diff --git a/libavcodec/aarch64/me_cmp_init_aarch64.c b/libavcodec/aarch64/me_cmp_init_aarch64.c
index 136b008eb7..79c739914f 100644
--- a/libavcodec/aarch64/me_cmp_init_aarch64.c
+++ b/libavcodec/aarch64/me_cmp_init_aarch64.c
@@ -23,11 +23,11 @@
 #include "libavutil/aarch64/cpu.h"
 #include "libavcodec/mpegvideo.h"
 
-int ff_pix_abs16_neon(MpegEncContext *s, uint8_t *blk1, uint8_t *blk2,
+int ff_pix_abs16_neon(MpegEncContext *s, const uint8_t *blk1, const uint8_t *blk2,
                       ptrdiff_t stride, int h);
-int ff_pix_abs16_xy2_neon(MpegEncContext *s, uint8_t *blk1, uint8_t *blk2,
+int ff_pix_abs16_xy2_neon(MpegEncContext *s, const uint8_t *blk1, const uint8_t *blk2,
                       ptrdiff_t stride, int h);
-int ff_pix_abs16_x2_neon(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs16_x2_neon(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                       ptrdiff_t stride, int h);
 
 av_cold void ff_me_cmp_init_aarch64(MECmpContext *c, AVCodecContext *avctx)
diff --git a/libavcodec/alpha/me_cmp_alpha.c b/libavcodec/alpha/me_cmp_alpha.c
index 8f360190f4..4e9e0f88dc 100644
--- a/libavcodec/alpha/me_cmp_alpha.c
+++ b/libavcodec/alpha/me_cmp_alpha.c
@@ -23,7 +23,7 @@
 #include "libavcodec/me_cmp.h"
 #include "asm.h"
 
-int pix_abs16x16_mvi_asm(void *v, uint8_t *pix1, uint8_t *pix2, int line_size, int h);
+int pix_abs16x16_mvi_asm(void *v, const uint8_t *pix1, const uint8_t *pix2, int line_size, int h);
 
 static inline uint64_t avg2(uint64_t a, uint64_t b)
 {
@@ -44,7 +44,7 @@ static inline uint64_t avg4(uint64_t l1, uint64_t l2, uint64_t l3, uint64_t l4)
     return r1 + r2;
 }
 
-static int pix_abs8x8_mvi(void *v, uint8_t *pix1, uint8_t *pix2, int line_size, int h)
+static int pix_abs8x8_mvi(void *v, const uint8_t *pix1, const uint8_t *pix2, int line_size, int h)
 {
     int result = 0;
 
@@ -77,7 +77,7 @@ static int pix_abs8x8_mvi(void *v, uint8_t *pix1, uint8_t *pix2, int line_size,
 }
 
 #if 0                           /* now done in assembly */
-int pix_abs16x16_mvi(uint8_t *pix1, uint8_t *pix2, int line_size)
+int pix_abs16x16_mvi(const uint8_t *pix1, const uint8_t *pix2, int line_size)
 {
     int result = 0;
     int h = 16;
@@ -119,7 +119,7 @@ int pix_abs16x16_mvi(uint8_t *pix1, uint8_t *pix2, int line_size)
 }
 #endif
 
-static int pix_abs16x16_x2_mvi(void *v, uint8_t *pix1, uint8_t *pix2, int line_size, int h)
+static int pix_abs16x16_x2_mvi(void *v, const uint8_t *pix1, const uint8_t *pix2, int line_size, int h)
 {
     int result = 0;
     uint64_t disalign = (size_t) pix2 & 0x7;
@@ -192,7 +192,7 @@ static int pix_abs16x16_x2_mvi(void *v, uint8_t *pix1, uint8_t *pix2, int line_s
     return result;
 }
 
-static int pix_abs16x16_y2_mvi(void *v, uint8_t *pix1, uint8_t *pix2, int line_size, int h)
+static int pix_abs16x16_y2_mvi(void *v, const uint8_t *pix1, const uint8_t *pix2, int line_size, int h)
 {
     int result = 0;
 
@@ -245,7 +245,7 @@ static int pix_abs16x16_y2_mvi(void *v, uint8_t *pix1, uint8_t *pix2, int line_s
     return result;
 }
 
-static int pix_abs16x16_xy2_mvi(void *v, uint8_t *pix1, uint8_t *pix2, int line_size, int h)
+static int pix_abs16x16_xy2_mvi(void *v, const uint8_t *pix1, const uint8_t *pix2, int line_size, int h)
 {
     int result = 0;
 
diff --git a/libavcodec/alpha/me_cmp_mvi_asm.S b/libavcodec/alpha/me_cmp_mvi_asm.S
index 2399085bcb..183feeb40c 100644
--- a/libavcodec/alpha/me_cmp_mvi_asm.S
+++ b/libavcodec/alpha/me_cmp_mvi_asm.S
@@ -38,7 +38,7 @@
         .text
 
 /*****************************************************************************
- * int pix_abs16x16_mvi_asm(uint8_t *pix1, uint8_t *pix2, int line_size)
+ * int pix_abs16x16_mvi_asm(const uint8_t *pix1, const uint8_t *pix2, int line_size)
  *
  * This code is written with a pca56 in mind. For ev6, one should
  * really take the increased latency of 3 cycles for MVI instructions
diff --git a/libavcodec/arm/me_cmp_init_arm.c b/libavcodec/arm/me_cmp_init_arm.c
index 03870a2bfa..8c556f1755 100644
--- a/libavcodec/arm/me_cmp_init_arm.c
+++ b/libavcodec/arm/me_cmp_init_arm.c
@@ -25,17 +25,17 @@
 #include "libavcodec/me_cmp.h"
 #include "libavcodec/mpegvideo.h"
 
-int ff_pix_abs16_armv6(MpegEncContext *s, uint8_t *blk1, uint8_t *blk2,
+int ff_pix_abs16_armv6(MpegEncContext *s, const uint8_t *blk1, const uint8_t *blk2,
                        ptrdiff_t stride, int h);
-int ff_pix_abs16_x2_armv6(MpegEncContext *s, uint8_t *blk1, uint8_t *blk2,
+int ff_pix_abs16_x2_armv6(MpegEncContext *s, const uint8_t *blk1, const uint8_t *blk2,
                           ptrdiff_t stride, int h);
-int ff_pix_abs16_y2_armv6(MpegEncContext *s, uint8_t *blk1, uint8_t *blk2,
+int ff_pix_abs16_y2_armv6(MpegEncContext *s, const uint8_t *blk1, const uint8_t *blk2,
                           ptrdiff_t stride, int h);
 
-int ff_pix_abs8_armv6(MpegEncContext *s, uint8_t *blk1, uint8_t *blk2,
+int ff_pix_abs8_armv6(MpegEncContext *s, const uint8_t *blk1, const uint8_t *blk2,
                       ptrdiff_t stride, int h);
 
-int ff_sse16_armv6(MpegEncContext *s, uint8_t *blk1, uint8_t *blk2,
+int ff_sse16_armv6(MpegEncContext *s, const uint8_t *blk1, const uint8_t *blk2,
                    ptrdiff_t stride, int h);
 
 av_cold void ff_me_cmp_init_arm(MECmpContext *c, AVCodecContext *avctx)
diff --git a/libavcodec/me_cmp.c b/libavcodec/me_cmp.c
index d0cd14ad33..fa82ae54ae 100644
--- a/libavcodec/me_cmp.c
+++ b/libavcodec/me_cmp.c
@@ -67,7 +67,7 @@ const uint32_t ff_square_tab[512] = {
     57600, 58081, 58564, 59049, 59536, 60025, 60516, 61009, 61504, 62001, 62500, 63001, 63504, 64009, 64516, 65025,
 };
 
-static int sse4_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int sse4_c(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                   ptrdiff_t stride, int h)
 {
     int s = 0, i;
@@ -84,7 +84,7 @@ static int sse4_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static int sse8_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int sse8_c(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                   ptrdiff_t stride, int h)
 {
     int s = 0, i;
@@ -105,7 +105,7 @@ static int sse8_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static int sse16_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int sse16_c(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                    ptrdiff_t stride, int h)
 {
     int s = 0, i;
@@ -135,7 +135,7 @@ static int sse16_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static int sum_abs_dctelem_c(int16_t *block)
+static int sum_abs_dctelem_c(const int16_t *block)
 {
     int sum = 0, i;
 
@@ -147,7 +147,7 @@ static int sum_abs_dctelem_c(int16_t *block)
 #define avg2(a, b) (((a) + (b) + 1) >> 1)
 #define avg4(a, b, c, d) (((a) + (b) + (c) + (d) + 2) >> 2)
 
-static inline int pix_abs16_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static inline int pix_abs16_c(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                               ptrdiff_t stride, int h)
 {
     int s = 0, i;
@@ -175,7 +175,7 @@ static inline int pix_abs16_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static inline int pix_median_abs16_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static inline int pix_median_abs16_c(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                              ptrdiff_t stride, int h)
 {
     int s = 0, i, j;
@@ -214,7 +214,7 @@ static inline int pix_median_abs16_c(MpegEncContext *v, uint8_t *pix1, uint8_t *
     return s;
 }
 
-static int pix_abs16_x2_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int pix_abs16_x2_c(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                           ptrdiff_t stride, int h)
 {
     int s = 0, i;
@@ -242,11 +242,11 @@ static int pix_abs16_x2_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static int pix_abs16_y2_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int pix_abs16_y2_c(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                           ptrdiff_t stride, int h)
 {
     int s = 0, i;
-    uint8_t *pix3 = pix2 + stride;
+    const uint8_t *pix3 = pix2 + stride;
 
     for (i = 0; i < h; i++) {
         s    += abs(pix1[0]  - avg2(pix2[0],  pix3[0]));
@@ -272,11 +272,11 @@ static int pix_abs16_y2_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static int pix_abs16_xy2_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int pix_abs16_xy2_c(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                            ptrdiff_t stride, int h)
 {
     int s = 0, i;
-    uint8_t *pix3 = pix2 + stride;
+    const uint8_t *pix3 = pix2 + stride;
 
     for (i = 0; i < h; i++) {
         s    += abs(pix1[0]  - avg4(pix2[0],  pix2[1],  pix3[0],  pix3[1]));
@@ -302,7 +302,7 @@ static int pix_abs16_xy2_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static inline int pix_abs8_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static inline int pix_abs8_c(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                              ptrdiff_t stride, int h)
 {
     int s = 0, i;
@@ -322,7 +322,7 @@ static inline int pix_abs8_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static inline int pix_median_abs8_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static inline int pix_median_abs8_c(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                              ptrdiff_t stride, int h)
 {
     int s = 0, i, j;
@@ -353,7 +353,7 @@ static inline int pix_median_abs8_c(MpegEncContext *v, uint8_t *pix1, uint8_t *p
     return s;
 }
 
-static int pix_abs8_x2_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int pix_abs8_x2_c(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                          ptrdiff_t stride, int h)
 {
     int s = 0, i;
@@ -373,11 +373,11 @@ static int pix_abs8_x2_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static int pix_abs8_y2_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int pix_abs8_y2_c(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                          ptrdiff_t stride, int h)
 {
     int s = 0, i;
-    uint8_t *pix3 = pix2 + stride;
+    const uint8_t *pix3 = pix2 + stride;
 
     for (i = 0; i < h; i++) {
         s    += abs(pix1[0] - avg2(pix2[0], pix3[0]));
@@ -395,11 +395,11 @@ static int pix_abs8_y2_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static int pix_abs8_xy2_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int pix_abs8_xy2_c(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                           ptrdiff_t stride, int h)
 {
     int s = 0, i;
-    uint8_t *pix3 = pix2 + stride;
+    const uint8_t *pix3 = pix2 + stride;
 
     for (i = 0; i < h; i++) {
         s    += abs(pix1[0] - avg4(pix2[0], pix2[1], pix3[0], pix3[1]));
@@ -417,7 +417,7 @@ static int pix_abs8_xy2_c(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static int nsse16_c(MpegEncContext *c, uint8_t *s1, uint8_t *s2,
+static int nsse16_c(MpegEncContext *c, const uint8_t *s1, const uint8_t *s2,
                     ptrdiff_t stride, int h)
 {
     int score1 = 0, score2 = 0, x, y;
@@ -442,7 +442,7 @@ static int nsse16_c(MpegEncContext *c, uint8_t *s1, uint8_t *s2,
         return score1 + FFABS(score2) * 8;
 }
 
-static int nsse8_c(MpegEncContext *c, uint8_t *s1, uint8_t *s2,
+static int nsse8_c(MpegEncContext *c, const uint8_t *s1, const uint8_t *s2,
                    ptrdiff_t stride, int h)
 {
     int score1 = 0, score2 = 0, x, y;
@@ -467,7 +467,7 @@ static int nsse8_c(MpegEncContext *c, uint8_t *s1, uint8_t *s2,
         return score1 + FFABS(score2) * 8;
 }
 
-static int zero_cmp(MpegEncContext *s, uint8_t *a, uint8_t *b,
+static int zero_cmp(MpegEncContext *s, const uint8_t *a, const uint8_t *b,
                     ptrdiff_t stride, int h)
 {
     return 0;
@@ -553,8 +553,8 @@ void ff_set_cmp(MECmpContext *c, me_cmp_func *cmp, int type)
 
 #define BUTTERFLYA(x, y) (FFABS((x) + (y)) + FFABS((x) - (y)))
 
-static int hadamard8_diff8x8_c(MpegEncContext *s, uint8_t *dst,
-                               uint8_t *src, ptrdiff_t stride, int h)
+static int hadamard8_diff8x8_c(MpegEncContext *s, const uint8_t *dst,
+                               const uint8_t *src, ptrdiff_t stride, int h)
 {
     int i, temp[64], sum = 0;
 
@@ -605,8 +605,8 @@ static int hadamard8_diff8x8_c(MpegEncContext *s, uint8_t *dst,
     return sum;
 }
 
-static int hadamard8_intra8x8_c(MpegEncContext *s, uint8_t *src,
-                                uint8_t *dummy, ptrdiff_t stride, int h)
+static int hadamard8_intra8x8_c(MpegEncContext *s, const uint8_t *src,
+                                const uint8_t *dummy, ptrdiff_t stride, int h)
 {
     int i, temp[64], sum = 0;
 
@@ -657,8 +657,8 @@ static int hadamard8_intra8x8_c(MpegEncContext *s, uint8_t *src,
     return sum;
 }
 
-static int dct_sad8x8_c(MpegEncContext *s, uint8_t *src1,
-                        uint8_t *src2, ptrdiff_t stride, int h)
+static int dct_sad8x8_c(MpegEncContext *s, const uint8_t *src1,
+                        const uint8_t *src2, ptrdiff_t stride, int h)
 {
     LOCAL_ALIGNED_16(int16_t, temp, [64]);
 
@@ -698,8 +698,8 @@ static int dct_sad8x8_c(MpegEncContext *s, uint8_t *src1,
         DST(7, (a4 >> 2) - a7);                         \
     }
 
-static int dct264_sad8x8_c(MpegEncContext *s, uint8_t *src1,
-                           uint8_t *src2, ptrdiff_t stride, int h)
+static int dct264_sad8x8_c(MpegEncContext *s, const uint8_t *src1,
+                           const uint8_t *src2, ptrdiff_t stride, int h)
 {
     int16_t dct[8][8];
     int i, sum = 0;
@@ -723,8 +723,8 @@ static int dct264_sad8x8_c(MpegEncContext *s, uint8_t *src1,
 }
 #endif
 
-static int dct_max8x8_c(MpegEncContext *s, uint8_t *src1,
-                        uint8_t *src2, ptrdiff_t stride, int h)
+static int dct_max8x8_c(MpegEncContext *s, const uint8_t *src1,
+                        const uint8_t *src2, ptrdiff_t stride, int h)
 {
     LOCAL_ALIGNED_16(int16_t, temp, [64]);
     int sum = 0, i;
@@ -740,8 +740,8 @@ static int dct_max8x8_c(MpegEncContext *s, uint8_t *src1,
     return sum;
 }
 
-static int quant_psnr8x8_c(MpegEncContext *s, uint8_t *src1,
-                           uint8_t *src2, ptrdiff_t stride, int h)
+static int quant_psnr8x8_c(MpegEncContext *s, const uint8_t *src1,
+                           const uint8_t *src2, ptrdiff_t stride, int h)
 {
     LOCAL_ALIGNED_16(int16_t, temp, [64 * 2]);
     int16_t *const bak = temp + 64;
@@ -765,7 +765,7 @@ static int quant_psnr8x8_c(MpegEncContext *s, uint8_t *src1,
     return sum;
 }
 
-static int rd8x8_c(MpegEncContext *s, uint8_t *src1, uint8_t *src2,
+static int rd8x8_c(MpegEncContext *s, const uint8_t *src1, const uint8_t *src2,
                    ptrdiff_t stride, int h)
 {
     const uint8_t *scantable = s->intra_scantable.permutated;
@@ -842,7 +842,7 @@ static int rd8x8_c(MpegEncContext *s, uint8_t *src1, uint8_t *src2,
     return distortion + ((bits * s->qscale * s->qscale * 109 + 64) >> 7);
 }
 
-static int bit8x8_c(MpegEncContext *s, uint8_t *src1, uint8_t *src2,
+static int bit8x8_c(MpegEncContext *s, const uint8_t *src1, const uint8_t *src2,
                     ptrdiff_t stride, int h)
 {
     const uint8_t *scantable = s->intra_scantable.permutated;
@@ -905,7 +905,7 @@ static int bit8x8_c(MpegEncContext *s, uint8_t *src1, uint8_t *src2,
 
 #define VSAD_INTRA(size)                                                \
 static int vsad_intra ## size ## _c(MpegEncContext *c,                  \
-                                    uint8_t *s, uint8_t *dummy,         \
+                                    const uint8_t *s, const uint8_t *dummy, \
                                     ptrdiff_t stride, int h)            \
 {                                                                       \
     int score = 0, x, y;                                                \
@@ -927,7 +927,7 @@ VSAD_INTRA(16)
 
 #define VSAD(size)                                                             \
 static int vsad ## size ## _c(MpegEncContext *c,                               \
-                              uint8_t *s1, uint8_t *s2,                        \
+                              const uint8_t *s1, const uint8_t *s2,            \
                               ptrdiff_t stride, int h)                               \
 {                                                                              \
     int score = 0, x, y;                                                       \
@@ -947,7 +947,7 @@ VSAD(16)
 #define SQ(a) ((a) * (a))
 #define VSSE_INTRA(size)                                                \
 static int vsse_intra ## size ## _c(MpegEncContext *c,                  \
-                                    uint8_t *s, uint8_t *dummy,         \
+                                    const uint8_t *s, const uint8_t *dummy, \
                                     ptrdiff_t stride, int h)            \
 {                                                                       \
     int score = 0, x, y;                                                \
@@ -968,7 +968,7 @@ VSSE_INTRA(8)
 VSSE_INTRA(16)
 
 #define VSSE(size)                                                             \
-static int vsse ## size ## _c(MpegEncContext *c, uint8_t *s1, uint8_t *s2,     \
+static int vsse ## size ## _c(MpegEncContext *c, const uint8_t *s1, const uint8_t *s2, \
                               ptrdiff_t stride, int h)                         \
 {                                                                              \
     int score = 0, x, y;                                                       \
@@ -986,7 +986,7 @@ VSSE(8)
 VSSE(16)
 
 #define WRAPPER8_16_SQ(name8, name16)                                   \
-static int name16(MpegEncContext *s, uint8_t *dst, uint8_t *src,        \
+static int name16(MpegEncContext *s, const uint8_t *dst, const uint8_t *src, \
                   ptrdiff_t stride, int h)                              \
 {                                                                       \
     int score = 0;                                                      \
diff --git a/libavcodec/me_cmp.h b/libavcodec/me_cmp.h
index 7b057a923b..c6de2d0061 100644
--- a/libavcodec/me_cmp.h
+++ b/libavcodec/me_cmp.h
@@ -46,12 +46,12 @@ struct MpegEncContext;
  * Although currently h < 4 is not used as functions with
  * width < 8 are neither used nor implemented. */
 typedef int (*me_cmp_func)(struct MpegEncContext *c,
-                           uint8_t *blk1 /* align width (8 or 16) */,
-                           uint8_t *blk2 /* align 1 */, ptrdiff_t stride,
+                           const uint8_t *blk1 /* align width (8 or 16) */,
+                           const uint8_t *blk2 /* align 1 */, ptrdiff_t stride,
                            int h);
 
 typedef struct MECmpContext {
-    int (*sum_abs_dctelem)(int16_t *block /* align 16 */);
+    int (*sum_abs_dctelem)(const int16_t *block /* align 16 */);
 
     me_cmp_func sad[6]; /* identical to pix_absAxA except additional void * */
     me_cmp_func sse[6];
diff --git a/libavcodec/mips/me_cmp_mips.h b/libavcodec/mips/me_cmp_mips.h
index e0d0f51af8..728640102a 100644
--- a/libavcodec/mips/me_cmp_mips.h
+++ b/libavcodec/mips/me_cmp_mips.h
@@ -24,37 +24,37 @@
 #include "../mpegvideo.h"
 #include "libavcodec/bit_depth_template.c"
 
-int ff_hadamard8_diff8x8_msa(MpegEncContext *s, uint8_t *dst, uint8_t *src,
+int ff_hadamard8_diff8x8_msa(MpegEncContext *s, const uint8_t *dst, const uint8_t *src,
                              ptrdiff_t stride, int h);
-int ff_hadamard8_intra8x8_msa(MpegEncContext *s, uint8_t *dst, uint8_t *src,
+int ff_hadamard8_intra8x8_msa(MpegEncContext *s, const uint8_t *dst, const uint8_t *src,
                               ptrdiff_t stride, int h);
-int ff_hadamard8_diff16_msa(MpegEncContext *s, uint8_t *dst, uint8_t *src,
+int ff_hadamard8_diff16_msa(MpegEncContext *s, const uint8_t *dst, const uint8_t *src,
                             ptrdiff_t stride, int h);
-int ff_hadamard8_intra16_msa(MpegEncContext *s, uint8_t *dst, uint8_t *src,
+int ff_hadamard8_intra16_msa(MpegEncContext *s, const uint8_t *dst, const uint8_t *src,
                              ptrdiff_t stride, int h);
-int ff_pix_abs16_msa(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs16_msa(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                      ptrdiff_t stride, int h);
-int ff_pix_abs16_x2_msa(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs16_x2_msa(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                         ptrdiff_t stride, int h);
-int ff_pix_abs16_y2_msa(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs16_y2_msa(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                         ptrdiff_t stride, int h);
-int ff_pix_abs16_xy2_msa(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs16_xy2_msa(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                          ptrdiff_t stride, int h);
-int ff_pix_abs8_msa(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs8_msa(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                     ptrdiff_t stride, int h);
-int ff_pix_abs8_x2_msa(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs8_x2_msa(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                        ptrdiff_t stride, int h);
-int ff_pix_abs8_y2_msa(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs8_y2_msa(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                        ptrdiff_t stride, int h);
-int ff_pix_abs8_xy2_msa(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs8_xy2_msa(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                         ptrdiff_t stride, int h);
-int ff_sse16_msa(MpegEncContext *v, uint8_t *pu8Src, uint8_t *pu8Ref,
+int ff_sse16_msa(MpegEncContext *v, const uint8_t *pu8Src, const uint8_t *pu8Ref,
                  ptrdiff_t stride, int i32Height);
-int ff_sse8_msa(MpegEncContext *v, uint8_t *pu8Src, uint8_t *pu8Ref,
+int ff_sse8_msa(MpegEncContext *v, const uint8_t *pu8Src, const uint8_t *pu8Ref,
                 ptrdiff_t stride, int i32Height);
-int ff_sse4_msa(MpegEncContext *v, uint8_t *pu8Src, uint8_t *pu8Ref,
+int ff_sse4_msa(MpegEncContext *v, const uint8_t *pu8Src, const uint8_t *pu8Ref,
                 ptrdiff_t stride, int i32Height);
-void ff_add_pixels8_msa(uint8_t *av_restrict pixels, int16_t *block,
+void ff_add_pixels8_msa(const uint8_t *av_restrict pixels, int16_t *block,
                         ptrdiff_t stride);
 
 #endif  // #ifndef AVCODEC_MIPS_ME_CMP_MIPS_H
diff --git a/libavcodec/mips/me_cmp_msa.c b/libavcodec/mips/me_cmp_msa.c
index 7cb7af0047..00a3cfd53f 100644
--- a/libavcodec/mips/me_cmp_msa.c
+++ b/libavcodec/mips/me_cmp_msa.c
@@ -21,8 +21,8 @@
 #include "libavutil/mips/generic_macros_msa.h"
 #include "me_cmp_mips.h"
 
-static uint32_t sad_8width_msa(uint8_t *src, int32_t src_stride,
-                               uint8_t *ref, int32_t ref_stride,
+static uint32_t sad_8width_msa(const uint8_t *src, int32_t src_stride,
+                               const uint8_t *ref, int32_t ref_stride,
                                int32_t height)
 {
     int32_t ht_cnt;
@@ -43,8 +43,8 @@ static uint32_t sad_8width_msa(uint8_t *src, int32_t src_stride,
     return (HADD_UH_U32(sad));
 }
 
-static uint32_t sad_16width_msa(uint8_t *src, int32_t src_stride,
-                                uint8_t *ref, int32_t ref_stride,
+static uint32_t sad_16width_msa(const uint8_t *src, int32_t src_stride,
+                                const uint8_t *ref, int32_t ref_stride,
                                 int32_t height)
 {
     int32_t ht_cnt;
@@ -68,9 +68,9 @@ static uint32_t sad_16width_msa(uint8_t *src, int32_t src_stride,
     return (HADD_UH_U32(sad));
 }
 
-static uint32_t sad_horiz_bilinear_filter_8width_msa(uint8_t *src,
+static uint32_t sad_horiz_bilinear_filter_8width_msa(const uint8_t *src,
                                                      int32_t src_stride,
-                                                     uint8_t *ref,
+                                                     const uint8_t *ref,
                                                      int32_t ref_stride,
                                                      int32_t height)
 {
@@ -110,9 +110,9 @@ static uint32_t sad_horiz_bilinear_filter_8width_msa(uint8_t *src,
     return (HADD_UH_U32(sad));
 }
 
-static uint32_t sad_horiz_bilinear_filter_16width_msa(uint8_t *src,
+static uint32_t sad_horiz_bilinear_filter_16width_msa(const uint8_t *src,
                                                       int32_t src_stride,
-                                                      uint8_t *ref,
+                                                      const uint8_t *ref,
                                                       int32_t ref_stride,
                                                       int32_t height)
 {
@@ -148,9 +148,9 @@ static uint32_t sad_horiz_bilinear_filter_16width_msa(uint8_t *src,
     return (HADD_UH_U32(sad));
 }
 
-static uint32_t sad_vert_bilinear_filter_8width_msa(uint8_t *src,
+static uint32_t sad_vert_bilinear_filter_8width_msa(const uint8_t *src,
                                                     int32_t src_stride,
-                                                    uint8_t *ref,
+                                                    const uint8_t *ref,
                                                     int32_t ref_stride,
                                                     int32_t height)
 {
@@ -186,9 +186,9 @@ static uint32_t sad_vert_bilinear_filter_8width_msa(uint8_t *src,
     return (HADD_UH_U32(sad));
 }
 
-static uint32_t sad_vert_bilinear_filter_16width_msa(uint8_t *src,
+static uint32_t sad_vert_bilinear_filter_16width_msa(const uint8_t *src,
                                                      int32_t src_stride,
-                                                     uint8_t *ref,
+                                                     const uint8_t *ref,
                                                      int32_t ref_stride,
                                                      int32_t height)
 {
@@ -224,9 +224,9 @@ static uint32_t sad_vert_bilinear_filter_16width_msa(uint8_t *src,
     return (HADD_UH_U32(sad));
 }
 
-static uint32_t sad_hv_bilinear_filter_8width_msa(uint8_t *src,
+static uint32_t sad_hv_bilinear_filter_8width_msa(const uint8_t *src,
                                                   int32_t src_stride,
-                                                  uint8_t *ref,
+                                                  const uint8_t *ref,
                                                   int32_t ref_stride,
                                                   int32_t height)
 {
@@ -280,9 +280,9 @@ static uint32_t sad_hv_bilinear_filter_8width_msa(uint8_t *src,
     return (HADD_UH_U32(sad));
 }
 
-static uint32_t sad_hv_bilinear_filter_16width_msa(uint8_t *src,
+static uint32_t sad_hv_bilinear_filter_16width_msa(const uint8_t *src,
                                                    int32_t src_stride,
-                                                   uint8_t *ref,
+                                                   const uint8_t *ref,
                                                    int32_t ref_stride,
                                                    int32_t height)
 {
@@ -403,8 +403,8 @@ static uint32_t sad_hv_bilinear_filter_16width_msa(uint8_t *src,
     DPADD_SH2_SW(res_l0_m, res_l1_m, res_l0_m, res_l1_m, var, var);  \
 }
 
-static uint32_t sse_4width_msa(uint8_t *src_ptr, int32_t src_stride,
-                               uint8_t *ref_ptr, int32_t ref_stride,
+static uint32_t sse_4width_msa(const uint8_t *src_ptr, int32_t src_stride,
+                               const uint8_t *ref_ptr, int32_t ref_stride,
                                int32_t height)
 {
     int32_t ht_cnt;
@@ -431,8 +431,8 @@ static uint32_t sse_4width_msa(uint8_t *src_ptr, int32_t src_stride,
     return sse;
 }
 
-static uint32_t sse_8width_msa(uint8_t *src_ptr, int32_t src_stride,
-                               uint8_t *ref_ptr, int32_t ref_stride,
+static uint32_t sse_8width_msa(const uint8_t *src_ptr, int32_t src_stride,
+                               const uint8_t *ref_ptr, int32_t ref_stride,
                                int32_t height)
 {
     int32_t ht_cnt;
@@ -458,8 +458,8 @@ static uint32_t sse_8width_msa(uint8_t *src_ptr, int32_t src_stride,
     return sse;
 }
 
-static uint32_t sse_16width_msa(uint8_t *src_ptr, int32_t src_stride,
-                                uint8_t *ref_ptr, int32_t ref_stride,
+static uint32_t sse_16width_msa(const uint8_t *src_ptr, int32_t src_stride,
+                                const uint8_t *ref_ptr, int32_t ref_stride,
                                 int32_t height)
 {
     int32_t ht_cnt;
@@ -498,8 +498,8 @@ static uint32_t sse_16width_msa(uint8_t *src_ptr, int32_t src_stride,
     return sse;
 }
 
-static int32_t hadamard_diff_8x8_msa(uint8_t *src, int32_t src_stride,
-                                     uint8_t *ref, int32_t ref_stride)
+static int32_t hadamard_diff_8x8_msa(const uint8_t *src, int32_t src_stride,
+                                     const uint8_t *ref, int32_t ref_stride)
 {
     v16u8 src0, src1, src2, src3, src4, src5, src6, src7;
     v16u8 ref0, ref1, ref2, ref3, ref4, ref5, ref6, ref7;
@@ -543,8 +543,8 @@ static int32_t hadamard_diff_8x8_msa(uint8_t *src, int32_t src_stride,
     return (HADD_UH_U32(sum));
 }
 
-static int32_t hadamard_intra_8x8_msa(uint8_t *src, int32_t src_stride,
-                                      uint8_t *ref, int32_t ref_stride)
+static int32_t hadamard_intra_8x8_msa(const uint8_t *src, int32_t src_stride,
+                                      const uint8_t *ref, int32_t ref_stride)
 {
     int32_t sum_res = 0;
     v16u8 src0, src1, src2, src3, src4, src5, src6, src7;
@@ -587,79 +587,79 @@ static int32_t hadamard_intra_8x8_msa(uint8_t *src, int32_t src_stride,
     return sum_res;
 }
 
-int ff_pix_abs16_msa(MpegEncContext *v, uint8_t *src, uint8_t *ref,
+int ff_pix_abs16_msa(MpegEncContext *v, const uint8_t *src, const uint8_t *ref,
                      ptrdiff_t stride, int height)
 {
     return sad_16width_msa(src, stride, ref, stride, height);
 }
 
-int ff_pix_abs8_msa(MpegEncContext *v, uint8_t *src, uint8_t *ref,
+int ff_pix_abs8_msa(MpegEncContext *v, const uint8_t *src, const uint8_t *ref,
                     ptrdiff_t stride, int height)
 {
     return sad_8width_msa(src, stride, ref, stride, height);
 }
 
-int ff_pix_abs16_x2_msa(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs16_x2_msa(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                         ptrdiff_t stride, int h)
 {
     return sad_horiz_bilinear_filter_16width_msa(pix1, stride, pix2, stride, h);
 }
 
-int ff_pix_abs16_y2_msa(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs16_y2_msa(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                         ptrdiff_t stride, int h)
 {
     return sad_vert_bilinear_filter_16width_msa(pix1, stride, pix2, stride, h);
 }
 
-int ff_pix_abs16_xy2_msa(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs16_xy2_msa(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                          ptrdiff_t stride, int h)
 {
     return sad_hv_bilinear_filter_16width_msa(pix1, stride, pix2, stride, h);
 }
 
-int ff_pix_abs8_x2_msa(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs8_x2_msa(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                        ptrdiff_t stride, int h)
 {
     return sad_horiz_bilinear_filter_8width_msa(pix1, stride, pix2, stride, h);
 }
 
-int ff_pix_abs8_y2_msa(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs8_y2_msa(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                        ptrdiff_t stride, int h)
 {
     return sad_vert_bilinear_filter_8width_msa(pix1, stride, pix2, stride, h);
 }
 
-int ff_pix_abs8_xy2_msa(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_pix_abs8_xy2_msa(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                         ptrdiff_t stride, int h)
 {
     return sad_hv_bilinear_filter_8width_msa(pix1, stride, pix2, stride, h);
 }
 
-int ff_sse16_msa(MpegEncContext *v, uint8_t *src, uint8_t *ref,
+int ff_sse16_msa(MpegEncContext *v, const uint8_t *src, const uint8_t *ref,
                  ptrdiff_t stride, int height)
 {
     return sse_16width_msa(src, stride, ref, stride, height);
 }
 
-int ff_sse8_msa(MpegEncContext *v, uint8_t *src, uint8_t *ref,
+int ff_sse8_msa(MpegEncContext *v, const uint8_t *src, const uint8_t *ref,
                 ptrdiff_t stride, int height)
 {
     return sse_8width_msa(src, stride, ref, stride, height);
 }
 
-int ff_sse4_msa(MpegEncContext *v, uint8_t *src, uint8_t *ref,
+int ff_sse4_msa(MpegEncContext *v, const uint8_t *src, const uint8_t *ref,
                 ptrdiff_t stride, int height)
 {
     return sse_4width_msa(src, stride, ref, stride, height);
 }
 
-int ff_hadamard8_diff8x8_msa(MpegEncContext *s, uint8_t *dst, uint8_t *src,
+int ff_hadamard8_diff8x8_msa(MpegEncContext *s, const uint8_t *dst, const uint8_t *src,
                              ptrdiff_t stride, int h)
 {
     return hadamard_diff_8x8_msa(src, stride, dst, stride);
 }
 
-int ff_hadamard8_intra8x8_msa(MpegEncContext *s, uint8_t *dst, uint8_t *src,
+int ff_hadamard8_intra8x8_msa(MpegEncContext *s, const uint8_t *dst, const uint8_t *src,
                               ptrdiff_t stride, int h)
 {
     return hadamard_intra_8x8_msa(src, stride, dst, stride);
@@ -667,7 +667,7 @@ int ff_hadamard8_intra8x8_msa(MpegEncContext *s, uint8_t *dst, uint8_t *src,
 
 /* Hadamard Transform functions */
 #define WRAPPER8_16_SQ(name8, name16)                      \
-int name16(MpegEncContext *s, uint8_t *dst, uint8_t *src,  \
+int name16(MpegEncContext *s, const uint8_t *dst, const uint8_t *src,  \
            ptrdiff_t stride, int h)                        \
 {                                                          \
     int score = 0;                                         \
diff --git a/libavcodec/motion_est.c b/libavcodec/motion_est.c
index 62c5b28364..0903536697 100644
--- a/libavcodec/motion_est.c
+++ b/libavcodec/motion_est.c
@@ -293,7 +293,7 @@ static int cmp_qpel(MpegEncContext *s, const int x, const int y, const int subx,
 
 #include "motion_est_template.c"
 
-static int zero_cmp(MpegEncContext *s, uint8_t *a, uint8_t *b,
+static int zero_cmp(MpegEncContext *s, const uint8_t *a, const uint8_t *b,
                     ptrdiff_t stride, int h)
 {
     return 0;
diff --git a/libavcodec/ppc/me_cmp.c b/libavcodec/ppc/me_cmp.c
index 17f9a4f016..90f21525d7 100644
--- a/libavcodec/ppc/me_cmp.c
+++ b/libavcodec/ppc/me_cmp.c
@@ -51,7 +51,7 @@
     iv = vec_vsx_ld(1,  pix);\
 }
 #endif
-static int sad16_x2_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int sad16_x2_altivec(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                             ptrdiff_t stride, int h)
 {
     int i;
@@ -91,7 +91,7 @@ static int sad16_x2_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static int sad16_y2_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int sad16_y2_altivec(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                             ptrdiff_t stride, int h)
 {
     int i;
@@ -102,7 +102,7 @@ static int sad16_y2_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     vector unsigned int sad = (vector unsigned int) vec_splat_u32(0);
     vector signed int sumdiffs;
 
-    uint8_t *pix3 = pix2 + stride;
+    const uint8_t *pix3 = pix2 + stride;
 
     /* Due to the fact that pix3 = pix2 + stride, the pix3 of one
      * iteration becomes pix2 in the next iteration. We can use this
@@ -141,12 +141,12 @@ static int sad16_y2_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static int sad16_xy2_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int sad16_xy2_altivec(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                              ptrdiff_t stride, int h)
 {
     int i;
     int  __attribute__((aligned(16))) s = 0;
-    uint8_t *pix3 = pix2 + stride;
+    const uint8_t *pix3 = pix2 + stride;
     const vector unsigned char zero =
         (const vector unsigned char) vec_splat_u8(0);
     const vector unsigned short two =
@@ -230,7 +230,7 @@ static int sad16_xy2_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static int sad16_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int sad16_altivec(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                          ptrdiff_t stride, int h)
 {
     int i;
@@ -265,7 +265,7 @@ static int sad16_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static int sad8_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int sad8_altivec(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                         ptrdiff_t stride, int h)
 {
     int i;
@@ -309,7 +309,7 @@ static int sad8_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
 
 /* Sum of Squared Errors for an 8x8 block, AltiVec-enhanced.
  * It's the sad8_altivec code above w/ squaring added. */
-static int sse8_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int sse8_altivec(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                         ptrdiff_t stride, int h)
 {
     int i;
@@ -354,7 +354,7 @@ static int sse8_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
 
 /* Sum of Squared Errors for a 16x16 block, AltiVec-enhanced.
  * It's the sad16_altivec code above w/ squaring added. */
-static int sse16_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+static int sse16_altivec(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                          ptrdiff_t stride, int h)
 {
     int i;
@@ -392,8 +392,8 @@ static int sse16_altivec(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
     return s;
 }
 
-static int hadamard8_diff8x8_altivec(MpegEncContext *s, uint8_t *dst,
-                                     uint8_t *src, ptrdiff_t stride, int h)
+static int hadamard8_diff8x8_altivec(MpegEncContext *s, const uint8_t *dst,
+                                     const uint8_t *src, ptrdiff_t stride, int h)
 {
     int __attribute__((aligned(16))) sum;
     register const vector unsigned char vzero =
@@ -518,8 +518,8 @@ static int hadamard8_diff8x8_altivec(MpegEncContext *s, uint8_t *dst,
  * On the 970, the hand-made RA is still a win (around 690 vs. around 780),
  * but xlc goes to around 660 on the regular C code...
  */
-static int hadamard8_diff16x8_altivec(MpegEncContext *s, uint8_t *dst,
-                                      uint8_t *src, ptrdiff_t stride, int h)
+static int hadamard8_diff16x8_altivec(MpegEncContext *s, const uint8_t *dst,
+                                      const uint8_t *src, ptrdiff_t stride, int h)
 {
     int __attribute__((aligned(16))) sum;
     register vector signed short
@@ -709,8 +709,8 @@ static int hadamard8_diff16x8_altivec(MpegEncContext *s, uint8_t *dst,
     return sum;
 }
 
-static int hadamard8_diff16_altivec(MpegEncContext *s, uint8_t *dst,
-                                    uint8_t *src, ptrdiff_t stride, int h)
+static int hadamard8_diff16_altivec(MpegEncContext *s, const uint8_t *dst,
+                                    const uint8_t *src, ptrdiff_t stride, int h)
 {
     int score = hadamard8_diff16x8_altivec(s, dst, src, stride, 8);
 
diff --git a/libavcodec/snow_dwt.c b/libavcodec/snow_dwt.c
index e196fefd24..18b315ef66 100644
--- a/libavcodec/snow_dwt.c
+++ b/libavcodec/snow_dwt.c
@@ -740,7 +740,7 @@ void ff_spatial_idwt(IDWTELEM *buffer, IDWTELEM *temp, int width, int height,
                               decomposition_count, y);
 }
 
-static inline int w_c(struct MpegEncContext *v, uint8_t *pix1, uint8_t *pix2, ptrdiff_t line_size,
+static inline int w_c(struct MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2, ptrdiff_t line_size,
                       int w, int h, int type)
 {
     int s, i, j;
@@ -809,32 +809,32 @@ static inline int w_c(struct MpegEncContext *v, uint8_t *pix1, uint8_t *pix2, pt
     return s >> 9;
 }
 
-static int w53_8_c(struct MpegEncContext *v, uint8_t *pix1, uint8_t *pix2, ptrdiff_t line_size, int h)
+static int w53_8_c(struct MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2, ptrdiff_t line_size, int h)
 {
     return w_c(v, pix1, pix2, line_size, 8, h, 1);
 }
 
-static int w97_8_c(struct MpegEncContext *v, uint8_t *pix1, uint8_t *pix2, ptrdiff_t line_size, int h)
+static int w97_8_c(struct MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2, ptrdiff_t line_size, int h)
 {
     return w_c(v, pix1, pix2, line_size, 8, h, 0);
 }
 
-static int w53_16_c(struct MpegEncContext *v, uint8_t *pix1, uint8_t *pix2, ptrdiff_t line_size, int h)
+static int w53_16_c(struct MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2, ptrdiff_t line_size, int h)
 {
     return w_c(v, pix1, pix2, line_size, 16, h, 1);
 }
 
-static int w97_16_c(struct MpegEncContext *v, uint8_t *pix1, uint8_t *pix2, ptrdiff_t line_size, int h)
+static int w97_16_c(struct MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2, ptrdiff_t line_size, int h)
 {
     return w_c(v, pix1, pix2, line_size, 16, h, 0);
 }
 
-int ff_w53_32_c(struct MpegEncContext *v, uint8_t *pix1, uint8_t *pix2, ptrdiff_t line_size, int h)
+int ff_w53_32_c(struct MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2, ptrdiff_t line_size, int h)
 {
     return w_c(v, pix1, pix2, line_size, 32, h, 1);
 }
 
-int ff_w97_32_c(struct MpegEncContext *v, uint8_t *pix1, uint8_t *pix2, ptrdiff_t line_size, int h)
+int ff_w97_32_c(struct MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2, ptrdiff_t line_size, int h)
 {
     return w_c(v, pix1, pix2, line_size, 32, h, 0);
 }
diff --git a/libavcodec/snow_dwt.h b/libavcodec/snow_dwt.h
index 390bc57130..15b8a3007b 100644
--- a/libavcodec/snow_dwt.h
+++ b/libavcodec/snow_dwt.h
@@ -104,8 +104,8 @@ void ff_snow_inner_add_yblock(const uint8_t *obmc, const int obmc_stride,
                               int src_y, int src_stride, slice_buffer *sb,
                               int add, uint8_t *dst8);
 
-int ff_w53_32_c(struct MpegEncContext *v, uint8_t *pix1, uint8_t *pix2, ptrdiff_t line_size, int h);
-int ff_w97_32_c(struct MpegEncContext *v, uint8_t *pix1, uint8_t *pix2, ptrdiff_t line_size, int h);
+int ff_w53_32_c(struct MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2, ptrdiff_t line_size, int h);
+int ff_w97_32_c(struct MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2, ptrdiff_t line_size, int h);
 
 void ff_spatial_dwt(int *buffer, int *temp, int width, int height, int stride,
                     int type, int decomposition_count);
diff --git a/libavcodec/x86/me_cmp.asm b/libavcodec/x86/me_cmp.asm
index 10809bbfb1..eb036ee4bc 100644
--- a/libavcodec/x86/me_cmp.asm
+++ b/libavcodec/x86/me_cmp.asm
@@ -38,7 +38,7 @@ SECTION .text
     psubw           %1, %2
 %endmacro
 
-; %1=uint8_t *pix1, %2=uint8_t *pix2, %3=static offset, %4=stride, %5=stride*3
+; %1=const uint8_t *pix1, %2=const uint8_t *pix2, %3=static offset, %4=stride, %5=stride*3
 ; %6=temporary storage location
 ; this macro requires $mmsize stack space (aligned) on %6 (except on SSE+x86-64)
 %macro DIFF_PIXELS_8 6
@@ -214,8 +214,8 @@ hadamard8x8_diff %+ SUFFIX:
 hadamard8_16_wrapper %1, 3
 %elif cpuflag(mmx)
 ALIGN 16
-; int ff_hadamard8_diff_ ## cpu(MpegEncContext *s, uint8_t *src1,
-;                               uint8_t *src2, ptrdiff_t stride, int h)
+; int ff_hadamard8_diff_ ## cpu(MpegEncContext *s, const uint8_t *src1,
+;                               const uint8_t *src2, ptrdiff_t stride, int h)
 ; r0 = void *s = unused, int h = unused (always 8)
 ; note how r1, r2 and r3 are not clobbered in this function, so 16x16
 ; can simply call this 2x2x (and that's why we access rsp+gprsize
@@ -278,7 +278,7 @@ INIT_XMM ssse3
 %define ABS_SUM_8x8 ABS_SUM_8x8_64
 HADAMARD8_DIFF 9
 
-; int ff_sse*_*(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+; int ff_sse*_*(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
 ;               ptrdiff_t line_size, int h)
 
 %macro SUM_SQUARED_ERRORS 1
@@ -357,7 +357,7 @@ INIT_XMM sse2
 SUM_SQUARED_ERRORS 16
 
 ;-----------------------------------------------
-;int ff_sum_abs_dctelem(int16_t *block)
+;int ff_sum_abs_dctelem(const int16_t *block)
 ;-----------------------------------------------
 ; %1 = number of xmm registers used
 ; %2 = number of inline loops
@@ -390,7 +390,7 @@ INIT_XMM ssse3
 SUM_ABS_DCTELEM 6, 2
 
 ;------------------------------------------------------------------------------
-; int ff_hf_noise*_mmx(uint8_t *pix1, ptrdiff_t lsize, int h)
+; int ff_hf_noise*_mmx(const uint8_t *pix1, ptrdiff_t lsize, int h)
 ;------------------------------------------------------------------------------
 ; %1 = 8/16. %2-5=m#
 %macro HF_NOISE_PART1 5
@@ -466,7 +466,7 @@ HF_NOISE 8
 HF_NOISE 16
 
 ;---------------------------------------------------------------------------------------
-;int ff_sad_<opt>(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2, ptrdiff_t stride, int h);
+;int ff_sad_<opt>(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2, ptrdiff_t stride, int h);
 ;---------------------------------------------------------------------------------------
 ;%1 = 8/16
 %macro SAD 1
@@ -521,7 +521,7 @@ INIT_XMM sse2
 SAD 16
 
 ;------------------------------------------------------------------------------------------
-;int ff_sad_x2_<opt>(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2, ptrdiff_t stride, int h);
+;int ff_sad_x2_<opt>(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2, ptrdiff_t stride, int h);
 ;------------------------------------------------------------------------------------------
 ;%1 = 8/16
 %macro SAD_X2 1
@@ -598,7 +598,7 @@ INIT_XMM sse2
 SAD_X2 16
 
 ;------------------------------------------------------------------------------------------
-;int ff_sad_y2_<opt>(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2, ptrdiff_t stride, int h);
+;int ff_sad_y2_<opt>(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2, ptrdiff_t stride, int h);
 ;------------------------------------------------------------------------------------------
 ;%1 = 8/16
 %macro SAD_Y2 1
@@ -668,7 +668,7 @@ INIT_XMM sse2
 SAD_Y2 16
 
 ;-------------------------------------------------------------------------------------------
-;int ff_sad_approx_xy2_<opt>(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2, ptrdiff_t stride, int h);
+;int ff_sad_approx_xy2_<opt>(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2, ptrdiff_t stride, int h);
 ;-------------------------------------------------------------------------------------------
 ;%1 = 8/16
 %macro SAD_APPROX_XY2 1
@@ -769,7 +769,7 @@ INIT_XMM sse2
 SAD_APPROX_XY2 16
 
 ;--------------------------------------------------------------------
-;int ff_vsad_intra(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+;int ff_vsad_intra(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
 ;                  ptrdiff_t line_size, int h);
 ;--------------------------------------------------------------------
 ; %1 = 8/16
@@ -830,7 +830,7 @@ INIT_XMM sse2
 VSAD_INTRA 16
 
 ;---------------------------------------------------------------------
-;int ff_vsad_approx(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+;int ff_vsad_approx(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
 ;                   ptrdiff_t line_size, int h);
 ;---------------------------------------------------------------------
 ; %1 = 8/16
diff --git a/libavcodec/x86/me_cmp_init.c b/libavcodec/x86/me_cmp_init.c
index 61e9396b8f..f140381c98 100644
--- a/libavcodec/x86/me_cmp_init.c
+++ b/libavcodec/x86/me_cmp_init.c
@@ -30,65 +30,65 @@
 #include "libavcodec/me_cmp.h"
 #include "libavcodec/mpegvideo.h"
 
-int ff_sum_abs_dctelem_sse2(int16_t *block);
-int ff_sum_abs_dctelem_ssse3(int16_t *block);
-int ff_sse8_mmx(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_sum_abs_dctelem_sse2(const int16_t *block);
+int ff_sum_abs_dctelem_ssse3(const int16_t *block);
+int ff_sse8_mmx(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                 ptrdiff_t stride, int h);
-int ff_sse16_mmx(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_sse16_mmx(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                  ptrdiff_t stride, int h);
-int ff_sse16_sse2(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_sse16_sse2(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                   ptrdiff_t stride, int h);
-int ff_hf_noise8_mmx(uint8_t *pix1, ptrdiff_t stride, int h);
-int ff_hf_noise16_mmx(uint8_t *pix1, ptrdiff_t stride, int h);
-int ff_sad8_mmxext(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_hf_noise8_mmx(const uint8_t *pix1, ptrdiff_t stride, int h);
+int ff_hf_noise16_mmx(const uint8_t *pix1, ptrdiff_t stride, int h);
+int ff_sad8_mmxext(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                    ptrdiff_t stride, int h);
-int ff_sad16_mmxext(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_sad16_mmxext(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                     ptrdiff_t stride, int h);
-int ff_sad16_sse2(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_sad16_sse2(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                   ptrdiff_t stride, int h);
-int ff_sad8_x2_mmxext(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_sad8_x2_mmxext(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                       ptrdiff_t stride, int h);
-int ff_sad16_x2_mmxext(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_sad16_x2_mmxext(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                        ptrdiff_t stride, int h);
-int ff_sad16_x2_sse2(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_sad16_x2_sse2(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                      ptrdiff_t stride, int h);
-int ff_sad8_y2_mmxext(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_sad8_y2_mmxext(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                       ptrdiff_t stride, int h);
-int ff_sad16_y2_mmxext(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_sad16_y2_mmxext(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                        ptrdiff_t stride, int h);
-int ff_sad16_y2_sse2(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_sad16_y2_sse2(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                      ptrdiff_t stride, int h);
-int ff_sad8_approx_xy2_mmxext(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_sad8_approx_xy2_mmxext(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                               ptrdiff_t stride, int h);
-int ff_sad16_approx_xy2_mmxext(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_sad16_approx_xy2_mmxext(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                                ptrdiff_t stride, int h);
-int ff_sad16_approx_xy2_sse2(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_sad16_approx_xy2_sse2(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                              ptrdiff_t stride, int h);
-int ff_vsad_intra8_mmxext(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_vsad_intra8_mmxext(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                           ptrdiff_t stride, int h);
-int ff_vsad_intra16_mmxext(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_vsad_intra16_mmxext(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                            ptrdiff_t stride, int h);
-int ff_vsad_intra16_sse2(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_vsad_intra16_sse2(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                          ptrdiff_t stride, int h);
-int ff_vsad8_approx_mmxext(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_vsad8_approx_mmxext(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                     ptrdiff_t stride, int h);
-int ff_vsad16_approx_mmxext(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_vsad16_approx_mmxext(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                      ptrdiff_t stride, int h);
-int ff_vsad16_approx_sse2(MpegEncContext *v, uint8_t *pix1, uint8_t *pix2,
+int ff_vsad16_approx_sse2(MpegEncContext *v, const uint8_t *pix1, const uint8_t *pix2,
                    ptrdiff_t stride, int h);
 
 #define hadamard_func(cpu)                                                    \
-    int ff_hadamard8_diff_ ## cpu(MpegEncContext *s, uint8_t *src1,           \
-                                  uint8_t *src2, ptrdiff_t stride, int h);    \
-    int ff_hadamard8_diff16_ ## cpu(MpegEncContext *s, uint8_t *src1,         \
-                                    uint8_t *src2, ptrdiff_t stride, int h);
+    int ff_hadamard8_diff_ ## cpu(MpegEncContext *s, const uint8_t *src1,     \
+                                  const uint8_t *src2, ptrdiff_t stride, int h); \
+    int ff_hadamard8_diff16_ ## cpu(MpegEncContext *s, const uint8_t *src1,   \
+                                    const uint8_t *src2, ptrdiff_t stride, int h);
 
 hadamard_func(mmxext)
 hadamard_func(sse2)
 hadamard_func(ssse3)
 
 #if HAVE_X86ASM
-static int nsse16_mmx(MpegEncContext *c, uint8_t *pix1, uint8_t *pix2,
+static int nsse16_mmx(MpegEncContext *c, const uint8_t *pix1, const uint8_t *pix2,
                       ptrdiff_t stride, int h)
 {
     int score1, score2;
@@ -106,7 +106,7 @@ static int nsse16_mmx(MpegEncContext *c, uint8_t *pix1, uint8_t *pix2,
         return score1 + FFABS(score2) * 8;
 }
 
-static int nsse8_mmx(MpegEncContext *c, uint8_t *pix1, uint8_t *pix2,
+static int nsse8_mmx(MpegEncContext *c, const uint8_t *pix1, const uint8_t *pix2,
                      ptrdiff_t stride, int h)
 {
     int score1 = ff_sse8_mmx(c, pix1, pix2, stride, h);
@@ -129,7 +129,7 @@ DECLARE_ASM_CONST(8, uint64_t, round_tab)[3] = {
     0x0002000200020002ULL,
 };
 
-static inline void sad8_4_mmx(uint8_t *blk1, uint8_t *blk2,
+static inline void sad8_4_mmx(const uint8_t *blk1, const uint8_t *blk2,
                               ptrdiff_t stride, int h)
 {
     x86_reg len = -stride * h;
@@ -199,8 +199,8 @@ static inline int sum_mmx(void)
 }
 
 #define PIX_SADXY(suf)                                                  \
-static int sad8_xy2_ ## suf(MpegEncContext *v, uint8_t *blk2,           \
-                            uint8_t *blk1, ptrdiff_t stride, int h)     \
+static int sad8_xy2_ ## suf(MpegEncContext *v, const uint8_t *blk2,     \
+                            const uint8_t *blk1, ptrdiff_t stride, int h) \
 {                                                                       \
     av_assert2(h == 8);                                                     \
     __asm__ volatile (                                                  \
@@ -213,8 +213,8 @@ static int sad8_xy2_ ## suf(MpegEncContext *v, uint8_t *blk2,           \
     return sum_ ## suf();                                               \
 }                                                                       \
                                                                         \
-static int sad16_xy2_ ## suf(MpegEncContext *v, uint8_t *blk2,          \
-                             uint8_t *blk1, ptrdiff_t stride, int h)    \
+static int sad16_xy2_ ## suf(MpegEncContext *v, const uint8_t *blk2,    \
+                             const uint8_t *blk1, ptrdiff_t stride, int h) \
 {                                                                       \
     __asm__ volatile (                                                  \
         "pxor %%mm7, %%mm7     \n\t"                                    \