Mixed metres (Alternating time signatures)

Your idea

I propose to implement alternating time signatures in MuseScore Studio, which would mean a fixed pattern of alternating metres.

In contrast to the interchanging of a simple- /compound-time metre (see #25092), with a mixed metre, bars of different durations alternate.

It is more common to treat the pattern of alternating time signatures as single bars, but it is also allowed to use a dotted bar-line. The user should be able to configure this (however, by default it is recommended to still use the usual solid bar-line).

The user should also be able to specify a dual time signature with a "-" sign between each, which means an irregular alternation of the metres (however, this is more relevant to #25092).

There are also so-called aggregate time signatures (metres of mixed denominators) in notation. Unlike the previous "dual" time signatures, with aggregate time signatures, the bar is not divided into several, and if it is divided (where it may be useful), then only by a dotted bar-line:

Problem to be solved

The use of alternating time signatures is useful in chamber music to save writing in many alternating Time signatures.
Mixed meters are also often frequently used in styles such as progressive rock, jazz, and world music. I'll give you an example on the track Father John Misty - "Only Son of the Ladies man". The verses on this one last ten beats long, but using 10/4 is quite awkward. Again, you have apparent downbeats within the bar, so using 4/4 + 2/4 + 4/4 is probably better. Another option could be alternating between 6/4 and 4/4 — that way, it might be easier to count the verses as two-measure phrases instead of three[^*].

[^*]: Source: «Alternating Time Signatures, or One Big Meter?»

Prior art

There are different types of time signatures in Dorico which can indicate to various and complex metres:

Dorco also automatically enters dashed bar-lines to show the divisions between each metre.

Additional context

Alternating time signatures were discussed on the forum 14 years ago (see Alternating time signatures). This topic was also discussed here.

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