c->height = mlt_properties_get_int( properties, "height" );
c->time_base.num = mlt_properties_get_int( properties, "frame_rate_den" );
c->time_base.den = mlt_properties_get_int( properties, "frame_rate_num" );
- st->time_base = c->time_base;
+ if ( st->time_base.den == 0 )
+ st->time_base = c->time_base;
c->pix_fmt = pix_fmt ? avcodec_get_pix_fmt( pix_fmt ) : PIX_FMT_YUV420P;
if ( mlt_properties_get( properties, "aspect" ) )