JAZZ Jackie and Roy: ''High Standards.'' Jackie Cain, vocals; Roy Kral, piano, vocals; Paul Johnson, vibes; Dean Johnson, bass; Jeff Brillinger, drums. (Concord Jazz CJ-186.) It's nice to have a new Jackie and Roy album with an old twist. For a while they seemed to be drifting in a kind of wordless Sergio Mendes direction, and it's a joy to hear the good old ''standards'' again, in both senses of the word. After all, reworkings of the best pop and jazz standard songs were their trademark for many years, and old fans will never forget their classic arrangements of tunes like ''Mountain Greenery'' and ''Thou Swell.'' Jackie and Roy sing together with precision and zeal, and with the uncanny communication that their many years of experience together has solidified. Once again their tight, crisp, and swinging renditions of songs like Gershwin's ''Bidin' My Time,'' ''I've Got Rhythm,'' and ''Mine''; Johnny Mercer and Richard Whiting's ''Too Marvelous for Words''; and Hoagy Carmichael's ''Stardust'' grace the listener's ear. Add a spirited jazz tune - Clifford Brown's ''Joy Spring'' - and a lovely movie theme - ''I Watch You Sleep,'' from ''Yanks'' - and the result is a most satisfying recording.