Trouble with TV audio passthrough (1 Viewer)

[Jon Dart]

I have an odd problem. My home theatre setup consists of a Yamaha HTR-5640 receiver (pre-HDMI), an LG 50" LCD TV 50LS4000 (not a smart TV), blu ray player and a Chromebox set up with Libreelec 8.2.4/Kodi Krypton 17.6. Because the receiver has no HDMI connections, and only 1 Toslink input, I have the Chromebox and the Blu Ray player connected via HDMI to the TV and the TV Toslink out to the receiver Toslink in. The odd thing is that when I play movies in Kodi, or watch live local TV, the TV passes the 5.1 audio signal to the receiver, no problem. I get Dolby Digital or DTS. But the TV refuses to pass the Blu Ray's bitstream or DTS encoded signal to the receiver; the receiver says it's only receiving PCM. I've switched the HDMI cables around to different inputs on the TV, and even tried different HDMI cables, and still no luck (TV speakers are set to "off"). I've even down-rezed the sample rate from the Blu Ray player. When I connect the Blu Ray player directly to the receiver, no problem getting surround sound. Why would the TV discriminate? The further wrinkle is that occasionally I hook a Chromecast into the TV as well, and same thing, just PCM audio gets passed to the receiver, but the Chromecast seems to be aware of whatever the TV seems to be doing, because even with the newest movies the Chromecast only offers 2-channel stereo. Anyone know what might be happening? Why would the TV pass the full Kodibox and TV 5.1 surround audio stream to the receiver, but not the surround stream from the Blu Ray player or the Chromecast? Thanks

 

[Wayne A. Pflughaupt]

But the TV refuses to pass the Blu Ray's bitstream or DTS encoded signal to the receiver; the receiver says it's only receiving PCM. I

That is correct, TV’s don’t pass-through DD. Not entirely sure, but I think it’s because the TV “breaks down” the HDMI signal into audio and video it can use itself, for the display and built-in speakers. But the TV does not have the capability to re-encode the audio back into DD.

You can solve this problem by upgrading your receiver, or downgrading your source components to vintage models that have outputs the HTR-5640 can use.

Regards,
Wayne A. Pflughaupt

 

[JohnRice]

I read this last night and was a little puzzled, but then something occurred to me. 99% of the time, Wayne's response is correct, but there are some TVs that pass DD (and I suppose DTS) to the optical output from sources plugged into hdmi inputs. First, all TVs pass DD from their built-in tuners. So that explains why it works that way. What had me confused is that you say the Chrome Cast gives you DD 5.1 from the optical output, but not the BR player. That indicates your TV is one that does pass DD 5.1.

So, what would explain everything is if your BR player is set to output bitstream through hdmi. That means the TV is receiving an HD audio signal, which can't be passed through the optical output, so the TV is downmixing it to 2 channel PCM. When you connect the player directly to the receiver, you get DD/DTS because the player outputs that by default to optical, because optical can't pass HD audio.

So, I think your solution is to make certain the audio output (in the player's setup menu) is set to DD/DTS rather than bitstream. The options vary with brand. Then it should only send a compatible signal to the TV, which it can pass on.