1/2 resolution decoding

Originally committed as revision 3507 to svn://svn.ffmpeg.org/ffmpeg/trunk

10 files changed, 724 insertions, 73 deletions

diff --git a/ffmpeg.c b/ffmpeg.c
index 1bbf7d7c5d..2c6eab85fb 100644
--- a/ffmpeg.c
+++ b/ffmpeg.c
@@ -188,6 +188,8 @@ static int predictor = 0;
 static int video_profile = FF_PROFILE_UNKNOWN;
 static int video_level = FF_LEVEL_UNKNOWN;
 static int nsse_weight = 8;
+static int subpel_quality= 8;
+static int lowres= 0;
 extern int loop_input; /* currently a hack */
 
 static int gop_size = 12;
@@ -3148,6 +3150,8 @@ static void opt_output_file(const char *filename)
                 video_enc->profile= video_profile;
                 video_enc->level= video_level;
                 video_enc->nsse_weight= nsse_weight;
+                video_enc->me_subpel_quality= subpel_quality;
+                video_enc->lowres= lowres;
 
                 if(packet_size){
                     video_enc->rtp_mode= 1;
@@ -3840,6 +3844,8 @@ const OptionDef options[] = {
     { "vprofile", OPT_INT | HAS_ARG | OPT_EXPERT | OPT_VIDEO, {(void*)&video_profile}, "profile", "" },
     { "vlevel", OPT_INT | HAS_ARG | OPT_EXPERT | OPT_VIDEO, {(void*)&video_level}, "level", "" },
     { "nssew", OPT_INT | HAS_ARG | OPT_EXPERT | OPT_VIDEO, {(void*)&nsse_weight}, "weight", "" },
+    { "subq", OPT_INT | HAS_ARG | OPT_EXPERT | OPT_VIDEO, {(void*)&subpel_quality}, "", "" },
+    { "lowres", OPT_INT | HAS_ARG | OPT_EXPERT | OPT_VIDEO, {(void*)&lowres}, "", "" },
 
     /* audio options */
     { "ab", HAS_ARG | OPT_AUDIO, {(void*)opt_audio_bitrate}, "set audio bitrate (in kbit/s)", "bitrate", },
diff --git a/ffplay.c b/ffplay.c
index ff655f7868..bc0998b226 100644
--- a/ffplay.c
+++ b/ffplay.c
@@ -171,6 +171,8 @@ static int step = 0;
 static int thread_count = 1;
 static int workaround_bugs = 1;
 static int fast = 0;
+static int lowres = 0;
+static int idct = FF_IDCT_AUTO;
 
 /* current context */
 static int is_full_screen;
@@ -1173,6 +1175,8 @@ static int stream_component_open(VideoState *is, int stream_index)
     enc->debug_mv = debug_mv;
     enc->debug = debug;
     enc->workaround_bugs = workaround_bugs;
+    enc->lowres = lowres;
+    enc->idct_algo= idct;
     if(fast) enc->flags2 |= CODEC_FLAG2_FAST;
     if (!codec ||
         avcodec_open(enc, codec) < 0)
@@ -1832,6 +1836,8 @@ const OptionDef options[] = {
     { "bug", OPT_INT | HAS_ARG | OPT_EXPERT, {(void*)&workaround_bugs}, "workaround bugs", "" },
     { "vismv", HAS_ARG | OPT_EXPERT, {(void*)opt_vismv}, "visualize motion vectors", "" },
     { "fast", OPT_BOOL | OPT_EXPERT, {(void*)&fast}, "non spec compliant optimizations", "" },
+    { "lowres", OPT_INT | HAS_ARG | OPT_EXPERT, {(void*)&lowres}, "", "" },
+    { "idct", OPT_INT | HAS_ARG | OPT_EXPERT, {(void*)&idct}, "set idct algo",  "algo" },
 #ifdef CONFIG_NETWORK
     { "rtp_tcp", OPT_EXPERT, {(void*)&opt_rtp_tcp}, "force RTP/TCP protocol usage", "" },
 #endif
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index dc83bba064..87bfa02194 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       4721
+#define LIBAVCODEC_BUILD       4722
 
 #define LIBAVCODEC_VERSION_INT FFMPEG_VERSION_INT
 #define LIBAVCODEC_VERSION     FFMPEG_VERSION
@@ -1111,6 +1111,7 @@ typedef struct AVCodecContext {
 #define FF_IDCT_ALTIVEC      8
 #define FF_IDCT_SH4          9
 #define FF_IDCT_SIMPLEARM    10
+#define FF_IDCT_INT4         11
 
     /**
      * slice count.
@@ -1656,6 +1657,13 @@ typedef struct AVCodecContext {
      */
      int level;
 #define FF_LEVEL_UNKNOWN -99
+
+    /**
+     * low resolution decoding. 1-> 1/2 size, 2->1/4 size
+     * - encoding: unused
+     * - decoding: set by user
+     */
+     int lowres;
 } AVCodecContext;
 
 
diff --git a/libavcodec/dsputil.c b/libavcodec/dsputil.c
index a2ef9f6d7f..8b95ff2e6c 100644
--- a/libavcodec/dsputil.c
+++ b/libavcodec/dsputil.c
@@ -446,6 +446,24 @@ static void put_pixels_clamped_c(const DCTELEM *block, uint8_t *restrict pixels,
     }
 }
 
+static void put_pixels_clamped4_c(const DCTELEM *block, uint8_t *restrict pixels,
+				 int line_size)
+{
+    int i;
+    uint8_t *cm = cropTbl + MAX_NEG_CROP;
+    
+    /* read the pixels */
+    for(i=0;i<4;i++) {
+        pixels[0] = cm[block[0]];
+        pixels[1] = cm[block[1]];
+        pixels[2] = cm[block[2]];
+        pixels[3] = cm[block[3]];
+
+        pixels += line_size;
+        block += 8;
+    }
+}
+
 static void put_signed_pixels_clamped_c(const DCTELEM *block, 
                                         uint8_t *restrict pixels,
                                         int line_size)
@@ -487,6 +505,23 @@ static void add_pixels_clamped_c(const DCTELEM *block, uint8_t *restrict pixels,
         block += 8;
     }
 }
+
+static void add_pixels_clamped4_c(const DCTELEM *block, uint8_t *restrict pixels,
+                          int line_size)
+{
+    int i;
+    uint8_t *cm = cropTbl + MAX_NEG_CROP;
+    
+    /* read the pixels */
+    for(i=0;i<4;i++) {
+        pixels[0] = cm[pixels[0] + block[0]];
+        pixels[1] = cm[pixels[1] + block[1]];
+        pixels[2] = cm[pixels[2] + block[2]];
+        pixels[3] = cm[pixels[3] + block[3]];
+        pixels += line_size;
+        block += 8;
+    }
+}
 #if 0
 
 #define PIXOP2(OPNAME, OP) \
@@ -3294,6 +3329,17 @@ static void ff_jref_idct_add(uint8_t *dest, int line_size, DCTELEM *block)
     add_pixels_clamped_c(block, dest, line_size);
 }
 
+static void ff_jref_idct4_put(uint8_t *dest, int line_size, DCTELEM *block)
+{
+    j_rev_dct4 (block);
+    put_pixels_clamped4_c(block, dest, line_size);
+}
+static void ff_jref_idct4_add(uint8_t *dest, int line_size, DCTELEM *block)
+{
+    j_rev_dct4 (block);
+    add_pixels_clamped4_c(block, dest, line_size);
+}
+
 /* init static data */
 void dsputil_static_init(void)
 {
@@ -3332,16 +3378,23 @@ void dsputil_init(DSPContext* c, AVCodecContext *avctx)
     }
 #endif //CONFIG_ENCODERS
 
-    if(avctx->idct_algo==FF_IDCT_INT){
-        c->idct_put= ff_jref_idct_put;
-        c->idct_add= ff_jref_idct_add;
-        c->idct    = j_rev_dct;
-        c->idct_permutation_type= FF_LIBMPEG2_IDCT_PERM;
-    }else{ //accurate/default
-        c->idct_put= simple_idct_put;
-        c->idct_add= simple_idct_add;
-        c->idct    = simple_idct;
+    if(avctx->lowres==1){
+        c->idct_put= ff_jref_idct4_put;
+        c->idct_add= ff_jref_idct4_add;
+        c->idct    = j_rev_dct4;
         c->idct_permutation_type= FF_NO_IDCT_PERM;
+    }else{
+        if(avctx->idct_algo==FF_IDCT_INT){
+            c->idct_put= ff_jref_idct_put;
+            c->idct_add= ff_jref_idct_add;
+            c->idct    = j_rev_dct;
+            c->idct_permutation_type= FF_LIBMPEG2_IDCT_PERM;
+        }else{ //accurate/default
+            c->idct_put= simple_idct_put;
+            c->idct_add= simple_idct_add;
+            c->idct    = simple_idct;
+            c->idct_permutation_type= FF_NO_IDCT_PERM;
+        }
     }
 
     /* VP3 DSP support */
diff --git a/libavcodec/dsputil.h b/libavcodec/dsputil.h
index 5aaa94c3ce..8dcc5d910d 100644
--- a/libavcodec/dsputil.h
+++ b/libavcodec/dsputil.h
@@ -42,6 +42,7 @@ void ff_jpeg_fdct_islow (DCTELEM *data);
 void ff_fdct248_islow (DCTELEM *data);
 
 void j_rev_dct (DCTELEM *data);
+void j_rev_dct4 (DCTELEM *data);
 
 void ff_fdct_mmx(DCTELEM *block);
 void ff_fdct_mmx2(DCTELEM *block);
diff --git a/libavcodec/i386/dsputil_mmx.c b/libavcodec/i386/dsputil_mmx.c
index fcdd426d36..4d19e66f37 100644
--- a/libavcodec/i386/dsputil_mmx.c
+++ b/libavcodec/i386/dsputil_mmx.c
@@ -2984,23 +2984,24 @@ void dsputil_init_mmx(DSPContext* c, AVCodecContext *avctx)
             }
         }
 #endif //CONFIG_ENCODERS
-
-        if(idct_algo==FF_IDCT_AUTO || idct_algo==FF_IDCT_SIMPLEMMX){
-            c->idct_put= ff_simple_idct_put_mmx;
-            c->idct_add= ff_simple_idct_add_mmx;
-            c->idct    = ff_simple_idct_mmx;
-            c->idct_permutation_type= FF_SIMPLE_IDCT_PERM;
-        }else if(idct_algo==FF_IDCT_LIBMPEG2MMX){
-            if(mm_flags & MM_MMXEXT){
-                c->idct_put= ff_libmpeg2mmx2_idct_put;
-                c->idct_add= ff_libmpeg2mmx2_idct_add;
-                c->idct    = ff_mmxext_idct;
-            }else{
-                c->idct_put= ff_libmpeg2mmx_idct_put;
-                c->idct_add= ff_libmpeg2mmx_idct_add;
-                c->idct    = ff_mmx_idct;
+        if(avctx->lowres==0){
+            if(idct_algo==FF_IDCT_AUTO || idct_algo==FF_IDCT_SIMPLEMMX){
+                c->idct_put= ff_simple_idct_put_mmx;
+                c->idct_add= ff_simple_idct_add_mmx;
+                c->idct    = ff_simple_idct_mmx;
+                c->idct_permutation_type= FF_SIMPLE_IDCT_PERM;
+            }else if(idct_algo==FF_IDCT_LIBMPEG2MMX){
+                if(mm_flags & MM_MMXEXT){
+                    c->idct_put= ff_libmpeg2mmx2_idct_put;
+                    c->idct_add= ff_libmpeg2mmx2_idct_add;
+                    c->idct    = ff_mmxext_idct;
+                }else{
+                    c->idct_put= ff_libmpeg2mmx_idct_put;
+                    c->idct_add= ff_libmpeg2mmx_idct_add;
+                    c->idct    = ff_mmx_idct;
+                }
+                c->idct_permutation_type= FF_LIBMPEG2_IDCT_PERM;
             }
-            c->idct_permutation_type= FF_LIBMPEG2_IDCT_PERM;
         }
 
         /* VP3 optimized DSP functions */
diff --git a/libavcodec/jrevdct.c b/libavcodec/jrevdct.c
index 3bd78c1925..1c253fee39 100644
--- a/libavcodec/jrevdct.c
+++ b/libavcodec/jrevdct.c
@@ -1172,5 +1172,461 @@ void j_rev_dct(DCTBLOCK data)
   }
 }
 
+#undef DCTSIZE
+#define DCTSIZE 4
+#define DCTSTRIDE 8
+
+void j_rev_dct4(DCTBLOCK data)
+{
+  int32_t tmp0, tmp1, tmp2, tmp3;
+  int32_t tmp10, tmp11, tmp12, tmp13;
+  int32_t z1;
+  int32_t d0, d2, d4, d6;
+  register DCTELEM *dataptr;
+  int rowctr;
+   
+  /* Pass 1: process rows. */
+  /* Note results are scaled up by sqrt(8) compared to a true IDCT; */
+  /* furthermore, we scale the results by 2**PASS1_BITS. */
+
+  dataptr = data;
+
+  for (rowctr = DCTSIZE-1; rowctr >= 0; rowctr--) {
+    /* Due to quantization, we will usually find that many of the input
+     * coefficients are zero, especially the AC terms.  We can exploit this
+     * by short-circuiting the IDCT calculation for any row in which all
+     * the AC terms are zero.  In that case each output is equal to the
+     * DC coefficient (with scale factor as needed).
+     * With typical images and quantization tables, half or more of the
+     * row DCT calculations can be simplified this way.
+     */
+
+    register int *idataptr = (int*)dataptr;
+
+    /* WARNING: we do the same permutation as MMX idct to simplify the
+       video core */
+    d0 = dataptr[0];
+    d2 = dataptr[1];
+    d4 = dataptr[2];
+    d6 = dataptr[3];
+
+    if ((d2 | d4 | d6) == 0) {
+      /* AC terms all zero */
+      if (d0) {
+	  /* Compute a 32 bit value to assign. */
+	  DCTELEM dcval = (DCTELEM) (d0 << PASS1_BITS);
+	  register int v = (dcval & 0xffff) | ((dcval << 16) & 0xffff0000);
+	  
+	  idataptr[0] = v;
+	  idataptr[1] = v;
+      }
+      
+      dataptr += DCTSTRIDE;	/* advance pointer to next row */
+      continue;
+    }
+
+    /* Even part: reverse the even part of the forward DCT. */
+    /* The rotator is sqrt(2)*c(-6). */
+    if (d6) {
+	if (d4) {
+	    if (d2) {
+		if (d0) {
+		    /* d0 != 0, d2 != 0, d4 != 0, d6 != 0 */
+		    z1 = MULTIPLY(d2 + d6, FIX_0_541196100);
+		    tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065);
+		    tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865);
+
+		    tmp0 = (d0 + d4) << CONST_BITS;
+		    tmp1 = (d0 - d4) << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp1 + tmp2;
+		    tmp12 = tmp1 - tmp2;
+		} else {
+		    /* d0 == 0, d2 != 0, d4 != 0, d6 != 0 */
+		    z1 = MULTIPLY(d2 + d6, FIX_0_541196100);
+		    tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065);
+		    tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865);
+
+		    tmp0 = d4 << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp2 - tmp0;
+		    tmp12 = -(tmp0 + tmp2);
+		}
+	    } else {
+		if (d0) {
+		    /* d0 != 0, d2 == 0, d4 != 0, d6 != 0 */
+		    tmp2 = MULTIPLY(-d6, FIX_1_306562965);
+		    tmp3 = MULTIPLY(d6, FIX_0_541196100);
+
+		    tmp0 = (d0 + d4) << CONST_BITS;
+		    tmp1 = (d0 - d4) << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp1 + tmp2;
+		    tmp12 = tmp1 - tmp2;
+		} else {
+		    /* d0 == 0, d2 == 0, d4 != 0, d6 != 0 */
+		    tmp2 = MULTIPLY(-d6, FIX_1_306562965);
+		    tmp3 = MULTIPLY(d6, FIX_0_541196100);
+
+		    tmp0 = d4 << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp2 - tmp0;
+		    tmp12 = -(tmp0 + tmp2);
+		}
+	    }
+	} else {
+	    if (d2) {
+		if (d0) {
+		    /* d0 != 0, d2 != 0, d4 == 0, d6 != 0 */
+		    z1 = MULTIPLY(d2 + d6, FIX_0_541196100);
+		    tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065);
+		    tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865);
+
+		    tmp0 = d0 << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp0 + tmp2;
+		    tmp12 = tmp0 - tmp2;
+		} else {
+		    /* d0 == 0, d2 != 0, d4 == 0, d6 != 0 */
+		    z1 = MULTIPLY(d2 + d6, FIX_0_541196100);
+		    tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065);
+		    tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865);
+
+		    tmp10 = tmp3;
+		    tmp13 = -tmp3;
+		    tmp11 = tmp2;
+		    tmp12 = -tmp2;
+		}
+	    } else {
+		if (d0) {
+		    /* d0 != 0, d2 == 0, d4 == 0, d6 != 0 */
+		    tmp2 = MULTIPLY(-d6, FIX_1_306562965);
+		    tmp3 = MULTIPLY(d6, FIX_0_541196100);
+
+		    tmp0 = d0 << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp0 + tmp2;
+		    tmp12 = tmp0 - tmp2;
+		} else {
+		    /* d0 == 0, d2 == 0, d4 == 0, d6 != 0 */
+		    tmp2 = MULTIPLY(-d6, FIX_1_306562965);
+		    tmp3 = MULTIPLY(d6, FIX_0_541196100);
+
+		    tmp10 = tmp3;
+		    tmp13 = -tmp3;
+		    tmp11 = tmp2;
+		    tmp12 = -tmp2;
+		}
+	    }
+	}
+    } else {
+	if (d4) {
+	    if (d2) {
+		if (d0) {
+		    /* d0 != 0, d2 != 0, d4 != 0, d6 == 0 */
+		    tmp2 = MULTIPLY(d2, FIX_0_541196100);
+		    tmp3 = MULTIPLY(d2, FIX_1_306562965);
+
+		    tmp0 = (d0 + d4) << CONST_BITS;
+		    tmp1 = (d0 - d4) << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp1 + tmp2;
+		    tmp12 = tmp1 - tmp2;
+		} else {
+		    /* d0 == 0, d2 != 0, d4 != 0, d6 == 0 */
+		    tmp2 = MULTIPLY(d2, FIX_0_541196100);
+		    tmp3 = MULTIPLY(d2, FIX_1_306562965);
+
+		    tmp0 = d4 << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp2 - tmp0;
+		    tmp12 = -(tmp0 + tmp2);
+		}
+	    } else {
+		if (d0) {
+		    /* d0 != 0, d2 == 0, d4 != 0, d6 == 0 */
+		    tmp10 = tmp13 = (d0 + d4) << CONST_BITS;
+		    tmp11 = tmp12 = (d0 - d4) << CONST_BITS;
+		} else {
+		    /* d0 == 0, d2 == 0, d4 != 0, d6 == 0 */
+		    tmp10 = tmp13 = d4 << CONST_BITS;
+		    tmp11 = tmp12 = -tmp10;
+		}
+	    }
+	} else {
+	    if (d2) {
+		if (d0) {
+		    /* d0 != 0, d2 != 0, d4 == 0, d6 == 0 */
+		    tmp2 = MULTIPLY(d2, FIX_0_541196100);
+		    tmp3 = MULTIPLY(d2, FIX_1_306562965);
+
+		    tmp0 = d0 << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp0 + tmp2;
+		    tmp12 = tmp0 - tmp2;
+		} else {
+		    /* d0 == 0, d2 != 0, d4 == 0, d6 == 0 */
+		    tmp2 = MULTIPLY(d2, FIX_0_541196100);
+		    tmp3 = MULTIPLY(d2, FIX_1_306562965);
+
+		    tmp10 = tmp3;
+		    tmp13 = -tmp3;
+		    tmp11 = tmp2;
+		    tmp12 = -tmp2;
+		}
+	    } else {
+		if (d0) {
+		    /* d0 != 0, d2 == 0, d4 == 0, d6 == 0 */
+		    tmp10 = tmp13 = tmp11 = tmp12 = d0 << CONST_BITS;
+		} else {
+		    /* d0 == 0, d2 == 0, d4 == 0, d6 == 0 */
+		    tmp10 = tmp13 = tmp11 = tmp12 = 0;
+		}
+	    }
+	}
+      }
+
+    /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
+
+    dataptr[0] = (DCTELEM) DESCALE(tmp10, CONST_BITS-PASS1_BITS);
+    dataptr[1] = (DCTELEM) DESCALE(tmp11, CONST_BITS-PASS1_BITS);
+    dataptr[2] = (DCTELEM) DESCALE(tmp12, CONST_BITS-PASS1_BITS);
+    dataptr[3] = (DCTELEM) DESCALE(tmp13, CONST_BITS-PASS1_BITS);
+
+    dataptr += DCTSTRIDE;		/* advance pointer to next row */
+  }
+
+  /* Pass 2: process columns. */
+  /* Note that we must descale the results by a factor of 8 == 2**3, */
+  /* and also undo the PASS1_BITS scaling. */
+
+  dataptr = data;
+  for (rowctr = DCTSIZE-1; rowctr >= 0; rowctr--) {
+    /* Columns of zeroes can be exploited in the same way as we did with rows.
+     * However, the row calculation has created many nonzero AC terms, so the
+     * simplification applies less often (typically 5% to 10% of the time).
+     * On machines with very fast multiplication, it's possible that the
+     * test takes more time than it's worth.  In that case this section
+     * may be commented out.
+     */
+
+    d0 = dataptr[DCTSTRIDE*0];
+    d2 = dataptr[DCTSTRIDE*1];
+    d4 = dataptr[DCTSTRIDE*2];
+    d6 = dataptr[DCTSTRIDE*3];
+
+    /* Even part: reverse the even part of the forward DCT. */
+    /* The rotator is sqrt(2)*c(-6). */
+    if (d6) {
+	if (d4) {
+	    if (d2) {
+		if (d0) {
+		    /* d0 != 0, d2 != 0, d4 != 0, d6 != 0 */
+		    z1 = MULTIPLY(d2 + d6, FIX_0_541196100);
+		    tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065);
+		    tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865);
+
+		    tmp0 = (d0 + d4) << CONST_BITS;
+		    tmp1 = (d0 - d4) << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp1 + tmp2;
+		    tmp12 = tmp1 - tmp2;
+		} else {
+		    /* d0 == 0, d2 != 0, d4 != 0, d6 != 0 */
+		    z1 = MULTIPLY(d2 + d6, FIX_0_541196100);
+		    tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065);
+		    tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865);
+
+		    tmp0 = d4 << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp2 - tmp0;
+		    tmp12 = -(tmp0 + tmp2);
+		}
+	    } else {
+		if (d0) {
+		    /* d0 != 0, d2 == 0, d4 != 0, d6 != 0 */
+		    tmp2 = MULTIPLY(-d6, FIX_1_306562965);
+		    tmp3 = MULTIPLY(d6, FIX_0_541196100);
+
+		    tmp0 = (d0 + d4) << CONST_BITS;
+		    tmp1 = (d0 - d4) << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp1 + tmp2;
+		    tmp12 = tmp1 - tmp2;
+		} else {
+		    /* d0 == 0, d2 == 0, d4 != 0, d6 != 0 */
+		    tmp2 = MULTIPLY(-d6, FIX_1_306562965);
+		    tmp3 = MULTIPLY(d6, FIX_0_541196100);
+
+		    tmp0 = d4 << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp2 - tmp0;
+		    tmp12 = -(tmp0 + tmp2);
+		}
+	    }
+	} else {
+	    if (d2) {
+		if (d0) {
+		    /* d0 != 0, d2 != 0, d4 == 0, d6 != 0 */
+		    z1 = MULTIPLY(d2 + d6, FIX_0_541196100);
+		    tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065);
+		    tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865);
+
+		    tmp0 = d0 << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp0 + tmp2;
+		    tmp12 = tmp0 - tmp2;
+		} else {
+		    /* d0 == 0, d2 != 0, d4 == 0, d6 != 0 */
+		    z1 = MULTIPLY(d2 + d6, FIX_0_541196100);
+		    tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065);
+		    tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865);
+
+		    tmp10 = tmp3;
+		    tmp13 = -tmp3;
+		    tmp11 = tmp2;
+		    tmp12 = -tmp2;
+		}
+	    } else {
+		if (d0) {
+		    /* d0 != 0, d2 == 0, d4 == 0, d6 != 0 */
+		    tmp2 = MULTIPLY(-d6, FIX_1_306562965);
+		    tmp3 = MULTIPLY(d6, FIX_0_541196100);
+
+		    tmp0 = d0 << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp0 + tmp2;
+		    tmp12 = tmp0 - tmp2;
+		} else {
+		    /* d0 == 0, d2 == 0, d4 == 0, d6 != 0 */
+		    tmp2 = MULTIPLY(-d6, FIX_1_306562965);
+		    tmp3 = MULTIPLY(d6, FIX_0_541196100);
+
+		    tmp10 = tmp3;
+		    tmp13 = -tmp3;
+		    tmp11 = tmp2;
+		    tmp12 = -tmp2;
+		}
+	    }
+	}
+    } else {
+	if (d4) {
+	    if (d2) {
+		if (d0) {
+		    /* d0 != 0, d2 != 0, d4 != 0, d6 == 0 */
+		    tmp2 = MULTIPLY(d2, FIX_0_541196100);
+		    tmp3 = MULTIPLY(d2, FIX_1_306562965);
+
+		    tmp0 = (d0 + d4) << CONST_BITS;
+		    tmp1 = (d0 - d4) << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp1 + tmp2;
+		    tmp12 = tmp1 - tmp2;
+		} else {
+		    /* d0 == 0, d2 != 0, d4 != 0, d6 == 0 */
+		    tmp2 = MULTIPLY(d2, FIX_0_541196100);
+		    tmp3 = MULTIPLY(d2, FIX_1_306562965);
+
+		    tmp0 = d4 << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp2 - tmp0;
+		    tmp12 = -(tmp0 + tmp2);
+		}
+	    } else {
+		if (d0) {
+		    /* d0 != 0, d2 == 0, d4 != 0, d6 == 0 */
+		    tmp10 = tmp13 = (d0 + d4) << CONST_BITS;
+		    tmp11 = tmp12 = (d0 - d4) << CONST_BITS;
+		} else {
+		    /* d0 == 0, d2 == 0, d4 != 0, d6 == 0 */
+		    tmp10 = tmp13 = d4 << CONST_BITS;
+		    tmp11 = tmp12 = -tmp10;
+		}
+	    }
+	} else {
+	    if (d2) {
+		if (d0) {
+		    /* d0 != 0, d2 != 0, d4 == 0, d6 == 0 */
+		    tmp2 = MULTIPLY(d2, FIX_0_541196100);
+		    tmp3 = MULTIPLY(d2, FIX_1_306562965);
+
+		    tmp0 = d0 << CONST_BITS;
+
+		    tmp10 = tmp0 + tmp3;
+		    tmp13 = tmp0 - tmp3;
+		    tmp11 = tmp0 + tmp2;
+		    tmp12 = tmp0 - tmp2;
+		} else {
+		    /* d0 == 0, d2 != 0, d4 == 0, d6 == 0 */
+		    tmp2 = MULTIPLY(d2, FIX_0_541196100);
+		    tmp3 = MULTIPLY(d2, FIX_1_306562965);
+
+		    tmp10 = tmp3;
+		    tmp13 = -tmp3;
+		    tmp11 = tmp2;
+		    tmp12 = -tmp2;
+		}
+	    } else {
+		if (d0) {
+		    /* d0 != 0, d2 == 0, d4 == 0, d6 == 0 */
+		    tmp10 = tmp13 = tmp11 = tmp12 = d0 << CONST_BITS;
+		} else {
+		    /* d0 == 0, d2 == 0, d4 == 0, d6 == 0 */
+		    tmp10 = tmp13 = tmp11 = tmp12 = 0;
+		}
+	    }
+	}
+    }
+
+    /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
+
+    dataptr[DCTSTRIDE*0] = (DCTELEM) DESCALE(tmp10,
+					   CONST_BITS+PASS1_BITS+3);
+    dataptr[DCTSTRIDE*1] = (DCTELEM) DESCALE(tmp11,
+					   CONST_BITS+PASS1_BITS+3);
+    dataptr[DCTSTRIDE*2] = (DCTELEM) DESCALE(tmp12,
+					   CONST_BITS+PASS1_BITS+3);
+    dataptr[DCTSTRIDE*3] = (DCTELEM) DESCALE(tmp13,
+					   CONST_BITS+PASS1_BITS+3);
+    
+    dataptr++;			/* advance pointer to next column */
+  }
+}
+
+
 #undef FIX
 #undef CONST_BITS
diff --git a/libavcodec/mpeg12.c b/libavcodec/mpeg12.c
index 7a76d55c66..484f6b278e 100644
--- a/libavcodec/mpeg12.c
+++ b/libavcodec/mpeg12.c
@@ -2409,6 +2409,7 @@ static int mpeg_decode_slice(Mpeg1Context *s1, int mb_y,
     AVCodecContext *avctx= s->avctx;
     int ret;
     const int field_pic= s->picture_structure != PICT_FRAME;
+    const int lowres= s->avctx->lowres;
 
     s->resync_mb_x=
     s->resync_mb_y= -1;
@@ -2518,9 +2519,9 @@ static int mpeg_decode_slice(Mpeg1Context *s1, int mb_y,
             }
         }
 
-        s->dest[0] += 16;
-        s->dest[1] += 16 >> s->chroma_x_shift;
-        s->dest[2] += 16 >> s->chroma_x_shift;
+        s->dest[0] += 16 >> lowres;
+        s->dest[1] += 16 >> (s->chroma_x_shift + lowres);
+        s->dest[2] += 16 >> (s->chroma_x_shift + lowres);
 
         MPV_decode_mb(s, s->block);
         
diff --git a/libavcodec/mpegvideo.c b/libavcodec/mpegvideo.c
index b3faf830a9..c1685760dc 100644
--- a/libavcodec/mpegvideo.c
+++ b/libavcodec/mpegvideo.c
@@ -2607,6 +2607,82 @@ if(s->quarter_sample)
         pix_op[s->chroma_x_shift][uvdxy](dest_cr, ptr_cr, uvlinesize, h >> s->chroma_y_shift);
     }
 }
+
+/* apply one mpeg motion vector to the three components */
+static always_inline void mpeg_motion_lowres(MpegEncContext *s,
+                               uint8_t *dest_y, uint8_t *dest_cb, uint8_t *dest_cr,
+                               int field_based, int bottom_field, int field_select,
+                               uint8_t **ref_picture, h264_chroma_mc_func *pix_op,
+                               int motion_x, int motion_y, int h)
+{
+    uint8_t *ptr_y, *ptr_cb, *ptr_cr;
+    int mx, my, src_x, src_y, uvsrc_x, uvsrc_y, uvlinesize, linesize, sx, sy, uvsx, uvsy;
+    const int lowres= s->avctx->lowres;
+    const int block_s= 8>>lowres;
+    const int s_mask= (2<<lowres)-1;
+    const int h_edge_pos = s->h_edge_pos >> lowres;
+    const int v_edge_pos = s->v_edge_pos >> lowres;
+    linesize   = s->current_picture.linesize[0] << field_based;
+    uvlinesize = s->current_picture.linesize[1] << field_based;
+
+    sx= motion_x & s_mask;
+    sy= motion_y & s_mask;
+    src_x = s->mb_x*2*block_s               + (motion_x >> (lowres+1));
+    src_y = s->mb_y*2*block_s               + (motion_y >> (lowres+1));
+    
+    if (s->out_format == FMT_H263) {
+        uvsx = sx | ((motion_x & 2)>>1);
+        uvsy = sy | ((motion_y & 2)>>1);
+        uvsrc_x = src_x>>1;
+        uvsrc_y = src_y>>1;
+    }else if(s->out_format == FMT_H261){//even chroma mv's are full pel in H261
+        mx = motion_x / 4;
+        my = motion_y / 4;
+        uvsx = (2*mx) & s_mask;
+        uvsy = (2*my) & s_mask;
+        uvsrc_x = s->mb_x*block_s               + (mx >> lowres);
+        uvsrc_y = s->mb_y*block_s               + (my >> lowres);
+    } else {
+        mx = motion_x / 2;
+        my = motion_y / 2;
+        uvsx = mx & s_mask;
+        uvsy = my & s_mask;
+        uvsrc_x = s->mb_x*block_s               + (mx >> (lowres+1));
+        uvsrc_y = s->mb_y*block_s               + (my >> (lowres+1));
+    }
+
+    ptr_y  = ref_picture[0] + src_y * linesize + src_x;
+    ptr_cb = ref_picture[1] + uvsrc_y * uvlinesize + uvsrc_x;
+    ptr_cr = ref_picture[2] + uvsrc_y * uvlinesize + uvsrc_x;
+
+    if(   (unsigned)src_x > h_edge_pos                 - (!!sx) - 2*block_s
+       || (unsigned)src_y >(v_edge_pos >> field_based) - (!!sy) - h){
+            ff_emulated_edge_mc(s->edge_emu_buffer, ptr_y, s->linesize, 17, 17+field_based,
+                             src_x, src_y<<field_based, h_edge_pos, v_edge_pos);
+            ptr_y = s->edge_emu_buffer;
+            if(!(s->flags&CODEC_FLAG_GRAY)){
+                uint8_t *uvbuf= s->edge_emu_buffer+18*s->linesize;
+                ff_emulated_edge_mc(uvbuf  , ptr_cb, s->uvlinesize, 9, 9+field_based, 
+                                 uvsrc_x, uvsrc_y<<field_based, h_edge_pos>>1, v_edge_pos>>1);
+                ff_emulated_edge_mc(uvbuf+16, ptr_cr, s->uvlinesize, 9, 9+field_based, 
+                                 uvsrc_x, uvsrc_y<<field_based, h_edge_pos>>1, v_edge_pos>>1);
+                ptr_cb= uvbuf;
+                ptr_cr= uvbuf+16;
+            }
+    }
+
+    sx <<= 2 - lowres;
+    sy <<= 2 - lowres;
+    pix_op[lowres-1](dest_y, ptr_y, linesize, h, sx, sy);
+    
+    if(!(s->flags&CODEC_FLAG_GRAY)){
+        uvsx <<= 2 - lowres;
+        uvsy <<= 2 - lowres;
+        pix_op[lowres](dest_cb, ptr_cb, uvlinesize, h >> s->chroma_y_shift, uvsx, uvsy);
+        pix_op[lowres](dest_cr, ptr_cr, uvlinesize, h >> s->chroma_y_shift, uvsx, uvsy);
+    }
+}
+
 //FIXME move to dsputil, avg variant, 16x16 version
 static inline void put_obmc(uint8_t *dst, uint8_t *src[5], int stride){
     int x;
@@ -3085,6 +3161,28 @@ static inline void MPV_motion(MpegEncContext *s,
     }
 }
 
+/**
+ * motion compesation of a single macroblock
+ * @param s context
+ * @param dest_y luma destination pointer
+ * @param dest_cb chroma cb/u destination pointer
+ * @param dest_cr chroma cr/v destination pointer
+ * @param dir direction (0->forward, 1->backward)
+ * @param ref_picture array[3] of pointers to the 3 planes of the reference picture
+ * @param pic_op halfpel motion compensation function (average or put normally)
+ * the motion vectors are taken from s->mv and the MV type from s->mv_type
+ */
+static inline void MPV_motion_lowres(MpegEncContext *s, 
+                              uint8_t *dest_y, uint8_t *dest_cb, uint8_t *dest_cr,
+                              int dir, uint8_t **ref_picture, 
+                              h264_chroma_mc_func *pix_op)
+{
+    assert(s->mv_type == MV_TYPE_16X16);
+    mpeg_motion_lowres(s, dest_y, dest_cb, dest_cr, 
+                0, 0, 0,
+                ref_picture, pix_op,
+                s->mv[dir][0][0], s->mv[dir][0][1], 16>>s->avctx->lowres);
+}
 
 /* put block[] to dest[] */
 static inline void put_dct(MpegEncContext *s, 
@@ -3156,7 +3254,7 @@ void ff_clean_intra_table_entries(MpegEncContext *s)
    s->mv       : motion vector
    s->interlaced_dct : true if interlaced dct used (mpeg2)
  */
-void MPV_decode_mb(MpegEncContext *s, DCTELEM block[12][64])
+static always_inline void MPV_decode_mb_internal(MpegEncContext *s, DCTELEM block[12][64], int lowres_flag)
 {
     int mb_x, mb_y;
     const int mb_xy = s->mb_y * s->mb_stride + s->mb_x;
@@ -3202,7 +3300,8 @@ void MPV_decode_mb(MpegEncContext *s, DCTELEM block[12][64])
         qpel_mc_func (*op_qpix)[16];
         const int linesize= s->current_picture.linesize[0]; //not s->linesize as this woulnd be wrong for field pics
         const int uvlinesize= s->current_picture.linesize[1];
-        const int readable= s->pict_type != B_TYPE || s->encoding || s->avctx->draw_horiz_band;
+        const int readable= s->pict_type != B_TYPE || s->encoding || s->avctx->draw_horiz_band || lowres_flag;
+        const int block_size= lowres_flag ? 8>>s->avctx->lowres : 8;
 
         /* avoid copy if macroblock skipped in last frame too */
         /* skip only during decoding as we might trash the buffers during encoding a bit */
@@ -3230,10 +3329,10 @@ void MPV_decode_mb(MpegEncContext *s, DCTELEM block[12][64])
                 *mbskip_ptr = 0; /* not skipped */
             }
         }
-
+        
         dct_linesize = linesize << s->interlaced_dct;
-        dct_offset =(s->interlaced_dct)? linesize : linesize*8;
-
+        dct_offset =(s->interlaced_dct)? linesize : linesize*block_size;
+        
         if(readable){
             dest_y=  s->dest[0];
             dest_cb= s->dest[1];
@@ -3243,25 +3342,37 @@ void MPV_decode_mb(MpegEncContext *s, DCTELEM block[12][64])
             dest_cb= s->b_scratchpad+16*linesize;
             dest_cr= s->b_scratchpad+32*linesize;
         }
+
         if (!s->mb_intra) {
             /* motion handling */
             /* decoding or more than one mb_type (MC was allready done otherwise) */
             if(!s->encoding){
-                if ((!s->no_rounding) || s->pict_type==B_TYPE){                
-		    op_pix = s->dsp.put_pixels_tab;
-                    op_qpix= s->dsp.put_qpel_pixels_tab;
-                }else{
-                    op_pix = s->dsp.put_no_rnd_pixels_tab;
-                    op_qpix= s->dsp.put_no_rnd_qpel_pixels_tab;
-                }
+                if(lowres_flag){
+                    h264_chroma_mc_func *op_pix = s->dsp.put_h264_chroma_pixels_tab;
 
-                if (s->mv_dir & MV_DIR_FORWARD) {
-                    MPV_motion(s, dest_y, dest_cb, dest_cr, 0, s->last_picture.data, op_pix, op_qpix);
-		    op_pix = s->dsp.avg_pixels_tab;
-                    op_qpix= s->dsp.avg_qpel_pixels_tab;
-                }
-                if (s->mv_dir & MV_DIR_BACKWARD) {
-                    MPV_motion(s, dest_y, dest_cb, dest_cr, 1, s->next_picture.data, op_pix, op_qpix);
+                    if (s->mv_dir & MV_DIR_FORWARD) {
+                        MPV_motion_lowres(s, dest_y, dest_cb, dest_cr, 0, s->last_picture.data, op_pix);
+                        op_pix = s->dsp.avg_h264_chroma_pixels_tab;
+                    }
+                    if (s->mv_dir & MV_DIR_BACKWARD) {
+                        MPV_motion_lowres(s, dest_y, dest_cb, dest_cr, 1, s->next_picture.data, op_pix);
+                    }
+                }else{
+                    if ((!s->no_rounding) || s->pict_type==B_TYPE){                
+                        op_pix = s->dsp.put_pixels_tab;
+                        op_qpix= s->dsp.put_qpel_pixels_tab;
+                    }else{
+                        op_pix = s->dsp.put_no_rnd_pixels_tab;
+                        op_qpix= s->dsp.put_no_rnd_qpel_pixels_tab;
+                    }
+                    if (s->mv_dir & MV_DIR_FORWARD) {
+                        MPV_motion(s, dest_y, dest_cb, dest_cr, 0, s->last_picture.data, op_pix, op_qpix);
+                        op_pix = s->dsp.avg_pixels_tab;
+                        op_qpix= s->dsp.avg_qpel_pixels_tab;
+                    }
+                    if (s->mv_dir & MV_DIR_BACKWARD) {
+                        MPV_motion(s, dest_y, dest_cb, dest_cr, 1, s->next_picture.data, op_pix, op_qpix);
+                    }
                 }
             }
 
@@ -3271,20 +3382,20 @@ void MPV_decode_mb(MpegEncContext *s, DCTELEM block[12][64])
             /* add dct residue */
             if(s->encoding || !(   s->h263_msmpeg4 || s->codec_id==CODEC_ID_MPEG1VIDEO || s->codec_id==CODEC_ID_MPEG2VIDEO
                                 || (s->codec_id==CODEC_ID_MPEG4 && !s->mpeg_quant))){
-                add_dequant_dct(s, block[0], 0, dest_y, dct_linesize, s->qscale);
-                add_dequant_dct(s, block[1], 1, dest_y + 8, dct_linesize, s->qscale);
-                add_dequant_dct(s, block[2], 2, dest_y + dct_offset, dct_linesize, s->qscale);
-                add_dequant_dct(s, block[3], 3, dest_y + dct_offset + 8, dct_linesize, s->qscale);
+                add_dequant_dct(s, block[0], 0, dest_y                          , dct_linesize, s->qscale);
+                add_dequant_dct(s, block[1], 1, dest_y              + block_size, dct_linesize, s->qscale);
+                add_dequant_dct(s, block[2], 2, dest_y + dct_offset             , dct_linesize, s->qscale);
+                add_dequant_dct(s, block[3], 3, dest_y + dct_offset + block_size, dct_linesize, s->qscale);
 
                 if(!(s->flags&CODEC_FLAG_GRAY)){
                     add_dequant_dct(s, block[4], 4, dest_cb, uvlinesize, s->chroma_qscale);
                     add_dequant_dct(s, block[5], 5, dest_cr, uvlinesize, s->chroma_qscale);
                 }
             } else if(s->codec_id != CODEC_ID_WMV2){
-                add_dct(s, block[0], 0, dest_y, dct_linesize);
-                add_dct(s, block[1], 1, dest_y + 8, dct_linesize);
-                add_dct(s, block[2], 2, dest_y + dct_offset, dct_linesize);
-                add_dct(s, block[3], 3, dest_y + dct_offset + 8, dct_linesize);
+                add_dct(s, block[0], 0, dest_y                          , dct_linesize);
+                add_dct(s, block[1], 1, dest_y              + block_size, dct_linesize);
+                add_dct(s, block[2], 2, dest_y + dct_offset             , dct_linesize);
+                add_dct(s, block[3], 3, dest_y + dct_offset + block_size, dct_linesize);
 
                 if(!(s->flags&CODEC_FLAG_GRAY)){
                     if(s->chroma_y_shift){//Chroma420
@@ -3316,20 +3427,20 @@ void MPV_decode_mb(MpegEncContext *s, DCTELEM block[12][64])
         } else {
             /* dct only in intra block */
             if(s->encoding || !(s->codec_id==CODEC_ID_MPEG1VIDEO || s->codec_id==CODEC_ID_MPEG2VIDEO)){
-                put_dct(s, block[0], 0, dest_y, dct_linesize, s->qscale);
-                put_dct(s, block[1], 1, dest_y + 8, dct_linesize, s->qscale);
-                put_dct(s, block[2], 2, dest_y + dct_offset, dct_linesize, s->qscale);
-                put_dct(s, block[3], 3, dest_y + dct_offset + 8, dct_linesize, s->qscale);
+                put_dct(s, block[0], 0, dest_y                          , dct_linesize, s->qscale);
+                put_dct(s, block[1], 1, dest_y              + block_size, dct_linesize, s->qscale);
+                put_dct(s, block[2], 2, dest_y + dct_offset             , dct_linesize, s->qscale);
+                put_dct(s, block[3], 3, dest_y + dct_offset + block_size, dct_linesize, s->qscale);
 
                 if(!(s->flags&CODEC_FLAG_GRAY)){
                     put_dct(s, block[4], 4, dest_cb, uvlinesize, s->chroma_qscale);
                     put_dct(s, block[5], 5, dest_cr, uvlinesize, s->chroma_qscale);
                 }
             }else{
-                s->dsp.idct_put(dest_y                 , dct_linesize, block[0]);
-                s->dsp.idct_put(dest_y              + 8, dct_linesize, block[1]);
-                s->dsp.idct_put(dest_y + dct_offset    , dct_linesize, block[2]);
-                s->dsp.idct_put(dest_y + dct_offset + 8, dct_linesize, block[3]);
+                s->dsp.idct_put(dest_y                          , dct_linesize, block[0]);
+                s->dsp.idct_put(dest_y              + block_size, dct_linesize, block[1]);
+                s->dsp.idct_put(dest_y + dct_offset             , dct_linesize, block[2]);
+                s->dsp.idct_put(dest_y + dct_offset + block_size, dct_linesize, block[3]);
 
                 if(!(s->flags&CODEC_FLAG_GRAY)){
                     if(s->chroma_y_shift){
@@ -3362,6 +3473,11 @@ void MPV_decode_mb(MpegEncContext *s, DCTELEM block[12][64])
     }
 }
 
+void MPV_decode_mb(MpegEncContext *s, DCTELEM block[12][64]){
+    if(s->avctx->lowres) MPV_decode_mb_internal(s, block, 1);
+    else                  MPV_decode_mb_internal(s, block, 0);
+}
+
 #ifdef CONFIG_ENCODERS
 
 static inline void dct_single_coeff_elimination(MpegEncContext *s, int n, int threshold)
@@ -3492,6 +3608,7 @@ void ff_draw_horiz_band(MpegEncContext *s, int y, int h){
 void ff_init_block_index(MpegEncContext *s){ //FIXME maybe rename
     const int linesize= s->current_picture.linesize[0]; //not s->linesize as this woulnd be wrong for field pics
     const int uvlinesize= s->current_picture.linesize[1];
+    const int mb_size= 4 - s->avctx->lowres;
         
     s->block_index[0]= s->b8_stride*(s->mb_y*2    ) - 2 + s->mb_x*2;
     s->block_index[1]= s->b8_stride*(s->mb_y*2    ) - 1 + s->mb_x*2;
@@ -3501,15 +3618,15 @@ void ff_init_block_index(MpegEncContext *s){ //FIXME maybe rename
     s->block_index[5]= s->mb_stride*(s->mb_y + s->mb_height + 2) + s->b8_stride*s->mb_height*2 + s->mb_x - 1;
     //block_index is not used by mpeg2, so it is not affected by chroma_format
 
-    s->dest[0] = s->current_picture.data[0] + ((s->mb_x - 1) << 4);
-    s->dest[1] = s->current_picture.data[1] + ((s->mb_x - 1) << (4 - s->chroma_x_shift));
-    s->dest[2] = s->current_picture.data[2] + ((s->mb_x - 1) << (4 - s->chroma_x_shift));
+    s->dest[0] = s->current_picture.data[0] + ((s->mb_x - 1) << mb_size);
+    s->dest[1] = s->current_picture.data[1] + ((s->mb_x - 1) << (mb_size - s->chroma_x_shift));
+    s->dest[2] = s->current_picture.data[2] + ((s->mb_x - 1) << (mb_size - s->chroma_x_shift));
 
     if(!(s->pict_type==B_TYPE && s->avctx->draw_horiz_band && s->picture_structure==PICT_FRAME))
     {
-        s->dest[0] += s->mb_y *   linesize << 4;
-        s->dest[1] += s->mb_y * uvlinesize << (4 - s->chroma_y_shift);
-        s->dest[2] += s->mb_y * uvlinesize << (4 - s->chroma_y_shift);
+        s->dest[0] += s->mb_y *   linesize << mb_size;
+        s->dest[1] += s->mb_y * uvlinesize << (mb_size - s->chroma_y_shift);
+        s->dest[2] += s->mb_y * uvlinesize << (mb_size - s->chroma_y_shift);
     }
 }
 
diff --git a/libavcodec/mpegvideo.h b/libavcodec/mpegvideo.h
index 0c317202c1..19aa1bca2e 100644
--- a/libavcodec/mpegvideo.h
+++ b/libavcodec/mpegvideo.h
@@ -773,15 +773,17 @@ extern enum PixelFormat ff_yuv420p_list[2];
 void ff_init_block_index(MpegEncContext *s);
 
 static inline void ff_update_block_index(MpegEncContext *s){
+    const int block_size= 8>>s->avctx->lowres;
+
     s->block_index[0]+=2;
     s->block_index[1]+=2;
     s->block_index[2]+=2;
     s->block_index[3]+=2;
     s->block_index[4]++;
     s->block_index[5]++;
-    s->dest[0]+= 16;
-    s->dest[1]+= 8;
-    s->dest[2]+= 8;
+    s->dest[0]+= 2*block_size;
+    s->dest[1]+= block_size;
+    s->dest[2]+= block_size;
 }
 
 static inline int get_bits_diff(MpegEncContext *s){