
+cglobal h264_idct_dc_add_8, 3, 4, 0
+    movsx        r3, word [r1]
+    mov  dword [r1], 0
+    DC_ADD_MMXEXT_INIT r3, r2
+    DC_ADD_MMXEXT_OP movh, r0, r2, r3
     RET
 
 ; ff_h264_idct8_dc_add_mmxext(uint8_t *dst, int16_t *block, int stride)
-cglobal h264_idct8_dc_add_8, 3, 3, 0
-    DC_ADD_MMXEXT_INIT r1, r2
-    DC_ADD_MMXEXT_OP mova, r0, r2, r1
+cglobal h264_idct8_dc_add_8, 3, 4, 0
+    movsx        r3, word [r1]
+    mov  dword [r1], 0
+    DC_ADD_MMXEXT_INIT r3, r2
+    DC_ADD_MMXEXT_OP mova, r0, r2, r3
     lea          r0, [r0+r2*4]
-    DC_ADD_MMXEXT_OP mova, r0, r2, r1
+    DC_ADD_MMXEXT_OP mova, r0, r2, r3
     RET
+%else
+cglobal h264_idct_dc_add_8, 2, 3, 0
+    movsx        r2, word [r1]
+    mov  dword [r1], 0
+    mov          r1, r2m
+    DC_ADD_MMXEXT_INIT r2, r1
+    DC_ADD_MMXEXT_OP movh, r0, r1, r2
+    RET
+
+; ff_h264_idct8_dc_add_mmxext(uint8_t *dst, int16_t *block, int stride)
+cglobal h264_idct8_dc_add_8, 2, 3, 0
+    movsx        r2, word [r1]
+    mov  dword [r1], 0
+    mov          r1, r2m
+    DC_ADD_MMXEXT_INIT r2, r1
+    DC_ADD_MMXEXT_OP mova, r0, r1, r2
+    lea          r0, [r0+r1*4]
+    DC_ADD_MMXEXT_OP mova, r0, r1, r2
+    RET
+%endif
 
 INIT_MMX mmx
 ; ff_h264_idct_add16_mmx(uint8_t *dst, const int *block_offset,
@@ -343,7 +390,7 @@ cglobal h264_idct8_add4_8, 5, 7 + npicregs, 0, dst, block_offset, block, stride,
     add   word [r2], 32
     IDCT8_ADD_MMX_START r2  , rsp
     IDCT8_ADD_MMX_START r2+8, rsp+64
-    IDCT8_ADD_MMX_END   r6  , rsp,   r3
+    IDCT8_ADD_MMX_END   r6  , rsp,   r3, r2
     mov         r6d, dword [r1+r5*4]
     lea          r6, [r0+r6+4]
     IDCT8_ADD_MMX_END   r6  , rsp+8, r3
@@ -373,7 +420,8 @@ cglobal h264_idct_add16_8, 5, 8 + npicregs, 0, dst1, block_offset, block, stride
     movsx        r6, word [r2]
     test         r6, r6
     jz .no_dc
-    DC_ADD_MMXEXT_INIT r2, r3, r6
+    mov   word [r2], 0
+    DC_ADD_MMXEXT_INIT r6, r3
 %if ARCH_X86_64 == 0
 %define dst2q r1
 %define dst2d r1d
@@ -450,7 +498,8 @@ cglobal h264_idct_add16intra_8, 5, 8 + npicregs, 0, dst1, block_offset, block, s
     movsx        r6, word [r2]
     test         r6, r6
     jz .skipblock
-    DC_ADD_MMXEXT_INIT r2, r3, r6
+    mov   word [r2], 0
+    DC_ADD_MMXEXT_INIT r6, r3
 %if ARCH_X86_64 == 0
 %define dst2q r1
 %define dst2d r1d
@@ -489,7 +538,8 @@ cglobal h264_idct8_add4_8, 5, 8 + npicregs, 0, dst1, block_offset, block, stride
     movsx        r6, word [r2]
     test         r6, r6
     jz .no_dc
-    DC_ADD_MMXEXT_INIT r2, r3, r6
+    mov   word [r2], 0
+    DC_ADD_MMXEXT_INIT r6, r3
 %if ARCH_X86_64 == 0
 %define dst2q r1
 %define dst2d r1d
@@ -515,7 +565,7 @@ cglobal h264_idct8_add4_8, 5, 8 + npicregs, 0, dst1, block_offset, block, stride
     add   word [r2], 32
     IDCT8_ADD_MMX_START r2  , rsp
     IDCT8_ADD_MMX_START r2+8, rsp+64
-    IDCT8_ADD_MMX_END   r6  , rsp,   r3
+    IDCT8_ADD_MMX_END   r6  , rsp,   r3, r2
     mov         r6d, dword [r1+r5*4]
     lea          r6, [r0+r6+4]
     IDCT8_ADD_MMX_END   r6  , rsp+8, r3
@@ -547,7 +597,8 @@ cglobal h264_idct8_add4_8, 5, 8 + npicregs, 10, dst1, block_offset, block, strid
     test         r6, r6
     jz .no_dc
 INIT_MMX cpuname
-    DC_ADD_MMXEXT_INIT r2, r3, r6
+    mov   word [r2], 0
+    DC_ADD_MMXEXT_INIT r6, r3
 %if ARCH_X86_64 == 0
 %define dst2q r1
 %define dst2d r1d
@@ -650,7 +701,8 @@ h264_idct_add8_mmxext_plane:
     movsx        r6, word [r2]
     test         r6, r6
     jz .skipblock
-    DC_ADD_MMXEXT_INIT r2, r3, r6
+    mov   word [r2], 0
+    DC_ADD_MMXEXT_INIT r6, r3
 %if ARCH_X86_64
     mov         r0d, dword [r1+r5*4]
     add          r0, [dst2q]
@@ -693,7 +745,9 @@ cglobal h264_idct_add8_8, 5, 8 + npicregs, 0, dst1, block_offset, block, stride,
 ; r0 = uint8_t *dst, r2 = int16_t *block, r3 = int stride, r6=clobbered
 h264_idct_dc_add8_mmxext:
     movd         m0, [r2   ]          ;  0 0 X D
+    mov word [r2+ 0], 0
     punpcklwd    m0, [r2+32]          ;  x X d D
+    mov word [r2+32], 0
     paddsw       m0, [pw_32]
     psraw        m0, 6
     punpcklwd    m0, m0               ;  d d D D
@@ -723,6 +777,10 @@ h264_add8x4_idct_sse2:
     paddw m0, [pw_32]
     IDCT4_1D w,0,1,2,3,4,5
     pxor  m7, m7
+    mova [r2+ 0], m7
+    mova [r2+16], m7
+    mova [r2+32], m7
+    mova [r2+48], m7
     STORE_DIFFx2 m0, m1, m4, m5, m7, 6, r0, r3
     lea   r0, [r0+r3*2]
     STORE_DIFFx2 m2, m3, m4, m5, m7, 6, r0, r3
diff --git a/libavcodec/x86/h264_idct_10bit.asm b/libavcodec/x86/h264_idct_10bit.asm
index 51965f0f9f..4e51d2b5d0 100644
--- a/libavcodec/x86/h264_idct_10bit.asm
+++ b/libavcodec/x86/h264_idct_10bit.asm
@@ -66,6 +66,10 @@ SECTION .text
     paddd m0, [pd_32]
     IDCT4_1D d,0,1,2,3,4,5
     pxor  m5, m5
+    mova [%2+ 0], m5
+    mova [%2+16], m5
+    mova [%2+32], m5
+    mova [%2+48], m5
     STORE_DIFFx2 m0, m1, m4, m5, %1, %3
     lea   %1, [%1+%3*2]
     STORE_DIFFx2 m2, m3, m4, m5, %1, %3
@@ -98,6 +102,10 @@ add4x4_idct %+ SUFFIX:
     paddd m0, [pd_32]
     IDCT4_1D d,0,1,2,3,4,5
     pxor  m5, m5
+    mova  [r2+ 0], m5
+    mova  [r2+16], m5
+    mova  [r2+32], m5
+    mova  [r2+48], m5
     STORE_DIFFx2 m0, m1, m4, m5, r5, r3
     lea   r5, [r5+r3*2]
     STORE_DIFFx2 m2, m3, m4, m5, r5, r3
@@ -181,6 +189,7 @@ IDCT_ADD16_10
 INIT_MMX mmxext
 cglobal h264_idct_dc_add_10,3,3
     movd      m0, [r1]
+    mov dword [r1], 0
     paddd     m0, [pd_32]
     psrad     m0, 6
     lea       r1, [r2*3]
@@ -193,11 +202,11 @@ cglobal h264_idct_dc_add_10,3,3
 ; void h264_idct8_dc_add(pixel *dst, dctcoef *block, int stride)
 ;-----------------------------------------------------------------------------
 %macro IDCT8_DC_ADD 0
-cglobal h264_idct8_dc_add_10,3,3,7
-    mov      r1d, [r1]
-    add       r1, 32
-    sar       r1, 6
-    movd      m0, r1d
+cglobal h264_idct8_dc_add_10,3,4,7
+    movd      m0, [r1]
+    mov dword[r1], 0
+    paddd     m0, [pd_32]
+    psrad     m0, 6
     lea       r1, [r2*3]
     SPLATW    m0, m0, 0
     mova      m6, [pw_pixel_max]
@@ -247,6 +256,8 @@ idct_dc_add %+ SUFFIX:
     add       r5, r0
     movq      m0, [r2+ 0]
     movhps    m0, [r2+64]
+    mov dword [r2+ 0], 0
+    mov dword [r2+64], 0
     paddd     m0, [pd_32]
     psrad     m0, 6
     pshufhw   m0, m0, 0
@@ -461,6 +472,22 @@ h264_idct8_add1_10 %+ SUFFIX:
     packssdw      m8, m0
     paddsw        m8, [r0]
     pxor          m0, m0
+    mova    [r1+  0], m0
+    mova    [r1+ 16], m0
+    mova    [r1+ 32], m0
+    mova    [r1+ 48], m0
+    mova    [r1+ 64], m0
+    mova    [r1+ 80], m0
+    mova    [r1+ 96], m0
+    mova    [r1+112], m0
+    mova    [r1+128], m0
+    mova    [r1+144], m0
+    mova    [r1+160], m0
+    mova    [r1+176], m0
+    mova    [r1+192], m0
+    mova    [r1+208], m0
+    mova    [r1+224], m0
+    mova    [r1+240], m0
     CLIPW         m8, m0, [pw_pixel_max]
     mova        [r0], m8
     mova          m8, [pw_pixel_max]
@@ -480,6 +507,22 @@ h264_idct8_add1_10 %+ SUFFIX:
     lea           r3, [r0+8]
     IDCT8_ADD_SSE_END r0, rsp,    r2
     IDCT8_ADD_SSE_END r3, rsp+16, r2
+    mova    [r1+  0], m7
+    mova    [r1+ 16], m7
+    mova    [r1+ 32], m7
+    mova    [r1+ 48], m7
+    mova    [r1+ 64], m7
+    mova    [r1+ 80], m7
+    mova    [r1+ 96], m7
+    mova    [r1+112], m7
+    mova    [r1+128], m7
+    mova    [r1+144], m7
+    mova    [r1+160], m7
+    mova    [r1+176], m7
+    mova    [r1+192], m7
+    mova    [r1+208], m7
+    mova    [r1+224], m7
+    mova    [r1+240], m7
 %endif ; ARCH_X86_64
 
     add          rsp, pad