Set Audio to Dolby Digital - great relief although would prefer AUTO smarts of ATV3; I suspect that the removal of Toslink(SPDIF) Out impacted the software/firmware to a point where ATV4 lost the smarts to recognize source and seamlessly encode/decode both audio and video.
It is my understanding that the HDMI connection has a greater capacity specification. Others have speculated that the dropping of the optical audio output was to ensure adequate compatibility with the newly added DD+ 7.1 connection requirements. AV output worked fine under TV4 tvOS v9.0 and v9.0.1 until the engineers removed the ability to pass generic DD and DD+ bitstreams through to the downstream device. This is my only major complaint at this time as far as TV4 reduced capabilities are concerned.
Set Audio Loud Noises to On (Loud) - Now I can hear the Cannonball bounce across the prairie in Patriot and U2 belt out In the Name of Love.
The dynamic range issue is actually a separate problem. I always encode my AC-3 content with a full dynamic range (-31 db) setting for my listening and switch to ALC when my wife decides to join me in viewing something. I.e., she prefers a -27 db (common home theater) setting which I pre-programm into my AVR for those occasions when she complains about my "listening habits." The ability to disable the encoded Dial Normalization setting locally or globally is new to the TV4 device whereas older TV units appear to have simply passed the DialNorm setting through to the user's downstream device for handling. (So, for me, this is less of an issue than the inability of my receiver to automatically decode active matrix encoded AC-3 bitstream content that is no longer being passed to my AVR as an AC-3 bitstream.)
Very informative all the different formats and encodings that need to be supported and surprised to hear the number of issues going directly HDMI into very powerful AV Equipment
As previously indicated, I'm hoping the current absence of passthrough support in tvOS v9.1 "Auto" and "Dolby Surround" modes is merely a prelude to future support of other possible compression formats. However, until full Dolby bitstream passthrough support is restored, I will continue to lament its loss. I see no reason why the previously proven bitstream mode option cannot be restored as a fully supported but separate output option allowing the TV4 to function in the same manner as TV2 and TV3 devices and how the TV4 might have worked under tvOS v9.0 or v9.0.1 if bitstreams were passed to downstream devices directly—without any preprocessing—and thus, not forcing users to find processing workarounds for content normally played properly by downstream devices alone and on their own without being modified by the TV4.
