mov: Preserve the metadata even when bit-exactness is requested

Make sure to not write the custom `encoder` string in that case.

Bug-Id: 845
CC: libav-stable@libav.org

libavformat/movenc.c

@@ -1768,7 +1768,7 @@ static int mov_write_track_udta_tag(AVIOContext *pb, MOVMuxContext *mov,
     int ret, size;
     uint8_t *buf;
 
-    if (!st || mov->fc->flags & AVFMT_FLAG_BITEXACT)
+    if (!st)
         return 0;
 
     ret = avio_open_dyn_buf(&pb_buf);
@@ -2062,8 +2062,10 @@ static int mov_write_ilst_tag(AVIOContext *pb, MOVMuxContext *mov,
     mov_write_string_metadata(s, pb, "\251wrt", "composer" , 1);
     mov_write_string_metadata(s, pb, "\251alb", "album"    , 1);
     mov_write_string_metadata(s, pb, "\251day", "date"     , 1);
-    if (!mov_write_string_metadata(s, pb, "\251too", "encoding_tool", 1))
+    if (!mov_write_string_metadata(s, pb, "\251too", "encoding_tool", 1)) {
+        if (!(s->flags & AVFMT_FLAG_BITEXACT))
             mov_write_string_tag(pb, "\251too", LIBAVFORMAT_IDENT, 0, 1);
+    }
     mov_write_string_metadata(s, pb, "\251cmt", "comment"  , 1);
     mov_write_string_metadata(s, pb, "\251gen", "genre"    , 1);
     mov_write_string_metadata(s, pb, "\251cpy", "copyright", 1);
@@ -2166,9 +2168,6 @@ static int mov_write_udta_tag(AVIOContext *pb, MOVMuxContext *mov,
     int ret, size;
     uint8_t *buf;
 
-    if (s->flags & AVFMT_FLAG_BITEXACT)
-        return 0;
-
     ret = avio_open_dyn_buf(&pb_buf);
     if (ret < 0)
         return ret;
@@ -2188,6 +2187,7 @@ static int mov_write_udta_tag(AVIOContext *pb, MOVMuxContext *mov,
         mov_write_string_metadata(s, pb_buf, "\251aut", "author",      0);
         mov_write_string_metadata(s, pb_buf, "\251alb", "album",       0);
         mov_write_string_metadata(s, pb_buf, "\251day", "date",        0);
+        if (!(s->flags & AVFMT_FLAG_BITEXACT))
             mov_write_string_metadata(s, pb_buf, "\251swr", "encoder", 0);
         mov_write_string_metadata(s, pb_buf, "\251des", "comment",     0);
         mov_write_string_metadata(s, pb_buf, "\251gen", "genre",       0);

tests/ref/vsynth/vsynth1-mpeg4

-dc927acd770e19a97456ecbd4d786938 *tests/data/fate/vsynth1-mpeg4.mp4
-540180 tests/data/fate/vsynth1-mpeg4.mp4
+173f524d5cd2591709bf1d5d2818b420 *tests/data/fate/vsynth1-mpeg4.mp4
+540241 tests/data/fate/vsynth1-mpeg4.mp4
 8828a375448dc5c2215163ba70656f89 *tests/data/fate/vsynth1-mpeg4.out.rawvideo
 stddev:    7.97 PSNR: 30.10 MAXDIFF:  105 bytes:  7603200/  7603200

tests/ref/vsynth/vsynth2-mpeg4

-f60260ca447624a19ad8307abad7a431 *tests/data/fate/vsynth2-mpeg4.mp4
-159432 tests/data/fate/vsynth2-mpeg4.mp4
+5476cf4dc144eac67b12737fd8966641 *tests/data/fate/vsynth2-mpeg4.mp4
+159493 tests/data/fate/vsynth2-mpeg4.mp4
 871fda3853f4766669ad875923920bd5 *tests/data/fate/vsynth2-mpeg4.out.rawvideo
 stddev:    6.02 PSNR: 32.53 MAXDIFF:   89 bytes:  7603200/  7603200