Audio out on ATV is set to Auto. Have also tried to force Dolby Digital 5.1 audio out, but same result.
Audio out on TV is set to either multichannel or bitstream and ARC output to surround receiver. Either way same result.
Problem: Receiver (Onkyo TX-SR608) reports that it receives a Dolby Digital signal on ARC. Playing surround demo on Youtube (or through APP), but either way the audio sent to one of the surround speakers is sent to both front and back. It should have been sent to back speaker only, but it is sent to both front and back.
The YouTube app for the Apple TV box has its quirks for surround sound. First, user content gets published even if faulty or making false claims. Second, it will play in stereo unless you unlock 5.1 while playing a true 5.1 clip.
I would suggest testing your surround speakers with e.g. the Surround Speaker Check app from the tvOS App Store. The free edition is sufficient.
I read somewhere that ATV only output LPCM and it is up to the TV (the man in the middle) to decode the LPCM signal into a Dolby Digital 5.1 bitstream. Is this correct?
With setting Audio Format: Auto, the Apple TV will output in uncompressed LCPM (Multichannel) with the same number of channels as the source it receives, up to 7.1.
With setting Audio Format: Dolby Digital 5.1, the Apple TV will output in compressed Dolby Digital 5.1. It is meant as fallback option for when LPCM Multichannel isn’t supported by other equipment (e.g. for use with Toslink optical audio cable to the audio system).
As I see it, the error is either that the digital processer in the TV is not working correct
Or the TV’s audio output settings aren’t optimal or not correct. If it has a ‘passthrough’ option, then that would be preferable, imho.
or that the audio-out circuit on the ATV is not working.
As that is done in software and the same for every user, this seems very unlikely.
Not sure if your receiver has settings for how to manage/manipulate incoming surround signals or discrete speaker signals, but that is worth checking too. For instance, some receivers have setting for channel upmixing, like for faux surround. Choose for keeping the signal as-is.
