This summary is not the rule. The rule text controls.
If someone tries to use a deposition (sworn testimony taken before trial) as evidence in court, the other side can object to it. The rule for deciding whether that objection is valid is simple: if the same objection would work against the witness if they were sitting in the courtroom testifying live, then it also works against using their deposition instead.
In other words, a deposition doesn't get special treatment just because it was written down earlier. The same rules about what counts as good evidence still apply. If certain testimony would be blocked from a live witness on the stand, like hearsay, irrelevant statements, or something else the rules of evidence don't allow, then that same testimony can be blocked when it shows up in a deposition too.
There are two exceptions built into this rule. It doesn't apply in situations covered by Louisiana Revised Statute 13:3823 or Article 1455, which deal with specific special circumstances. Outside of those exceptions, though, the standard is consistent: courts treat deposition testimony the same way they'd treat someone testifying in person.