diff --git a/libavcodec/mjpegenc.c b/libavcodec/mjpegenc.c
index 381f0fb626..b476bcd232 100644
--- a/libavcodec/mjpegenc.c
+++ b/libavcodec/mjpegenc.c
@@ -137,7 +137,7 @@ static void jpeg_table_header(MpegEncContext *s)
     if(s->avctx->active_thread_type & FF_THREAD_SLICE){
         put_marker(p, DRI);
         put_bits(p, 16, 4);
-        put_bits(p, 16, s->mb_width);
+        put_bits(p, 16, s->mb_width*2/s->mjpeg_hsample[0]);
     }
 
     /* huffman table */
@@ -458,23 +458,31 @@ static void encode_block(MpegEncContext *s, DCTELEM *block, int n)
 void ff_mjpeg_encode_mb(MpegEncContext *s, DCTELEM block[6][64])
 {
     int i;
-    for(i=0;i<5;i++) {
-        encode_block(s, block[i], i);
-    }
-    if (s->chroma_format == CHROMA_420) {
-        encode_block(s, block[5], 5);
-    } else if (s->chroma_format == CHROMA_422) {
-        encode_block(s, block[6], 6);
+    if (s->chroma_format == CHROMA_444) {
+        encode_block(s, block[0], 0);
+        encode_block(s, block[2], 2);
+        encode_block(s, block[4], 4);
+        encode_block(s, block[8], 8);
         encode_block(s, block[5], 5);
-        encode_block(s, block[7], 7);
-    } else {
+        encode_block(s, block[9], 9);
+
+        encode_block(s, block[1], 1);
+        encode_block(s, block[3], 3);
         encode_block(s, block[6], 6);
-        encode_block(s, block[8], 8);
         encode_block(s, block[10], 10);
-        encode_block(s, block[5], 5);
         encode_block(s, block[7], 7);
-        encode_block(s, block[9], 9);
         encode_block(s, block[11], 11);
+    } else {
+        for(i=0;i<5;i++) {
+            encode_block(s, block[i], i);
+        }
+        if (s->chroma_format == CHROMA_420) {
+            encode_block(s, block[5], 5);
+        } else {
+            encode_block(s, block[6], 6);
+            encode_block(s, block[5], 5);
+            encode_block(s, block[7], 7);
+        }
     }
 
     s->i_tex_bits += get_bits_diff(s);
diff --git a/libavcodec/mpegvideo_enc.c b/libavcodec/mpegvideo_enc.c
index 08dcf9e793..aff12c6f8e 100644
--- a/libavcodec/mpegvideo_enc.c
+++ b/libavcodec/mpegvideo_enc.c
@@ -751,6 +751,9 @@ av_cold int ff_MPV_encode_init(AVCodecContext *avctx)
             s->mjpeg_vsample[0] = s->mjpeg_hsample[0] =
             s->mjpeg_vsample[1] = s->mjpeg_hsample[1] =
             s->mjpeg_vsample[2] = s->mjpeg_hsample[2] = 1;
+        } else if (avctx->pix_fmt == AV_PIX_FMT_YUV444P || avctx->pix_fmt == AV_PIX_FMT_YUVJ444P) {
+            s->mjpeg_vsample[0] = s->mjpeg_vsample[1] = s->mjpeg_vsample[2] = 2;
+            s->mjpeg_hsample[0] = s->mjpeg_hsample[1] = s->mjpeg_hsample[2] = 1;
         } else {
             s->mjpeg_vsample[0] = 2;
             s->mjpeg_vsample[1] = 2 >> chroma_v_shift;
diff --git a/tests/ref/vsynth/vsynth1-mjpeg-444 b/tests/ref/vsynth/vsynth1-mjpeg-444
index 3ad0c51195..ba2491491a 100644
--- a/tests/ref/vsynth/vsynth1-mjpeg-444
+++ b/tests/ref/vsynth/vsynth1-mjpeg-444
@@ -1,4 +1,4 @@
-bf3e8f03857c8b3c7b1cdc7bb1aa5bae *tests/data/fate/vsynth1-mjpeg-444.avi
-1987582 tests/data/fate/vsynth1-mjpeg-444.avi
+94ca37e075ee24047b5dcd8f27b51a9f *tests/data/fate/vsynth1-mjpeg-444.avi
+1989780 tests/data/fate/vsynth1-mjpeg-444.avi
 313a4a76af13d5879ea4910107b7ea74 *tests/data/fate/vsynth1-mjpeg-444.out.rawvideo
 stddev:    7.37 PSNR: 30.77 MAXDIFF:   63 bytes:  7603200/  7603200
diff --git a/tests/ref/vsynth/vsynth2-mjpeg-444 b/tests/ref/vsynth/vsynth2-mjpeg-444
index e04c31c7d7..b09f889ca0 100644
--- a/tests/ref/vsynth/vsynth2-mjpeg-444
+++ b/tests/ref/vsynth/vsynth2-mjpeg-444
@@ -1,4 +1,4 @@
-0af500d33a7e4d04e9778fb9ed6180b3 *tests/data/fate/vsynth2-mjpeg-444.avi
-856628 tests/data/fate/vsynth2-mjpeg-444.avi
+10abd087833f9bdf3b77c1aa37dc11e5 *tests/data/fate/vsynth2-mjpeg-444.avi
+851442 tests/data/fate/vsynth2-mjpeg-444.avi
 34edcb9c87ff7aac456a4fb07f43504b *tests/data/fate/vsynth2-mjpeg-444.out.rawvideo
 stddev:    4.05 PSNR: 35.96 MAXDIFF:   49 bytes:  7603200/  7603200