[FFmpeg-cvslog] avfilter/w3fdif: do not write to line before start line

[Muhammad Faiz]

ffmpeg | branch: master | Muhammad Faiz <mfcc64 at gmail.com> | Sat Jul 22 18:46:07 2017 +0700| [7e9f5500039a31148dc971270ab569015e0ea247] | committer: Muhammad Faiz

avfilter/w3fdif: do not write to line before start line

That line has been written by previous job.
Fix tsan warning.

Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Muhammad Faiz <mfcc64 at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=7e9f5500039a31148dc971270ab569015e0ea247
---

 libavfilter/vf_w3fdif.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavfilter/vf_w3fdif.c b/libavfilter/vf_w3fdif.c
index b7872db341..c6a6550778 100644
--- a/libavfilter/vf_w3fdif.c
+++ b/libavfilter/vf_w3fdif.c
@@ -366,7 +366,7 @@ static int deinterlace_slice(AVFilterContext *ctx, void *arg, int jobnr, int nb_
     int j, y_in, y_out;
 
     /* copy unchanged the lines of the field */
-    y_out = start + (s->field == cur->top_field_first) - (start & 1);
+    y_out = start + ((s->field == cur->top_field_first) ^ (start & 1));
 
     in_line  = cur_data + (y_out * cur_line_stride);
     out_line = dst_data + (y_out * dst_line_stride);
@@ -379,7 +379,7 @@ static int deinterlace_slice(AVFilterContext *ctx, void *arg, int jobnr, int nb_
     }
 
     /* interpolate other lines of the field */
-    y_out = start + (s->field != cur->top_field_first) - (start & 1);
+    y_out = start + ((s->field != cur->top_field_first) ^ (start & 1));
 
     out_line = dst_data + (y_out * dst_line_stride);