libavformat/mov.c: Handle timecode from tmcd atom in counter mode

When the timecode value is in counter mode then it is important to use
the timescale and frameduration to calculate the timecode fps.

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

libavformat/mov.c

@@ -1658,6 +1658,13 @@ static int mov_parse_stsd_data(MOVContext *c, AVIOContext *pb,
                 st->codec->flags2 |= CODEC_FLAG2_DROP_FRAME_TIMECODE;
             st->codec->time_base.den = st->codec->extradata[16]; /* number of frame */
             st->codec->time_base.num = 1;
+            /* adjust for per frame dur in counter mode */
+            if (tmcd_ctx->tmcd_flags & 0x0008) {
+                int timescale = AV_RB32(st->codec->extradata + 8);
+                int framedur = AV_RB32(st->codec->extradata + 12);
+                st->codec->time_base.den *= timescale;
+                st->codec->time_base.num *= framedur;
+            }
             if (size > 30) {
                 uint32_t len = AV_RB32(st->codec->extradata + 18); /* name atom length */
                 uint32_t format = AV_RB32(st->codec->extradata + 22);