avformat/mxfdec: support subsecond precision of decoded timestamps

Signed-off-by: Marton Balint <cus@passwd.hu>

libavformat/mxfdec.c

@@ -2556,12 +2556,14 @@ fail_and_free:
 static int64_t mxf_timestamp_to_int64(uint64_t timestamp)
 {
     struct tm time = { 0 };
+    int msecs;
     time.tm_year = (timestamp >> 48) - 1900;
     time.tm_mon  = (timestamp >> 40 & 0xFF) - 1;
     time.tm_mday = (timestamp >> 32 & 0xFF);
     time.tm_hour = (timestamp >> 24 & 0xFF);
     time.tm_min  = (timestamp >> 16 & 0xFF);
     time.tm_sec  = (timestamp >> 8  & 0xFF);
+    msecs        = (timestamp & 0xFF) * 4;
 
     /* Clip values for legacy reasons. Maybe we should return error instead? */
     time.tm_mon  = av_clip(time.tm_mon,  0, 11);
@@ -2569,8 +2571,9 @@ static int64_t mxf_timestamp_to_int64(uint64_t timestamp)
     time.tm_hour = av_clip(time.tm_hour, 0, 23);
     time.tm_min  = av_clip(time.tm_min,  0, 59);
     time.tm_sec  = av_clip(time.tm_sec,  0, 59);
+    msecs        = av_clip(msecs, 0, 999);
 
-    return (int64_t)av_timegm(&time) * 1000000;
+    return (int64_t)av_timegm(&time) * 1000000 + msecs * 1000;
 }
 
 #define SET_STR_METADATA(pb, name, str) do { \