CarPlay marks guidance audio apart from media, but the sink always built
its AudioTrack from usage/content-type attributes. On head units that
expose navigation on a dedicated mixer output, guidance shares the media
channels, so the next turn is announced over the music in every seat.
BYD puts navigation on stream type 14, the driver-side speaker.
Add an "Audio routing" section with a 0-20 stream type grid and a test
tone, persist the selection, and build the AudioTrack on that stream
type. When the ROM rejects the stream type the track is rebuilt from
usage attributes, so devices without such an output keep today's
behavior (the diagnostic log reports route=usage or
route=streamType=N(fallback=usage)).
The advanced audio channel mapping switch is now visible on the mobile
flavor too, still off by default, so usage/content-type routing can be
picked at runtime instead of by editing resources, and the automotive
map routes default and compatibility to the navigation bus rather than
sharing media.
baileileicn
e85285e03d