diff --git a/libswscale/x86/scale.asm b/libswscale/x86/scale.asm
index a3cb0b1bd6..6282ab2c69 100644
--- a/libswscale/x86/scale.asm
+++ b/libswscale/x86/scale.asm
@@ -408,12 +408,14 @@ SCALE_FUNC %1, %2, X, X8, 7, %3
 SCALE_FUNCS  8, 15, %1
 SCALE_FUNCS  9, 15, %2
 SCALE_FUNCS 10, 15, %2
+SCALE_FUNCS 12, 15, %2
 SCALE_FUNCS 14, 15, %2
 SCALE_FUNCS 16, 15, %3
 %endif ; !sse4
 SCALE_FUNCS  8, 19, %1
 SCALE_FUNCS  9, 19, %2
 SCALE_FUNCS 10, 19, %2
+SCALE_FUNCS 12, 19, %2
 SCALE_FUNCS 14, 19, %2
 SCALE_FUNCS 16, 19, %3
 %endmacro
diff --git a/libswscale/x86/swscale_mmx.c b/libswscale/x86/swscale_mmx.c
index bb88d3478a..5dd928ada3 100644
--- a/libswscale/x86/swscale_mmx.c
+++ b/libswscale/x86/swscale_mmx.c
@@ -273,11 +273,13 @@ extern void ff_hscale ## from_bpc ## to ## to_bpc ## _ ## filter_n ## _ ## opt(
     SCALE_FUNC(filter_n,  8, 15, opt); \
     SCALE_FUNC(filter_n,  9, 15, opt); \
     SCALE_FUNC(filter_n, 10, 15, opt); \
+    SCALE_FUNC(filter_n, 12, 15, opt); \
     SCALE_FUNC(filter_n, 14, 15, opt); \
     SCALE_FUNC(filter_n, 16, 15, opt); \
     SCALE_FUNC(filter_n,  8, 19, opt); \
     SCALE_FUNC(filter_n,  9, 19, opt); \
     SCALE_FUNC(filter_n, 10, 19, opt); \
+    SCALE_FUNC(filter_n, 12, 19, opt); \
     SCALE_FUNC(filter_n, 14, 19, opt); \
     SCALE_FUNC(filter_n, 16, 19, opt)
 
@@ -387,6 +389,9 @@ void ff_sws_init_swScale_mmx(SwsContext *c)
     } else if (c->srcBpc == 10) { \
         hscalefn = c->dstBpc <= 14 ? ff_hscale10to15_ ## filtersize ## _ ## opt2 : \
                                      ff_hscale10to19_ ## filtersize ## _ ## opt1; \
+    } else if (c->srcBpc == 12) { \
+        hscalefn = c->dstBpc <= 14 ? ff_hscale12to15_ ## filtersize ## _ ## opt2 : \
+                                     ff_hscale12to19_ ## filtersize ## _ ## opt1; \
     } else if (c->srcBpc == 14 || ((c->srcFormat==PIX_FMT_PAL8||isAnyRGB(c->srcFormat)) && av_pix_fmt_descriptors[c->srcFormat].comp[0].depth_minus1<15)) { \
         hscalefn = c->dstBpc <= 14 ? ff_hscale14to15_ ## filtersize ## _ ## opt2 : \
                                      ff_hscale14to19_ ## filtersize ## _ ## opt1; \
diff --git a/tests/ref/lavfi/pixfmts_scale b/tests/ref/lavfi/pixfmts_scale
index 6b79d5e608..9c4bd3a2ac 100644
--- a/tests/ref/lavfi/pixfmts_scale
+++ b/tests/ref/lavfi/pixfmts_scale
@@ -42,8 +42,8 @@ yuv411p             1143e7c5cc28fe0922b051b17733bc4c
 yuv420p             fdad2d8df8985e3d17e73c71f713cb14
 yuv420p10be         418039dbd82cf612db88417276aa0d1a
 yuv420p10le         ff7e5321208ab995b4f95634ebdf192b
-yuv420p12be         816c566952179b9723d68b5031882c09
-yuv420p12le         7bc483edbca22ae9e4e09395adc7a4ca
+yuv420p12be         a6e9e4ee831b1d7ee1c3e9bf7bbeac13
+yuv420p12le         d431d31edd2011fc80d2f7e1894dddb6
 yuv420p14be         d00e95efb73c5598c73922c909193dbf
 yuv420p14le         9cd18a56ff50aa4fde7294d2f67ec4fa
 yuv420p16be         31988e9a5d6acacaa710f67bc1172f3a
@@ -53,8 +53,8 @@ yuv420p9le          c136dce5913a722eee44ab72cff664b2
 yuv422p             918e37701ee7377d16a8a6c119c56a40
 yuv422p10be         315654908d50718e175aae018c484732
 yuv422p10le         91bbc78a9a56f659b55abc17722dcc09
-yuv422p12be         3c50e9a3365da86e8b0645210d3679cc
-yuv422p12le         762051def8a4b3994b91099722fab749
+yuv422p12be         e2cf9c7e500f0badffe38cfef4bae7e1
+yuv422p12le         7f79c4ca498a12cac5d548a976e5136c
 yuv422p14be         09d11457639e808f0db8428aabcdf97a
 yuv422p14le         041a8f46e026eb4d01770a5fa2f8fd28
 yuv422p16be         e7e34fe9264784763ab6cb406524c0f3
@@ -65,8 +65,8 @@ yuv440p             461503fdb9b90451020aa3b25ddf041c
 yuv444p             81b2eba962d12e8d64f003ac56f6faf2
 yuv444p10be         fb304d77c6d2e18df5938662a22176f0
 yuv444p10le         b17136913eb066dca6be6af645b9f7e8
-yuv444p12be         55270eda3e388a0cb4d24c07bbf9677d
-yuv444p12le         fb6fca8a8578c482381e19efe8ce7dc8
+yuv444p12be         b720325bf49627ceb35f868eadab1cea
+yuv444p12le         b8020a5ff95de8ecb8d37d851481e80d
 yuv444p14be         b3fb36c759967caf2d83dce3ed5f993d
 yuv444p14le         818c5583fa2e0b9befb3f60d58ece6c3
 yuv444p16be         0da9bed80f5542682ab286f3261cf24c