Job fails if number of audio streams in input does not match a known channel layout

[grusell]

Describe the bug
Running a job where the input has 32 mono audio streams, the job fails with a message Could not determine channel layout for audio input.
Partial workaround is to define a defaultChannelLayout for 32 channels, but since no channel layout has 32 channels this will only allow me to use the first 24 channels.

Expected behavior
I would expect this to map to something like an 'UNKNOWN_32_CHANNELS' channel layout, which would allow me to create audioMixPresets using any of the 32 channels.