mpv's ao_audiotrack hardcoded stereo IEC61937 frames, which cannot
carry TrueHD MAT or DTS-HD MA 8-channel bursts, and the app fed
audio-spdif an empty list in self-defense because mpv
force-passthroughs every codec named there with no decode fallback.
The mpv path therefore decoded everything, and passthrough had to be
enabled by hand on every install.
The Kotlin audio route probe (AudioOutputPolicy) now feeds mpv a
per-route audio-spdif list, the fork's multichannel IEC61937 patch
(pinned libmpv v1.1.3) provides the burst geometry, and E-AC3, TrueHD
and DTS-HD MA bitstream on the mpv path. Android TV installs with no
stored preference default to passthrough on, on both backends; an
explicit user choice is preserved.
Verified by route probing and mpv logs on Shield and Box R; no AVR was
in the loop, so receiver-side decode is unconfirmed.
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