diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index fa6c0bb9cd51e264cd882d1bc765799351e1c59b..682b62680084f4c2be7351be0a943e35085dba65 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -55,8 +55,10 @@ OBJS-$(CONFIG_AAC_ENCODER)             += aacenc.o aaccoder.o    \
                                           mpeg4audio.o
 OBJS-$(CONFIG_AASC_DECODER)            += aasc.o msrledec.o
 OBJS-$(CONFIG_AC3_DECODER)             += ac3dec.o ac3dec_data.o ac3.o
-OBJS-$(CONFIG_AC3_ENCODER)             += ac3enc_float.o ac3tab.o ac3.o
-OBJS-$(CONFIG_AC3_FIXED_ENCODER)       += ac3enc_fixed.o ac3tab.o ac3.o
+OBJS-$(CONFIG_AC3_ENCODER)             += ac3enc_float.o ac3tab.o ac3.o \
+                                          ac3dsp.o
+OBJS-$(CONFIG_AC3_FIXED_ENCODER)       += ac3enc_fixed.o ac3tab.o ac3.o \
+                                          ac3dsp.o
 OBJS-$(CONFIG_ALAC_DECODER)            += alac.o
 OBJS-$(CONFIG_ALAC_ENCODER)            += alacenc.o
 OBJS-$(CONFIG_ALS_DECODER)             += alsdec.o bgmc.o mpeg4audio.o
diff --git a/libavcodec/ac3dsp.c b/libavcodec/ac3dsp.c
new file mode 100644
index 0000000000000000000000000000000000000000..f688e6a72bdd40efacb4da268b2fc6a224dbc5c6
--- /dev/null
+++ b/libavcodec/ac3dsp.c
@@ -0,0 +1,51 @@
+/*
+ * AC-3 DSP utils
+ * Copyright (c) 2011 Justin Ruggles
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "avcodec.h"
+#include "ac3dsp.h"
+
+static void ac3_exponent_min_c(uint8_t *exp, int num_reuse_blocks, int nb_coefs)
+{
+    int blk, i;
+
+    if (!num_reuse_blocks)
+        return;
+
+    for (i = 0; i < nb_coefs; i++) {
+        uint8_t min_exp = *exp;
+        uint8_t *exp1 = exp + 256;
+        for (blk = 0; blk < num_reuse_blocks; blk++) {
+            uint8_t next_exp = *exp1;
+            if (next_exp < min_exp)
+                min_exp = next_exp;
+            exp1 += 256;
+        }
+        *exp++ = min_exp;
+    }
+}
+
+av_cold void ff_ac3dsp_init(AC3DSPContext *c)
+{
+    c->ac3_exponent_min = ac3_exponent_min_c;
+
+    if (HAVE_MMX)
+        ff_ac3dsp_init_x86(c);
+}
diff --git a/libavcodec/ac3dsp.h b/libavcodec/ac3dsp.h
new file mode 100644
index 0000000000000000000000000000000000000000..7f13b11f3b37e7a2bda12c2547b00f0b8494e70c
--- /dev/null
+++ b/libavcodec/ac3dsp.h
@@ -0,0 +1,43 @@
+/*
+ * AC-3 DSP utils
+ * Copyright (c) 2011 Justin Ruggles
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVCODEC_AC3DSP_H
+#define AVCODEC_AC3DSP_H
+
+#include <stdint.h>
+
+typedef struct AC3DSPContext {
+    /**
+     * Set each encoded exponent in a block to the minimum of itself and the
+     * exponents in the same frequency bin of up to 5 following blocks.
+     * @param exp   pointer to the start of the current block of exponents.
+     *              constraints: align 16
+     * @param num_reuse_blocks  number of blocks that will reuse exponents from the current block.
+     *                          constraints: range 0 to 5
+     * @param nb_coefs  number of frequency coefficients.
+     */
+    void (*ac3_exponent_min)(uint8_t *exp, int num_reuse_blocks, int nb_coefs);
+} AC3DSPContext;
+
+void ff_ac3dsp_init    (AC3DSPContext *c);
+void ff_ac3dsp_init_x86(AC3DSPContext *c);
+
+#endif /* AVCODEC_AC3DSP_H */
diff --git a/libavcodec/ac3enc.c b/libavcodec/ac3enc.c
index e41a0aec65d898e1999879c4a3f1280e6647386f..851fdc9caf1f474f1d03b8797b39e1900a429d2a 100644
--- a/libavcodec/ac3enc.c
+++ b/libavcodec/ac3enc.c
@@ -33,6 +33,7 @@
 #include "avcodec.h"
 #include "put_bits.h"
 #include "dsputil.h"
+#include "ac3dsp.h"
 #include "ac3.h"
 #include "audioconvert.h"
 
@@ -86,6 +87,7 @@ typedef struct AC3Block {
 typedef struct AC3EncodeContext {
     PutBitContext pb;                       ///< bitstream writer context
     DSPContext dsp;
+    AC3DSPContext ac3dsp;                   ///< AC-3 optimized functions
     AC3MDCTContext mdct;                    ///< MDCT context
 
     AC3Block blocks[AC3_MAX_BLOCKS];        ///< per-block info
@@ -458,7 +460,6 @@ static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy,
             exp_strategy[blk] = EXP_REUSE;
         exp += AC3_MAX_COEFS;
     }
-    emms_c();
 
     /* now select the encoding strategy type : if exponents are often
        recoded, we use a coarse encoding */
@@ -498,31 +499,6 @@ static void compute_exp_strategy(AC3EncodeContext *s)
 }
 
 
-/**
- * Set each encoded exponent in a block to the minimum of itself and the
- * exponents in the same frequency bin of up to 5 following blocks.
- */
-static void exponent_min(uint8_t *exp, int num_reuse_blocks, int nb_coefs)
-{
-    int blk, i;
-
-    if (!num_reuse_blocks)
-        return;
-
-    for (i = 0; i < nb_coefs; i++) {
-        uint8_t min_exp = *exp;
-        uint8_t *exp1 = exp + AC3_MAX_COEFS;
-        for (blk = 0; blk < num_reuse_blocks; blk++) {
-            uint8_t next_exp = *exp1;
-            if (next_exp < min_exp)
-                min_exp = next_exp;
-            exp1 += AC3_MAX_COEFS;
-        }
-        *exp++ = min_exp;
-    }
-}
-
-
 /**
  * Update the exponents so that they are the ones the decoder will decode.
  */
@@ -616,7 +592,7 @@ static void encode_exponents(AC3EncodeContext *s)
             num_reuse_blocks = blk1 - blk - 1;
 
             /* for the EXP_REUSE case we select the min of the exponents */
-            exponent_min(exp, num_reuse_blocks, nb_coefs);
+            s->ac3dsp.ac3_exponent_min(exp, num_reuse_blocks, nb_coefs);
 
             encode_exponents_blk_ch(exp, nb_coefs, exp_strategy[blk]);
 
@@ -704,6 +680,8 @@ static void process_exponents(AC3EncodeContext *s)
     encode_exponents(s);
 
     group_exponents(s);
+
+    emms_c();
 }
 
 
@@ -1856,6 +1834,7 @@ static av_cold int ac3_encode_init(AVCodecContext *avctx)
     avctx->coded_frame= avcodec_alloc_frame();
 
     dsputil_init(&s->dsp, avctx);
+    ff_ac3dsp_init(&s->ac3dsp);
 
     return 0;
 init_fail:
diff --git a/libavcodec/x86/Makefile b/libavcodec/x86/Makefile
index 83cec00442ef94a1777d350a96cd760bd9383d05..1b58fa121f9cdf8532d2f01076d7b0b9533100f2 100644
--- a/libavcodec/x86/Makefile
+++ b/libavcodec/x86/Makefile
@@ -17,6 +17,10 @@ MMX-OBJS-$(CONFIG_H264PRED)            += x86/h264_intrapred_init.o
 
 YASM-OBJS-$(CONFIG_VC1_DECODER)        += x86/vc1dsp_yasm.o
 
+MMX-OBJS-$(CONFIG_AC3_ENCODER)         += x86/ac3dsp_mmx.o
+MMX-OBJS-$(CONFIG_AC3_FIXED_ENCODER)   += x86/ac3dsp_mmx.o
+YASM-OBJS-$(CONFIG_AC3_ENCODER)        += x86/ac3dsp.o
+YASM-OBJS-$(CONFIG_AC3_FIXED_ENCODER)  += x86/ac3dsp.o
 MMX-OBJS-$(CONFIG_CAVS_DECODER)        += x86/cavsdsp_mmx.o
 MMX-OBJS-$(CONFIG_MP1FLOAT_DECODER)    += x86/mpegaudiodec_mmx.o
 MMX-OBJS-$(CONFIG_MP2FLOAT_DECODER)    += x86/mpegaudiodec_mmx.o
diff --git a/libavcodec/x86/ac3dsp.asm b/libavcodec/x86/ac3dsp.asm
new file mode 100644
index 0000000000000000000000000000000000000000..e71c51cf338e903ab3af0f5ad7898b449813c3de
--- /dev/null
+++ b/libavcodec/x86/ac3dsp.asm
@@ -0,0 +1,67 @@
+;*****************************************************************************
+;* x86-optimized AC-3 DSP utils
+;* Copyright (c) 2011 Justin Ruggles
+;*
+;* This file is part of FFmpeg.
+;*
+;* FFmpeg is free software; you can redistribute it and/or
+;* modify it under the terms of the GNU Lesser General Public
+;* License as published by the Free Software Foundation; either
+;* version 2.1 of the License, or (at your option) any later version.
+;*
+;* FFmpeg is distributed in the hope that it will be useful,
+;* but WITHOUT ANY WARRANTY; without even the implied warranty of
+;* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;* Lesser General Public License for more details.
+;*
+;* You should have received a copy of the GNU Lesser General Public
+;* License along with FFmpeg; if not, write to the Free Software
+;* 51, Inc., Foundation Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+;******************************************************************************
+
+%include "x86inc.asm"
+%include "x86util.asm"
+
+SECTION .text
+
+;-----------------------------------------------------------------------------
+; void ff_ac3_exponent_min(uint8_t *exp, int num_reuse_blocks, int nb_coefs)
+;-----------------------------------------------------------------------------
+
+%macro AC3_EXPONENT_MIN 1
+cglobal ac3_exponent_min_%1, 3,4,2, exp, reuse_blks, expn, offset
+    shl  reuse_blksq, 8
+    jz .end
+    LOOP_ALIGN
+.nextexp:
+    mov      offsetq, reuse_blksq
+    mova          m0, [expq+offsetq]
+    sub      offsetq, 256
+    LOOP_ALIGN
+.nextblk:
+    PMINUB        m0, [expq+offsetq], m1
+    sub      offsetq, 256
+    jae .nextblk
+    mova      [expq], m0
+    add         expq, mmsize
+    sub        expnq, mmsize
+    jg .nextexp
+.end:
+    REP_RET
+%endmacro
+
+%define PMINUB PMINUB_MMX
+%define LOOP_ALIGN
+INIT_MMX
+AC3_EXPONENT_MIN mmx
+%ifdef HAVE_MMX2
+%define PMINUB PMINUB_MMXEXT
+%define LOOP_ALIGN ALIGN 16
+AC3_EXPONENT_MIN mmxext
+%endif
+%ifdef HAVE_SSE
+INIT_XMM
+AC3_EXPONENT_MIN sse2
+%endif
+%undef PMINUB
+%undef LOOP_ALIGN
diff --git a/libavcodec/x86/ac3dsp_mmx.c b/libavcodec/x86/ac3dsp_mmx.c
new file mode 100644
index 0000000000000000000000000000000000000000..7ce3aa358dd100d8266f2c0d2707d094a649e0d6
--- /dev/null
+++ b/libavcodec/x86/ac3dsp_mmx.c
@@ -0,0 +1,45 @@
+/*
+ * x86-optimized AC-3 DSP utils
+ * Copyright (c) 2011 Justin Ruggles
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/x86_cpu.h"
+#include "dsputil_mmx.h"
+#include "libavcodec/ac3dsp.h"
+
+extern void ff_ac3_exponent_min_mmx   (uint8_t *exp, int num_reuse_blocks, int nb_coefs);
+extern void ff_ac3_exponent_min_mmxext(uint8_t *exp, int num_reuse_blocks, int nb_coefs);
+extern void ff_ac3_exponent_min_sse2  (uint8_t *exp, int num_reuse_blocks, int nb_coefs);
+
+av_cold void ff_ac3dsp_init_x86(AC3DSPContext *c)
+{
+    int mm_flags = av_get_cpu_flags();
+
+#if HAVE_YASM
+    if (mm_flags & AV_CPU_FLAG_MMX) {
+        c->ac3_exponent_min = ff_ac3_exponent_min_mmx;
+    }
+    if (mm_flags & AV_CPU_FLAG_MMX2 && HAVE_MMX2) {
+        c->ac3_exponent_min = ff_ac3_exponent_min_mmxext;
+    }
+    if (mm_flags & AV_CPU_FLAG_SSE2 && HAVE_SSE) {
+        c->ac3_exponent_min = ff_ac3_exponent_min_sse2;
+    }
+#endif
+}
diff --git a/libavcodec/x86/x86util.asm b/libavcodec/x86/x86util.asm
index 7cabc70b3193a3b64746c418c79fcf2e24b472b5..b28a6198f70ff67f83f3a19181a5dd32093646f3 100644
--- a/libavcodec/x86/x86util.asm
+++ b/libavcodec/x86/x86util.asm
@@ -434,3 +434,13 @@
     movh     [%7], %3
     movh  [%7+%8], %4
 %endmacro
+
+%macro PMINUB_MMX 3 ; dst, src, tmp
+    mova     %3, %1
+    psubusb  %3, %2
+    psubb    %1, %3
+%endmacro
+
+%macro PMINUB_MMXEXT 3 ; dst, src, ignored
+    pminub   %1, %2
+%endmacro