Can a defendant's confrontation right be violated by admitting the testimony of an unavailable witness at a preliminary hearing?

confrontation is not absolute. [Citations.] 'Traditionally, there has been "an exception to the confrontation requirement where a witness is unavailable and has given testimony at previous judicial proceedings against the same defendant [and] which was subject to cross-examination . . . ." [Citation.]' [Citation.] Pursuant to this exception, the preliminary hearing testimony of an unavailable witness may be admitted at trial without violating a defendant's confrontation right. [Citation.]" (People v. Herrera (2010) 49 Cal.4th 613, 621.) When the requirements of Evidence Code section 1291 are met, a defendant's constitutional right of confrontation is not violated by the admission of former testimony. (Herrera, at p. 621.)