Tonight's "Andre' Watts in Concert" on Channel 26 at 9 (simulcast on WETA-FM) is both superb music and splendid television.

The central event is a performance of Beethoven's "Emperor" Concerto, that most extroverted and magisterial work, in which Watts is joined by the Indianapolis Symphony Orchestra under John Nelson, the conductor who made such a strong impression in the recent Mostly Mozart concerts at the Kennedy Center.

Just as an interpretation, it is memorable. Watts' remarkable command of the keyboard never sounded more self-confident. He has a capacity to move from the most formidable sonorities to the most delicate trills that even a Pollini would be hard pressed to match. For instance, Watts sails into the first movement cadenza at breakneck speed, but the impression you have when it is over is not of immensity, but of finesse.

The best part, though, comes last. After a tender, tonally voluptuous slow movement, there is that mysterious transition into the last movement, and then the rondo bursts forth in all its blustery force. If Watts' performance of the earlier sections are merely grand, his last movement is truly remarkable. The "Emperor" tends to bring out the most dedicated that is in any pianist. But in this performance Watts gives the last movement an uninhibited swagger that is delectable. He hits that narrow line between Beethoven's hilarity and his dignity just about perfectly.

All this is much aided by camera work of a quality considerably more imaginative than one encounters in the current Boston Symphony and Los Angeles Philharmonic telecasts. One innovation that this viewer cannot recall seeing before is a full view of the keyboard directly from above. The man who apparently gets the credit for this is Thomas L. Merklinger, the executive producer, who is from WFYI-TV in Indianapolis.

Impressive as this is, Merklinger's real triumph comes in the intermission, the usual dead spot of concert broadcasts. He mixes footage of the planning session between Watts and Nelson in Nelson's office (Nelson is playing the solo music on the piano) with sequences from the orchestra rehearsals.

This section is further strengthened by the fact that Nelson and Watts are uncommonly articulate. And Watts, whose career was launched 20 years ago by a televised New York Philharmonic Young People's Concert under Leonard Bernstein, is engagingly photogenic. Not only does he seem to be sweating through the "Emperor," he is.