diff --git a/libavcodec/arm/vp3dsp_neon.S b/libavcodec/arm/vp3dsp_neon.S
index 0c88562b45..f133905efe 100644
--- a/libavcodec/arm/vp3dsp_neon.S
+++ b/libavcodec/arm/vp3dsp_neon.S
@@ -108,14 +108,20 @@ endfunc
 
 function vp3_idct_start_neon
     vpush           {d8-d15}
+    vmov.i16        q4,  #0
+    vmov.i16        q5,  #0
     movrel          r3,  vp3_idct_constants
     vld1.64         {d0-d1},   [r3,:128]
-    vld1.64         {d16-d19}, [r2,:128]!
-    vld1.64         {d20-d23}, [r2,:128]!
-    vld1.64         {d24-d27}, [r2,:128]!
+    vld1.64         {d16-d19}, [r2,:128]
+    vst1.64         {q4-q5},   [r2,:128]!
+    vld1.64         {d20-d23}, [r2,:128]
+    vst1.64         {q4-q5},   [r2,:128]!
+    vld1.64         {d24-d27}, [r2,:128]
+    vst1.64         {q4-q5},   [r2,:128]!
     vadd.s16        q1,  q8,  q12
     vsub.s16        q8,  q8,  q12
-    vld1.64         {d28-d31}, [r2,:128]!
+    vld1.64         {d28-d31}, [r2,:128]
+    vst1.64         {q4-q5},   [r2,:128]!
 
 vp3_idct_core_neon:
     vmull.s16       q2,  d18, xC1S7     // (ip[1] * C1) << 16
@@ -345,10 +351,12 @@ function ff_vp3_idct_add_neon, export=1
 endfunc
 
 function ff_vp3_idct_dc_add_neon, export=1
-    ldrsh           r2,  [r2]
+    ldrsh           r12, [r2]
     mov             r3,  r0
-    add             r2,  r2,  #15
-    vdup.16         q15, r2
+    add             r12, r12,  #15
+    vdup.16         q15, r12
+    mov             r12, 0
+    strh            r12, [r2]
     vshr.s16        q15, q15, #5
 
     vld1.8          {d0}, [r0,:64], r1
diff --git a/libavcodec/mpegvideo.c b/libavcodec/mpegvideo.c
index d4d913b053..a21054b5ff 100644
--- a/libavcodec/mpegvideo.c
+++ b/libavcodec/mpegvideo.c
@@ -1666,7 +1666,7 @@ static void draw_line(uint8_t *buf, int sx, int sy, int ex, int ey,
         buf += sx + sy * stride;
         ex  -= sx;
         f    = ((ey - sy) << 16) / ex;
-        for(x= 0; x <= ex; x++){
+        for (x = 0; x <= ex; x++) {
             y  = (x * f) >> 16;
             fr = (x * f) & 0xFFFF;
             buf[y * stride + x]       += (color * (0x10000 - fr)) >> 16;
diff --git a/libavcodec/ppc/vp3dsp_altivec.c b/libavcodec/ppc/vp3dsp_altivec.c
index ac00c933bb..b3581ab708 100644
--- a/libavcodec/ppc/vp3dsp_altivec.c
+++ b/libavcodec/ppc/vp3dsp_altivec.c
@@ -140,6 +140,7 @@ static void vp3_idct_put_altivec(uint8_t *dst, int stride, DCTELEM block[64])
     PUT(b5)     dst += stride;
     PUT(b6)     dst += stride;
     PUT(b7)
+    memset(block, 0, sizeof(*block) * 64);
 }
 
 static void vp3_idct_add_altivec(uint8_t *dst, int stride, DCTELEM block[64])
@@ -171,6 +172,7 @@ static void vp3_idct_add_altivec(uint8_t *dst, int stride, DCTELEM block[64])
     ADD(b5)     dst += stride;
     ADD(b6)     dst += stride;
     ADD(b7)
+    memset(block, 0, sizeof(*block) * 64);
 }
 
 #endif /* HAVE_ALTIVEC */
diff --git a/libavcodec/vp3.c b/libavcodec/vp3.c
index ce3ffe832a..62416172de 100644
--- a/libavcodec/vp3.c
+++ b/libavcodec/vp3.c
@@ -138,6 +138,7 @@ typedef struct Vp3DecodeContext {
     DSPContext dsp;
     VideoDSPContext vdsp;
     VP3DSPContext vp3dsp;
+    DECLARE_ALIGNED(16, DCTELEM, block)[64];
     int flipped_image;
     int last_slice_end;
     int skip_loop_filter;
@@ -1458,7 +1459,7 @@ static void await_reference_row(Vp3DecodeContext *s, Vp3Fragment *fragment, int
 static void render_slice(Vp3DecodeContext *s, int slice)
 {
     int x, y, i, j, fragment;
-    LOCAL_ALIGNED_16(DCTELEM, block, [64]);
+    DCTELEM *block = s->block;
     int motion_x = 0xdeadbeef, motion_y = 0xdeadbeef;
     int motion_halfpel_index;
     uint8_t *motion_source;
@@ -1571,8 +1572,6 @@ static void render_slice(Vp3DecodeContext *s, int slice)
                         }
                     }
 
-                        s->dsp.clear_block(block);
-
                     /* invert DCT and place (or add) in final output */
 
                     if (s->all_fragments[i].coding_method == MODE_INTRA) {
diff --git a/libavcodec/vp3dsp.c b/libavcodec/vp3dsp.c
index 0e0c0f58ae..6502a158e6 100644
--- a/libavcodec/vp3dsp.c
+++ b/libavcodec/vp3dsp.c
@@ -215,14 +215,16 @@ static av_always_inline void idct(uint8_t *dst, int stride, int16_t *input, int
 
 static void vp3_idct_put_c(uint8_t *dest/*align 8*/, int line_size, DCTELEM *block/*align 16*/){
     idct(dest, line_size, block, 1);
+    memset(block, 0, sizeof(*block) * 64);
 }
 
 static void vp3_idct_add_c(uint8_t *dest/*align 8*/, int line_size, DCTELEM *block/*align 16*/){
     idct(dest, line_size, block, 2);
+    memset(block, 0, sizeof(*block) * 64);
 }
 
 static void vp3_idct_dc_add_c(uint8_t *dest/*align 8*/, int line_size,
-                              const DCTELEM *block/*align 16*/){
+                              DCTELEM *block/*align 16*/){
     int i, dc = (block[0] + 15) >> 5;
 
     for(i = 0; i < 8; i++){
@@ -236,6 +238,7 @@ static void vp3_idct_dc_add_c(uint8_t *dest/*align 8*/, int line_size,
         dest[7] = av_clip_uint8(dest[7] + dc);
         dest += line_size;
     }
+    block[0] = 0;
 }
 
 static void vp3_v_loop_filter_c(uint8_t *first_pixel, int stride,
diff --git a/libavcodec/vp3dsp.h b/libavcodec/vp3dsp.h
index a14dec1eb4..bc651997d2 100644
--- a/libavcodec/vp3dsp.h
+++ b/libavcodec/vp3dsp.h
@@ -25,7 +25,7 @@
 typedef struct VP3DSPContext {
     void (*idct_put)(uint8_t *dest, int line_size, DCTELEM *block);
     void (*idct_add)(uint8_t *dest, int line_size, DCTELEM *block);
-    void (*idct_dc_add)(uint8_t *dest, int line_size, const DCTELEM *block);
+    void (*idct_dc_add)(uint8_t *dest, int line_size, DCTELEM *block);
     void (*v_loop_filter)(uint8_t *src, int stride, int *bounding_values);
     void (*h_loop_filter)(uint8_t *src, int stride, int *bounding_values);
 
diff --git a/libavcodec/x86/vp3dsp.asm b/libavcodec/x86/vp3dsp.asm
index 3a5ed03c64..be5f21b2d8 100644
--- a/libavcodec/x86/vp3dsp.asm
+++ b/libavcodec/x86/vp3dsp.asm
@@ -561,6 +561,13 @@ cglobal vp3_idct_put, 3, 4, 9
     movhps [r0+r3  ], m3
 %endif
 %assign %%i %%i+64
+%endrep
+
+    pxor          m0, m0
+%assign %%offset 0
+%rep 128/mmsize
+    mova [r2+%%offset], m0
+%assign %%offset %%offset+mmsize
 %endrep
     RET
 
@@ -600,6 +607,11 @@ cglobal vp3_idct_add, 3, 4, 9
     movhps   [r0+r1], m0
 %endif
     lea           r0, [r0+r1*2]
+%assign %%offset 0
+%rep 32/mmsize
+    mova [r2+%%offset], m4
+%assign %%offset %%offset+mmsize
+%endrep
     add           r2, 32
     dec           r3
     jg .loop
@@ -620,7 +632,7 @@ vp3_idct_funcs
     paddusb       m2, m0
     movq          m4, [r0+r1*2]
     paddusb       m3, m0
-    movq          m5, [r0+r3  ]
+    movq          m5, [r0+r2  ]
     paddusb       m4, m0
     paddusb       m5, m0
     psubusb       m2, m1
@@ -630,7 +642,7 @@ vp3_idct_funcs
     movq   [r0+r1  ], m3
     psubusb       m5, m1
     movq   [r0+r1*2], m4
-    movq   [r0+r3  ], m5
+    movq   [r0+r2  ], m5
 %endmacro
 
 INIT_MMX mmxext
@@ -638,11 +650,12 @@ cglobal vp3_idct_dc_add, 3, 4
 %if ARCH_X86_64
     movsxd        r1, r1d
 %endif
-    lea           r3, [r1*3]
-    movsx         r2, word [r2]
-    add           r2, 15
-    sar           r2, 5
-    movd          m0, r2d
+    movsx         r3, word [r2]
+    mov    word [r2], 0
+    lea           r2, [r1*3]
+    add           r3, 15
+    sar           r3, 5
+    movd          m0, r3d
     pshufw        m0, m0, 0x0
     pxor          m1, m1
     psubw         m1, m0
diff --git a/libavcodec/x86/vp3dsp_init.c b/libavcodec/x86/vp3dsp_init.c
index eddfd07265..245b60f6fa 100644
--- a/libavcodec/x86/vp3dsp_init.c
+++ b/libavcodec/x86/vp3dsp_init.c
@@ -32,7 +32,7 @@ void ff_vp3_idct_put_sse2(uint8_t *dest, int line_size, DCTELEM *block);
 void ff_vp3_idct_add_sse2(uint8_t *dest, int line_size, DCTELEM *block);
 
 void ff_vp3_idct_dc_add_mmxext(uint8_t *dest, int line_size,
-                               const DCTELEM *block);
+                               DCTELEM *block);
 
 void ff_vp3_v_loop_filter_mmxext(uint8_t *src, int stride,
                                  int *bounding_values);