AAC Passthrough from TV to AVR not working

Hi folks.

Firstly I’m almost certain this isn’t an OSMC issue (unless the thread I just read concerning no. of channels not necessarily being related to no. of speakers is part of the problem) Just hoping that some kind soul might be able to think up something I’ve not already tried.

The situation is that when playing any AAC encoded video with the TV in multichannel bypass mode (which I believe should just send the audio stream to the amp) results in no sound. All other formats are fine in this mode. The TV can decode AAC by itself no problem, but just doesn’t seem to be sending it in bypass mode. In multichannel (non bypass) mode where I believe the TV is doing the decoding itself before sending it to the amp, there is an annoying quirk where centre channel audio is sometimes sent to the rear left speaker until I press the source button on the TV until it goes to the correct one.

I swear I’ve have had this working briefly before but when changing to a differently encoded file it stopped. Rebooted all devices but couldn’t get it working again.

I realise a simple fix for this would just be to connect the Vero to the AVR, however from previous experience my AVR and TV do not play well when it comes to auto input switching and I’m trying to keep the system to just one remote for ease of use for other family members.

My setup is as follows… Phillips 55OLED856 connected to Pioneer VSX 930 AVR via HDMI from eARC enabled port on TV. Vero V connected to TV via HDMI.

The settings on the AVR are HDMI CEC enabled, control enabled. (There’s very little related I can see on this end).

The audio settings on the TV under Sound>Advanced are, eARC - off, Digital out format - Multichannel (bypass).

The Vero settings under Audio are, Audio output device - HDMI, Number of channels - 7.1 (I only have 5 speakers with no sub, but have tried every setting with no effect) Output configuration - Best match, Stereo upmix - disabled, Resample quality - Medium, Keep audio device alive - 1 min, Allow passthrough - enabled, Passthrough output device - HDMI, Dolby Digital AC3, Dolby Digital Plus E-AC3, DTS, TrueHD, DTS-HD - all enabled.

Any assistance gratefully received!

That Amp supports 4k on its HDMI connectors so why would you not connect the Vero directly to it?
EArc will always give you worse sound options

Unfortunately AAC passthrough hasn’t (and likely never will) be a thing.

The TV and the amp don’t play well together. I have my PC plugged into the same amp and it can sometimes take multiple reboots of it before the TV will show any display from it.

If I don’t get anywhere with solving this problem with the TV in multichannel bypass mode then I might have to bite the bullet and rewire everything but would prefer not to (everything neat and cable tied right now!)

If I would have spent that money on an amplifier then I would surely spend the effort to get the best out of it and EARC will never give you that.

Fair comment about the benefits of connecting the Vero direct to the amp. I can’t remember why I had it connected to the TV before (possibly an A/V sync issue) but that when I was using a 4K+ on older FW and the TV has since had at least 5 FW updates as well.

I’ve rewired everything this afternoon and everything looks/sounds good so far. I’m still not exactly sure what all the audio settings in OSMC expert mode relate to (particularly channels) as currently I have it set to 2.0, with upscale stereo enabled as well (I have a 5.0 speaker set up if relevant) and this means that any video file encoded in stereo will show as Dolby Digital on the amp. Whereas any other channel setting, 5.0/5.1/7.1 etc it will show as PCM.

I get that this is expected behaviour, I’m just trying to understand the logic behind the channels setting.

If anyone could enlighten me and confirm if this graphic I found on the forum dating back to 2015 is still relevant that’d be great.

The “channels” means PCM channels which is roughly analogous to analog audio patch cables with two channels being like a stereo pair and 5.1 being six cables. Different devices support different numbers of PCM channels and that setting sets the maximum number of channels that it will output. If your source isn’t in a format that is covered in the enabled passthrough options, and it has more channels than what the channels setting is set to, then your output will be resampled into the number set in that setting.

There is an audio guide on this sight that may provide further insight…

Thank you, I definitely understand what’s going on better after reading through that.

However, the reason the Vero was attached directly to the TV has quickly become apparent again.

The TV and amp have terrible CEC integration (I’m going to blame the TV) as when you select the HDMI source for the amp, you never know what is actually going to appear on screen. The blu-ray may power on, possibly the PlayStation. It will even populate the sources list with double entries for the same source (as the devices are in the amp’s subset of course), sometimes even overwriting the source label with the last device it decided to try and talk to.

I know I said in the OP that the TV had had approx. 5 FW updates since I originally connected the Vero when I bought it, so would have thought Philips would have sorted this by now. No options for telling it that an HDMI equipped amp is attached that I can see, either!

That should be handled automatically by CEC as it would register itself on the CEC bus as an amplifier type device. A simplified explanation of how it works is there is a single pin on the HDMI cable that all the connected CEC devices talk on. The display/TV (when it is connected on enabled) acts as the master arbitrator but it relies on all the connected devices to behave and play by the rules as it can’t force any devices to do anything. There is polling done where devices get assignments (player1, recorder2, amp1, etc.) and report where they are connected. If there is a device that is responding or talking as somewhere, or something, that it is not then the whole automagically does stuff breaks down. In the same vein if a TV or AVR gets stuck with incorrect/outdated device info then it can wind up doing things wrong. Also another device can be stupid and when it sees something else happening can cause issues (think player1 tells TV to turn on and switch to it then player2 sees the TV turn on and that triggers it to say switch to it). Additionally if your using eARC then displays or AVR’s may have only a single connection that must be used when that is enabled. For example on my LG TV’s if I connect my eARC enabled AVR to anything other than HDMI port 2 when CEC does a video input switch it doesn’t work as it switches to port 2 (where it expects the AVR to be) instead of where the AVR had said it was plugged in.

To try to work through these issues usually the first step should be to unplug all CEC devices from the wall for a minute to get a fresh start on device assignments. If you have an AVR it might also need a soft reset as well (I’ve seen this with my Denon AVR). If the problem persists from that point it is probably easiest to then narrow the number of connected devices and add them back one at a time til you find the bad actor. This might need to be done by pulling the HDMI cable from the devices and not the power cable as some devices will interfere with the CEC bus if they are connected but unpowered. Once you find the problem device then it is probably a matter of seeing what configuration options are available and trying different things.

As for the Kodi/OSMC CEC settings available they can be found in settings>system>input>peripherals>.

Thanks very much for the detailed response. I’m aware of the Kodi/OSMC CEC settings and believe I’ve got them set right (basically enabled but doesn’t tell any other devices to do anything).

As for troubleshooting CEC as a whole, I’ll try and find some time when I can strip the system down, but having messed with it for a good while last time, I think it is just an annoying quirk of the TV. I might shoot an email to Philips and see what they have to say.

Lastly I think I’m right in saying there are some CEC commands you can issue on Pi / Vero to see whats going on isn’t there?

You can turn on debugging for the CEC. I think that prints all the messages on the CEC bus.

Ah that’s a good shout. I was thinking SSH commands though, I’ll have a look about.

Turn on debugging, ssh in and tail -f ~/.kodi/temp/kodi.log to see what’s happening.

You can get the messages using cec-client but since that breaks the connection to Kodi until you restart mediacenter it would probably be more useful to tail the log like Grahamh suggested. You could pipe that into grep if it is a too noisy.

Also in Kodi’s CEC settings make sure you tell it is plugged into the amplifier if that is how you have it connected. Not having that setting correct can make it switch wrong.

You might want to consider getting a programmable remote, such as a one-for-all, (with a JP1 pin) rather than trying to rely on CEC (which can be problematic with some devices as you’ve discovered)
You can then program the remote to send macros to set all of your devices to the appropriate inputs when you want to switch devices, and make each button do exactly what you want on exactly the device you want to do it on. (see JP1 Remotes) for some info on programmable remotes)
Then you could stop worrying about your TV’s (or Reciever’s) broken CEC and just connect everything to the amp and get the best sound out of it.