tiffdec: support predictor type 2 with RGB48 pixel format

libavcodec/tiff.c

@@ -635,12 +635,26 @@ static int decode_frame(AVCodecContext *avctx,
         dst   = p->data[0];
         soff  = s->bpp >> 3;
         ssize = s->width * soff;
+        if (s->avctx->pix_fmt == PIX_FMT_RGB48LE) {
+            for (i = 0; i < s->height; i++) {
+                for (j = soff; j < ssize; j += 2)
+                    AV_WL16(dst + j, AV_RL16(dst + j) + AV_RL16(dst + j - soff));
+                dst += stride;
+            }
+        } else if (s->avctx->pix_fmt == PIX_FMT_RGB48BE) {
+            for (i = 0; i < s->height; i++) {
+                for (j = soff; j < ssize; j += 2)
+                    AV_WB16(dst + j, AV_RB16(dst + j) + AV_RB16(dst + j - soff));
+                dst += stride;
+            }
+        } else {
             for (i = 0; i < s->height; i++) {
                 for (j = soff; j < ssize; j++)
                     dst[j] += dst[j - soff];
                 dst += stride;
             }
         }
+    }
 
     if (s->photometric == TIFF_PHOTOMETRIC_WHITE_IS_ZERO) {
         dst = p->data[0];