Dobly truehd tracks with 7.1 channels muxed in mkv are displayed as "7.1".
Dobly e-ac3 tracks with 7.1 channels muxed in mkv are displayed as "8 channels" instead.
See attached picture:
This is not an issue of matroska, as it only stores a single number for the total number of channels (2, 6, 8, etc) and not the layout.
The layout information is something that lav filters find, probably by bitstream parsing or something. But whatever they do, it's not done for the eac-3 tracks.
This is purely a cosmetic issue, but would be nice if it could be fixed. Thanks.