My question is regarding this passage from C. M. von Weber's Clarinet Concerto No. 1. The passage is taken from the exposition of the first movement and has so far been established in F minor.
Bars 20 - 25 seems to be a modulation and transition to the next section in Db Major (starting at Bar 26). Bars 24 - 25 are in the dominant of the new key of Db major (Abdom7), and Bars 26 - 27 are in the tonic of Db major.
Now for the harmonic analysis:
Bar 20: i - V7 - i ( fmin - cdom7 - fmin )
Bar 21: V7 - i - [V7] ( Cdom7 - fmin - Fdom7 )
Bar 22: ? - ? - ? ( Bbmaj - Dbdom7 - fmin)
Bar 23: ? - ? - ? ( bdim7 - Cdom7 - Fmaj)
Bar 24: Db major: V7 - V7 ( Abdom7 - Abdom7 )
So my question is what is happening with the chords in bars 22 - 23 before the Fmaj (6/3) at the end of Bar 23 leads to Abdom7 (7/5/3) by the lower and upper parts falling and rising by a semitone, respectively.
The first violins and cellos are playing in contrary motion by scale, so was it a case of harmonizing between these parts or can these chords be given a harmonic function by way of roman numerals. Are these chords just chromatic ones chosen for their bass notes and such to fit the scale? Or were they chosen with a chord progression in mind?