first gen fire tv stick audio caveats?
my dad has an older sharp tv with two hdmi inputs. hdmi1 is a directv receiver. hdmi2 is a Samsung Blu-ray player. the TV's speakers are disabled, and the TV passes audio from these two sources over an optical cable to a Panasonic soundbar/HTIB/subwoofer thing. i'd include model numbers, but this setup has worked flawlessly for years without any particularly refined configuration in any of the devices' menus.
today I unplugged the Blu-ray player from hdmi2, and plugged in my old first-gen amazon fire tv stick. video works fine, but no audio from the HTIB's speakers. if I plug the Blu-ray player back in to hdmi2, audio from the Blu-ray player is output as expected. plug the fire tv stick back in, no audio is output. same behavior on hdmi1, for the sake of thoroughness. all devices other than fire tv stick work as expected on both hdmi ports, fire tv stick does not work on either port.
if I switch the TV to use its own speakers instead of outputting to the HTIB, the TV speakers do output audio from the fire TV stick.
the HTIB also has its own HDMI input and output. I have never used them before, because for simplicity's sake I don't want my aging dad to have to change inputs on the HTIB in addition to changing inputs on the tv. but for testing purposes, today I connected the fire tv stick to the HTIB's hdmi-in, and ran a cable from the HTIB's hdmi-out to the tv. and switched the HTIB's audio input selector to that hdmi source. the fire tv stick's audio was output as expected.
-audio from the directv box and Blu-ray player connected to the TV's hdmi1 or 2 is successfully sent across the optical connection to the HTIB. (ie, the setup is capable of getting TV hdmi audio output through the HTIB's speakers)
-audio from the fire tv stick connected to the tv's hdmi1 or 2 is successfully output through the TVs own speakers. (ie, the tv knows how to interpret the audio signal from the fire tv stick)
-audio from the fire tv stick connected to the HTIB's hdmi-in is successfully output through the HTIB's speakers (ie, the HTIB knows how to interpret the audio signal from the fire tv stick)
-audio from the fire tv stick connected to the tv's hdmi 1 or 2 fails to make its way across the optical cable and out of the HTIB's speakers.
none of the behavior changes if I modify any of the fire tv stick's available audio settings. which are something like "automatic dolby digital, dolby digital on, dolby digital off." it was set to "dolby digital off" when i started.
is there something special (documented) about the fire tv stick's audio that would cause this setup, which "just works" for the directv box and blu-ray player, to not work for the fire tv stick?