diff --git a/configure b/configure
index a479dee9fe3ace256176648c345c7af78d86e1b5..ae2aef4fe22fa80942db92d718f57007c743e60f 100755
--- a/configure
+++ b/configure
@@ -53,6 +53,7 @@ echo "  --cpu=CPU                force cpu to CPU  [$cpu]"
 echo "  --tune=PROCESSOR         tune code for a particular CPU (may fails or misperforms on other CPUs)"
 echo "  --powerpc-perf-enable    enable performance report on PPC (requires enabling PMC)"
 echo "  --disable-mmx            disable mmx usage"
+echo "  --disable-iwmmxt         disable iwmmxt usage"
 echo "  --disable-altivec        disable AltiVec usage"
 echo "  --disable-audio-oss      disable OSS audio support [default=no]"
 echo "  --disable-audio-beos     disable BeOS audio support [default=no]"
@@ -112,6 +113,7 @@ cpu=`uname -m`
 tune="generic"
 powerpc_perf="no"
 mmx="default"
+iwmmxt="default"
 altivec="default"
 mmi="default"
 case "$cpu" in
@@ -403,9 +405,9 @@ CODEC_LIST=`grep 'register_avcodec(&[a-z]' $source_path/libavcodec/allcodecs.c
 
 for opt do
   case "$opt" in
-  --prefix=*) prefix=`echo $opt | cut -d '=' -f 2`
+  --prefix=*) prefix=`echo $opt | cut -d '=' -f 2`; force_prefix=yes
   ;;
-  --libdir=*) libdir=`echo $opt | cut -d '=' -f 2`
+  --libdir=*) libdir=`echo $opt | cut -d '=' -f 2`; force_libdir=yes
   ;;
   --mandir=*) mandir=`echo $opt | cut -d '=' -f 2`
   ;;
@@ -413,7 +415,7 @@ for opt do
   ;;
   --cross-prefix=*) cross_prefix=`echo $opt | cut -d '=' -f 2`
   ;;
-  --cc=*) cc=`echo $opt | cut -d '=' -f 2`
+  --cc=*) cc=`echo $opt | cut -d '=' -f 2-`
   ;;
   --make=*) make=`echo $opt | cut -d '=' -f 2`
   ;;
@@ -433,6 +435,8 @@ for opt do
   ;;
   --disable-mmx) mmx="no"
   ;;
+  --disable-iwmmxt) iwmmxt="no"
+  ;;
   --disable-altivec) altivec="no"
   ;;
   --enable-gprof) gprof="yes"
@@ -614,6 +618,20 @@ if test $mmx = "default"; then
     fi
 fi
 
+# check iwmmxt support
+if test $iwmmxt = "default" -a $cpu = "armv4l"; then
+    cat > $TMPC << EOF
+        int main(void) { 
+        __asm__ __volatile__ ("wunpckelub wr6, wr4");
+        }
+EOF
+
+    iwmmxt=no
+    if ${cross_prefix}${cc} -o $TMPO $TMPC 2> /dev/null ; then
+        iwmmxt=yes
+    fi
+fi
+
 #Darwin CC versions
 needmdynamicnopic="no"
 if test $targetos = Darwin; then
@@ -792,8 +810,8 @@ if test "$mingw32" = "yes" ; then
     SLIBPREF=""
     SLIBSUF=".dll"
     EXESUF=".exe"
-    prefix="/c/Program Files/FFmpeg"
-    bindir="$prefix"
+    if test "$force_prefix" != yes; then prefix="/c/Program Files/FFmpeg"; fi
+    if test "$force_libdir" != yes; then bindir="$prefix"; fi
 fi
 
 cc="${cross_prefix}${cc}"
@@ -1144,6 +1162,9 @@ if test $cpu = "x86" -o $cpu = "x86_64"; then
 echo "MMX enabled      $mmx"
 echo "Vector Builtins  $builtin_vector"
 fi
+if test $cpu = "armv4l"; then
+echo "IWMMXT enabled   $iwmmxt"
+fi
 if test $cpu = "mips"; then
 echo "MMI enabled      $mmi"
 fi
@@ -1299,6 +1320,10 @@ if test "$builtin_vector" = "yes" ; then
   echo "TARGET_BUILTIN_VECTOR=yes" >> config.mak
   echo "#define HAVE_BUILTIN_VECTOR 1" >> $TMPH
 fi
+if test "$iwmmxt" = "yes" ; then
+  echo "TARGET_IWMMXT=yes" >> config.mak
+  echo "#define HAVE_IWMMXT 1" >> $TMPH
+fi
 if test "$mmi" = "yes" ; then
   echo "TARGET_MMI=yes" >> config.mak
   echo "#define HAVE_MMI 1" >> $TMPH
diff --git a/libavcodec/armv4l/dsputil_arm.c b/libavcodec/armv4l/dsputil_arm.c
index 4ba6280963784a6af93a33db9d5c5f43a66f9186..0195c3ca6ff08b23d6f85d2c26af4163ed0759de 100644
--- a/libavcodec/armv4l/dsputil_arm.c
+++ b/libavcodec/armv4l/dsputil_arm.c
@@ -240,9 +240,7 @@ void dsputil_init_armv4l(DSPContext* c, AVCodecContext *avctx)
     c->put_no_rnd_pixels_tab[1][2] = put_no_rnd_pixels8_y2_arm; //OK
 /*     c->put_no_rnd_pixels_tab[1][3] = put_no_rnd_pixels8_xy2_arm;//NG */
 
-#if 1
 #ifdef HAVE_IWMMXT
     dsputil_init_iwmmxt(c, avctx);
 #endif
-#endif
 }
diff --git a/libavcodec/armv4l/dsputil_iwmmxt.c b/libavcodec/armv4l/dsputil_iwmmxt.c
index 6e2465d7c8e460b4a3411f94f3032749f7cc23b0..99a55e79053ade2937435f5e52c5de4f44cbff10 100644
--- a/libavcodec/armv4l/dsputil_iwmmxt.c
+++ b/libavcodec/armv4l/dsputil_iwmmxt.c
@@ -126,8 +126,26 @@ static void nop(uint8_t *block, const uint8_t *pixels, int line_size, int h)
     return;
 }
 
+int mm_flags; /* multimedia extension flags */
+
+int mm_support(void)
+{
+    return 0; /* TODO, implement proper detection */
+}
+
 void dsputil_init_iwmmxt(DSPContext* c, AVCodecContext *avctx)
 {
+    mm_flags = mm_support();
+
+    if (avctx->dsp_mask) {
+	if (avctx->dsp_mask & FF_MM_FORCE)
+	    mm_flags |= (avctx->dsp_mask & 0xffff);
+	else
+	    mm_flags &= ~(avctx->dsp_mask & 0xffff);
+    }
+
+    if (!(mm_flags & MM_IWMMXT)) return;
+
     c->add_pixels_clamped = add_pixels_clamped_iwmmxt;
 
     c->put_pixels_tab[0][0] = put_pixels16_iwmmxt;
diff --git a/libavcodec/armv4l/mpegvideo_iwmmxt.c b/libavcodec/armv4l/mpegvideo_iwmmxt.c
index 0f4c99e3ac8c6627cdf3d36bcacfd6cd3e2c09fb..9724de8c4c153fa79096cc91b515af5f2f247e6a 100644
--- a/libavcodec/armv4l/mpegvideo_iwmmxt.c
+++ b/libavcodec/armv4l/mpegvideo_iwmmxt.c
@@ -90,6 +90,8 @@ static void dct_unquantize_h263_inter_iwmmxt(MpegEncContext *s,
 
 void MPV_common_init_iwmmxt(MpegEncContext *s)
 {
+    if (!(mm_flags & MM_IWMMXT)) return;
+
     s->dct_unquantize_h263_intra = dct_unquantize_h263_intra_iwmmxt;
 #if 0
     s->dct_unquantize_h263_inter = dct_unquantize_h263_inter_iwmmxt;
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 6f644f64935bfd9d71fd0692abc36be26b2a7d60..c6ebbb190d0e4b8bf69f8d97a8ab4d42939ac576 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -17,7 +17,7 @@ extern "C" {
 
 #define FFMPEG_VERSION_INT     0x000409
 #define FFMPEG_VERSION         "0.4.9-pre1"
-#define LIBAVCODEC_BUILD       4756
+#define LIBAVCODEC_BUILD       4757
 
 #define LIBAVCODEC_VERSION_INT FFMPEG_VERSION_INT
 #define LIBAVCODEC_VERSION     FFMPEG_VERSION
@@ -1193,7 +1193,7 @@ typedef struct AVCodecContext {
 #define FF_IDCT_SIMPLEARM    10
 #define FF_IDCT_H264         11
 #define FF_IDCT_VP3          12
-#define FP_IDCT_IPP          13
+#define FF_IDCT_IPP          13
 
     /**
      * slice count.
@@ -1236,6 +1236,9 @@ typedef struct AVCodecContext {
 #define FF_MM_SSE2	0x0010 /* PIV SSE2 functions */
 #define FF_MM_3DNOWEXT	0x0020 /* AMD 3DNowExt */
 #endif /* HAVE_MMX */
+#ifdef HAVE_IWMMXT
+#define FF_MM_IWMMXT	0x0100 /* XScale IWMMXT */
+#endif /* HAVE_IWMMXT */
 
     /**
      * bits per sample/pixel from the demuxer (needed for huffyuv).
diff --git a/libavcodec/dsputil.h b/libavcodec/dsputil.h
index b9de38648bf3cb38a671153acffbef54346ec736..cad32660db548b1260a03a242f3e4897b5be7458 100644
--- a/libavcodec/dsputil.h
+++ b/libavcodec/dsputil.h
@@ -432,6 +432,10 @@ void dsputil_init_pix_mmx(DSPContext* c, AVCodecContext *avctx);
 #define __align8 __attribute__ ((aligned (4)))
 #define STRIDE_ALIGN 4
 
+#define MM_IWMMXT    0x0100 /* XScale IWMMXT */
+
+extern int mm_flags;
+
 void dsputil_init_armv4l(DSPContext* c, AVCodecContext *avctx);
 
 #elif defined(HAVE_MLIB)