mpegvideo: Fix undefined negative shifts in mpeg_motion_internal

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

libavcodec/mpegvideo_motion.c

@@ -321,7 +321,7 @@ void mpeg_motion_internal(MpegEncContext *s,
         s->vdsp.emulated_edge_mc(s->sc.edge_emu_buffer, ptr_y,
                                  s->linesize, s->linesize,
                                  17, 17 + field_based,
-                                 src_x, src_y << field_based,
+                                 src_x, src_y * (1 << field_based),
                                  s->h_edge_pos, s->v_edge_pos);
         ptr_y = s->sc.edge_emu_buffer;
         if (!CONFIG_GRAY || !(s->avctx->flags & AV_CODEC_FLAG_GRAY)) {
@@ -329,12 +329,12 @@ void mpeg_motion_internal(MpegEncContext *s,
             s->vdsp.emulated_edge_mc(uvbuf, ptr_cb,
                                      s->uvlinesize, s->uvlinesize,
                                      9, 9 + field_based,
-                                     uvsrc_x, uvsrc_y << field_based,
+                                     uvsrc_x, uvsrc_y * (1 << field_based),
                                      s->h_edge_pos >> 1, s->v_edge_pos >> 1);
             s->vdsp.emulated_edge_mc(uvbuf + 16, ptr_cr,
                                      s->uvlinesize, s->uvlinesize,
                                      9, 9 + field_based,
-                                     uvsrc_x, uvsrc_y << field_based,
+                                     uvsrc_x, uvsrc_y * (1 << field_based),
                                      s->h_edge_pos >> 1, s->v_edge_pos >> 1);
             ptr_cb = uvbuf;
             ptr_cr = uvbuf + 16;
@@ -542,7 +542,7 @@ static inline void qpel_motion(MpegEncContext *s,
         s->vdsp.emulated_edge_mc(s->sc.edge_emu_buffer, ptr_y,
                                  s->linesize, s->linesize,
                                  17, 17 + field_based,
-                                 src_x, src_y << field_based,
+                                 src_x, src_y * (1 << field_based),
                                  s->h_edge_pos, s->v_edge_pos);
         ptr_y = s->sc.edge_emu_buffer;
         if (!CONFIG_GRAY || !(s->avctx->flags & AV_CODEC_FLAG_GRAY)) {
@@ -550,12 +550,12 @@ static inline void qpel_motion(MpegEncContext *s,
             s->vdsp.emulated_edge_mc(uvbuf, ptr_cb,
                                      s->uvlinesize, s->uvlinesize,
                                      9, 9 + field_based,
-                                     uvsrc_x, uvsrc_y << field_based,
+                                     uvsrc_x, uvsrc_y * (1 << field_based),
                                      s->h_edge_pos >> 1, s->v_edge_pos >> 1);
             s->vdsp.emulated_edge_mc(uvbuf + 16, ptr_cr,
                                      s->uvlinesize, s->uvlinesize,
                                      9, 9 + field_based,
-                                     uvsrc_x, uvsrc_y << field_based,
+                                     uvsrc_x, uvsrc_y * (1 << field_based),
                                      s->h_edge_pos >> 1, s->v_edge_pos >> 1);
             ptr_cb = uvbuf;
             ptr_cr = uvbuf + 16;