avcodec/mjpegdec: support adob transform 2

Fixes Ticket3426
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/mjpegdec.c

@@ -2092,6 +2092,28 @@ the_end:
             }
         }
     }
+    if (s->adobe_transform == 2 && s->avctx->pix_fmt == AV_PIX_FMT_YUVA444P) {
+        int w = s->picture_ptr->width;
+        int h = s->picture_ptr->height;
+        for (i=0; i<h; i++) {
+            int j;
+            uint8_t *dst[4];
+            for (index=0; index<4; index++) {
+                dst[index] =   s->picture_ptr->data[index]
+                             + s->picture_ptr->linesize[index]*i;
+            }
+            for (j=0; j<w; j++) {
+                int k = dst[3][j];
+                int r = (255 - dst[0][j]) * k;
+                int g = (128 - dst[1][j]) * k;
+                int b = (128 - dst[2][j]) * k;
+                dst[0][j] = r*257 >> 16;
+                dst[1][j] = (g*257 >> 16) + 128;
+                dst[2][j] = (b*257 >> 16) + 128;
+                dst[3][j] = 255;
+            }
+        }
+    }
 
     if (s->stereo3d) {
         AVStereo3D *stereo = av_stereo3d_create_side_data(data);