HAVE YOU bought a DVD lately? Does it have deleted scenes, out-takes, documentaries of any kind, interviews with the main players? There’s a fair chance it does, even if it’s not one of those special editions that’s loaded with add-ons on an extra disc. And the reason is pretty obvious – people love getting on the inside track.

Okay, so some of the extras are essentially commercial packages, promotional material, pure and simple. But sometimes they’re not. Take the interviews that Criterion provided in its set of French director Eric Rohmer’s Moral Tales. These are extraordinarily revealing documents, not readily available elsewhere. The context setting for another Criterion issue, Robert Altman’s Secret Honor, a one-man tour-de-force featuring Philip Baker Hall as Richard Nixon, makes an extraordinary film and performance seem even more exceptional.

In terms of behind-the-scenes revelations, the world of film is streets ahead of classical music, which tends to maintain a very sober front, whether in concert, on disc or on video. There are exceptions, of course, not least when accidents occur. I once heard BBC Radio 3 broadcast a studio recording of a well-known early keyboard specialist playing a particular passage again and again, between discussions with the producer. It wasn’t intended to be that way. Somehow, the necessary editing never got completed. RTÉ Lyric FM broadcast a feature in which the to-ing and fro-ing about minutiae of French pronunciation between producer and presenter got transmitted to the world rather than consigned to the editing floor.

There’s the famous Leonard Bernstein/Glenn Gould contretemps, in which Bernstein made a speech from the stage dissociating himself from the interpretative approach that was going to be adopted by Gould in their performance of Brahms’s First Piano Concerto. The concert took place in 1962, and the performance achieved an “official” release in 1998. In another, more recent conductor/pianist falling-out, Claudio Abbado and Hélène Grimaud cancelled performances they were to give together on the basis of “artistic differences”.

As a student, I did some page-turning for recordings of chamber music and song for RTÉ radio, soaking up the details of the procedures and marvelling at the distinctions between the process and the final product. I particularly cherish a memory of a faulty studio connection, which in those pre-digital days caused the return signal for an echo effect to add nothing musical to the mix, but delivered instead the live commentary from the day’s racing at Leopardstown. What wouldn’t the music-lovers of today give to hear genuine rejected takes from the great and the good of the recording world, the versions that nearly made it into the final edit, and perhaps a discussion of the reasons that they didn’t. The pre-digital, pre-LP era of 78rpm recordings, where the matrix numbers document which take was used, leave fascinating hints.

In those days, recordings were made one four-minute side at a time. If there was a fault, the whole four minutes had to be done again. Rachmaninov set down his Third Symphony with the Philadelphia Orchestra without going beyond a second take, and most of his notoriously difficult Third Concerto was done in single takes (one side went to a second take, one to a third).

But when working with Fritz Kreisler on Grieg’s Third Violin Sonata, each side was done five times, and in the finale of Beethoven’s Sonata in G, Op 30 No 3, they had seven goes at the Finale. And when Rachmaninov recorded his most famous piece, the Prelude in C sharp minor, in 1928, he did it no less than 23 times. What was going on that day? Modern recordings, sadly, don’t even divulge as much as we know about Rachmaninov.

* WHAT GOTme thinking of classical music’s shyness, its concentration on presenting a front of unfazed perfection was the National Chamber Choir’s decision to present a lunchtime open rehearsalat the Mahony Hall of The Helix last Friday. Rehearsals can be revelatory, even ones where the public is allowed to eavesdrop and the performers know that they are effectively on the record. I have cherished memories of watching Stockhausen at work in the Barbican, bringing his spatially acute ear to bear on minute details of balance in his early electronic masterpiece Gesang der Jünglinge(written for five-track tape in the mid-1950s), or hearing Mariss Jansons balance offstage effects in one of his recordings of Respighi with the Oslo Philharmonic Orchestra, or witnessing Michael Tilson Thomas worry over minute details in Mahler’s Eighth Symphony with the San Francisco Symphony.

Rehearsal is, among other things, a process to secure the avoidance of failure. It’s inevitable that failures will crop up. Having the chance to see how they are dealt with, eliminated or forestalled, can be profoundly illuminating.

The NCC’s conductor, Paul Hillier, drew his rehearsal listeners into the action. It was a small enough gathering for him to invite everyone up on to the stage, so that singers and listeners could be as close as possible. He created a relaxed atmosphere, and chatted freely about the background to the pieces he had chosen. But after that, unfortunately, it was more concert than rehearsal. The programme was given in the performing order of the concert, there was no interruption, no revelatory exchange between conductor and singers. But the atmosphere was certainly different, much more relaxed than an actual concert, and the singing was more relaxed too, less projected and often that bit more sheerly beautiful as well.

* The RTÉ NationalSymphony Orchestra had a busy week, giving concerts in Waterford on Thursday (when the main work was Brahms’s First Symphony), in Dublin on Friday (the Brahms replaced by Prokofiev’s Third, with Alan Buribayev glorying in its combination of sophistication and crudeness), and again in Dublin on Sunday afternoon (with Finghin Collins playing finely-sculpted Beethoven with Australian conductor Alexander Briger).

Collins and Briger engaged in a post-concert discussion with the orchestra’s principal clarinettist John Finucane. There was ritual self-congratulation about the wonderful concert, some discussion about pre-performance experiences (Collins all equable, Briger draining of energy before firing up), talk of upcoming engagements, and an audience question about how many works Collins can keep in his head at any time (four or five that he could play tomorrow, 10 or 12 he could have ready in another two weeks). It’s not easy to talk about music, but by the standards of the best, there was very little revelatory in this discussion.

Collins, who has Rachmaninov’s Third Concerto on his wish list to perform, is going to play a new concerto by Deirdre Gribbin next May and hasn’t seen a note of the new piece yet.

What will he do, someone asked, if it’s as hard as the Rachmaninov? “Nobody will know,” he replied, with total honesty and professionalism.