diff --git a/configure b/configure
index 6856c96afda8d1ad74e2dcf3a430dc3ef6de78ee..47cfa3b9830c8c1e603b607acd3ac493b33f2d28 100755
--- a/configure
+++ b/configure
@@ -133,6 +133,7 @@ show_help(){
   echo "  --disable-debug          disable debugging symbols"
   echo "  --disable-mpegaudio-hp   faster (but less accurate)"
   echo "                           MPEG audio decoding [default=no]"
+  echo "  --enable-gray            enable full grayscale support (slower color)"
   echo "  --disable-ffmpeg         disable ffmpeg build"
   echo "  --disable-ffserver       disable ffserver build"
   echo "  --disable-ffplay         disable ffplay build"
@@ -615,6 +616,7 @@ CONFIG_LIST='
     v4l2
     x11grab
     zlib
+    gray
 '
 
 THREADS_LIST='
@@ -860,6 +862,7 @@ network="yes"
 optimize="yes"
 protocols="yes"
 vhook="default"
+gray="no"
 
 # build settings
 SHFLAGS='-shared -Wl,-soname,$@'
diff --git a/libavcodec/mpegvideo.c b/libavcodec/mpegvideo.c
index 49ae03976d396919bd89e11b3452ebb957493aa0..8d5ab11630c8d8bfd352fa1409ea618e45993d57 100644
--- a/libavcodec/mpegvideo.c
+++ b/libavcodec/mpegvideo.c
@@ -1554,7 +1554,7 @@ static av_always_inline void mpeg_motion_lowres(MpegEncContext *s,
             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)){
+            if(!ENABLE_GRAY || !(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);
@@ -1581,7 +1581,7 @@ static av_always_inline void mpeg_motion_lowres(MpegEncContext *s,
     sy <<= 2 - lowres;
     pix_op[lowres-1](dest_y, ptr_y, linesize, h, sx, sy);
 
-    if(!(s->flags&CODEC_FLAG_GRAY)){
+    if(!ENABLE_GRAY || !(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);
@@ -1687,7 +1687,7 @@ static inline void MPV_motion_lowres(MpegEncContext *s,
                 my += s->mv[dir][i][1];
             }
 
-        if(!(s->flags&CODEC_FLAG_GRAY))
+        if(!ENABLE_GRAY || !(s->flags&CODEC_FLAG_GRAY))
             chroma_4mv_motion_lowres(s, dest_cb, dest_cr, ref_picture, pix_op, mx, my);
         break;
     case MV_TYPE_FIELD:
@@ -1974,7 +1974,7 @@ static av_always_inline void MPV_decode_mb_internal(MpegEncContext *s, DCTELEM b
                 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)){
+                if(!ENABLE_GRAY || !(s->flags&CODEC_FLAG_GRAY)){
                     if (s->chroma_y_shift){
                         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);
@@ -1993,7 +1993,7 @@ static av_always_inline void MPV_decode_mb_internal(MpegEncContext *s, DCTELEM b
                 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(!ENABLE_GRAY || !(s->flags&CODEC_FLAG_GRAY)){
                     if(s->chroma_y_shift){//Chroma420
                         add_dct(s, block[4], 4, dest_cb, uvlinesize);
                         add_dct(s, block[5], 5, dest_cr, uvlinesize);
@@ -2026,7 +2026,7 @@ static av_always_inline void MPV_decode_mb_internal(MpegEncContext *s, DCTELEM b
                 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)){
+                if(!ENABLE_GRAY || !(s->flags&CODEC_FLAG_GRAY)){
                     if(s->chroma_y_shift){
                         put_dct(s, block[4], 4, dest_cb, uvlinesize, s->chroma_qscale);
                         put_dct(s, block[5], 5, dest_cr, uvlinesize, s->chroma_qscale);
@@ -2045,7 +2045,7 @@ static av_always_inline void MPV_decode_mb_internal(MpegEncContext *s, DCTELEM b
                 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(!ENABLE_GRAY || !(s->flags&CODEC_FLAG_GRAY)){
                     if(s->chroma_y_shift){
                         s->dsp.idct_put(dest_cb, uvlinesize, block[4]);
                         s->dsp.idct_put(dest_cr, uvlinesize, block[5]);
diff --git a/libavcodec/mpegvideo_common.h b/libavcodec/mpegvideo_common.h
index a5f41bc43ca604df71ee23556a1316f12581615d..0698e1ddfbef690216dd6afa1fc3f82a60a4b9cc 100644
--- a/libavcodec/mpegvideo_common.h
+++ b/libavcodec/mpegvideo_common.h
@@ -104,7 +104,7 @@ static inline void gmc1_motion(MpegEncContext *s,
         }
     }
 
-    if(s->flags&CODEC_FLAG_GRAY) return;
+    if(ENABLE_GRAY && s->flags&CODEC_FLAG_GRAY) return;
 
     motion_x= s->sprite_offset[1][0];
     motion_y= s->sprite_offset[1][1];
@@ -173,7 +173,7 @@ static inline void gmc_motion(MpegEncContext *s,
            a+1, (1<<(2*a+1)) - s->no_rounding,
            s->h_edge_pos, s->v_edge_pos);
 
-    if(s->flags&CODEC_FLAG_GRAY) return;
+    if(ENABLE_GRAY && s->flags&CODEC_FLAG_GRAY) return;
 
     ox= s->sprite_offset[1][0] + s->sprite_delta[0][0]*s->mb_x*8 + s->sprite_delta[0][1]*s->mb_y*8;
     oy= s->sprite_offset[1][1] + s->sprite_delta[1][0]*s->mb_x*8 + s->sprite_delta[1][1]*s->mb_y*8;
@@ -318,7 +318,7 @@ if(s->quarter_sample)
             ff_emulated_edge_mc(s->edge_emu_buffer, ptr_y, s->linesize, 17, 17+field_based,
                              src_x, src_y<<field_based, s->h_edge_pos, s->v_edge_pos);
             ptr_y = s->edge_emu_buffer;
-            if(!(s->flags&CODEC_FLAG_GRAY)){
+            if(!ENABLE_GRAY || !(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, s->h_edge_pos>>1, s->v_edge_pos>>1);
@@ -343,7 +343,7 @@ if(s->quarter_sample)
 
     pix_op[0][dxy](dest_y, ptr_y, linesize, h);
 
-    if(!(s->flags&CODEC_FLAG_GRAY)){
+    if(!ENABLE_GRAY || !(s->flags&CODEC_FLAG_GRAY)){
         pix_op[s->chroma_x_shift][uvdxy](dest_cb, ptr_cb, uvlinesize, h >> s->chroma_y_shift);
         pix_op[s->chroma_x_shift][uvdxy](dest_cr, ptr_cr, uvlinesize, h >> s->chroma_y_shift);
     }
@@ -485,7 +485,7 @@ static inline void qpel_motion(MpegEncContext *s,
         ff_emulated_edge_mc(s->edge_emu_buffer, ptr_y, s->linesize, 17, 17+field_based,
                          src_x, src_y<<field_based, s->h_edge_pos, s->v_edge_pos);
         ptr_y= s->edge_emu_buffer;
-        if(!(s->flags&CODEC_FLAG_GRAY)){
+        if(!ENABLE_GRAY || !(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, s->h_edge_pos>>1, s->v_edge_pos>>1);
@@ -515,7 +515,7 @@ static inline void qpel_motion(MpegEncContext *s,
         qpix_op[1][dxy](dest_y  , ptr_y  , linesize);
         qpix_op[1][dxy](dest_y+8, ptr_y+8, linesize);
     }
-    if(!(s->flags&CODEC_FLAG_GRAY)){
+    if(!ENABLE_GRAY || !(s->flags&CODEC_FLAG_GRAY)){
         pix_op[1][uvdxy](dest_cr, ptr_cr, uvlinesize, h >> 1);
         pix_op[1][uvdxy](dest_cb, ptr_cb, uvlinesize, h >> 1);
     }
@@ -663,7 +663,7 @@ static inline void MPV_motion(MpegEncContext *s,
             mx += mv[0][0];
             my += mv[0][1];
         }
-        if(!(s->flags&CODEC_FLAG_GRAY))
+        if(!ENABLE_GRAY || !(s->flags&CODEC_FLAG_GRAY))
             chroma_4mv_motion(s, dest_cb, dest_cr, ref_picture, pix_op[1], mx, my);
 
         return;
@@ -745,7 +745,7 @@ static inline void MPV_motion(MpegEncContext *s,
             }
         }
 
-        if(!(s->flags&CODEC_FLAG_GRAY))
+        if(!ENABLE_GRAY || !(s->flags&CODEC_FLAG_GRAY))
             chroma_4mv_motion(s, dest_cb, dest_cr, ref_picture, pix_op[1], mx, my);
         break;
     case MV_TYPE_FIELD: