What is this quintet from a Swedish movie?

[tuatara442442]

A quite hard to predict answer: a work for four soloists and reduction of the orchestral part

[Theodore S.]

It seems to me like it could be either way. If this was confirmed to be a relatively early Mozart piece from around the time of his Concertone for 2 violins, I wouldn't be surprised at all. There are enough mildly unusual things about the Sinfonia Concertante which could be convincingly-explained by both the Mozart and Not-Mozart camps. (The strangest thing to me is the choice of the keys, in that all the movements are in E-flat major - but Mozart did write multi-movement pieces where all movements are of one key, such as the Piano Sonata no. 11. Besides, his 2-movement Horn Concerti have more unusual structures.) But if it is an unsung composer's work, it's a very close second to Mozart's own music.

[TerraEpon]

Now I remember all the controversy surrounding this work, hence the odd "297b" Köchel number, K.297 being the familiar Mozart Sinfonia Concertante and this being what might be termed the Mostly Mozart Sinfonia Concertante.

No, K 297 is Symphony No. 31,

A myriad of works have a catalog with a letter in them. Most of them are simply later attempts to place them in chronology (for instance, Symphony 31 is also K 300a). If by 'the familiar' one you mean the Violin, Viola and Orchestra one, that's K 364/K 320d.

K 297b is the work as we know it today, however the original, which is lost, is K 297B.

[eschiss1]

What'cha talking about? Mozart K.297 is his Paris symphony.
Btw "K6 300a" is no longer a thing. The new Kochel edition is doing things over again.

[Alan Howe]

So, to sum up: we're talking here about K.297b, whoever it is by (in a chamber arrangement):

https://en.wikipedia.org/wiki/Sinfonia_Concertante_for_Four_Winds  - general info about the orchestral version.

https://imslp.org/wiki/Sinfonia_concertante_in_E-flat_major,_K.297b/Anh.C_14.01_(Mozart,_Wolfgang_Amadeus) - for details of chamber version: click on 'Arrangements and Transcriptions'.

[John Boyer]

No, K 297 is Symphony No. 31,

[...] If by 'the familiar' one you mean the Violin, Viola and Orchestra one, that's K 364/K 320d.

Yes, that's the one I meant.