Until now I've been an ARC/HDMI/CEC unicorn. My Panasonic plasma worked faultlessly with my Onkyo, ARC worked, was always perfectly in sync, amp turned on and off with the TV.

With my LG OLED and my old Onkyo, everything worked just as well (I have the Apple TV and blu-ray player plugged into the TV and send the audio for everything to the amp via ARC).

With my LG OLED and my newer Onkyo (beefier amp and a REL sub), everything worked just* as well.

Until now. For some reason over the last few weeks ARC has been failing. We'll turn the TV on, starting playing stuff and no sound will come out of the amp. The amp still thinks it has an ARC connection, the TV still thinks it is sending audio over ARC, but nothing happens. Sometimes soft power cycling the amp fixes it. Sometimes hard power cycling the amp fixes it. Sometimes neither does, but the ARC connection starts working again 10 minutes later.

The TV is set to auto update the firmware, I suspect LG have broken something.

I'm bored with trying to fix it now. I've just ordered an optical cable, hopefully removing HDMI/ARC from the equation will fix it (though the amp isn't going to turn off with the TV anymore).

So, turns out everyone is right, ARC/HDMI/CEC is a steaming pile of unreliable non standardised crap (though it did all work flawlessly for me for about 19 years)

* ok, there was one new issue, the Apple TV when playing back 24p video would get out of sync with audio, but I managed to fix that

I turned off HDMI/CEC on my Samsung TV when I discovered that the Xbox kept turning it on (and leaving it on) at random times (presumably when polling for updates while "off").

I have found that those particular HDMI "features" can be flaky depending on the components.

My GF has an Onkyo TX-SR33. It will work fine for a while, and then every once in a while (every couple weeks), the HDMI-CEC features will stop working. By this I mean: Turning on a device won't turn on the TV and switch to the correct input on the Onkyo, I must pick up its remote and turn on the TV and switch it to the correct input.

When the CEC features stop working, the only thing that will get them functioning again is a power cycle of the Onkyo. And I don't mean "pick up its remote and turn it on and off again", that doesn't work, because the on/off on that thing is actually just a "standby". No, I mean that I must physically unplug the thing to get it to fully reboot. Then the CEC features work again for another week or two.

I have another Onkyo at home in the living room, a TX-NR686, that I haven't had any trouble with, but I must admit that I haven't used its CEC features because I'm using a Harmony remote in that location and I don't need those features.

I interpret this as: Embedded firmware for complex systems is hard to make reliable. We looked for firmware updates for the flaky model a while back, but there weren't any. I should check again some time.

If that optical cable is going from your TV to the receiver (sending TV sound to the amp), you might run into something I've seen a lot of TVs do: The optical connection from the TV might only send 2-channel stereo, with no way to get surround sound out of it.

Hard to find data on which TVs have that "feature" and which ones don't. Makes buying new TVs tricky.

The TX-NR686 is just happens to be the new one I have.

And yeah, I'll have to keep and eye on what is coming out of the optical link.

I generally like that 686 so far. Though it has some audio-network-sharing features I wish I could turn off, like its built-in Chromecast feature. Since that Chromecast feature is audio-only, no one in our household ever casts to it, and it just clutters up the list of available Chromecasts. Occasionally someone mistakenly tries to cast a YouTube video to it, and doing so changes the input.

One "cheap" solution to the CEC issue is what I've implemented on that older Onkyo at the GF's house: A remote christmas-lights-controller switch. Lets me bounce the power on the sucker without having to dig at the rat's nest of wires back there. Any time I have troubles with the CEC, it's two button presses on that fob. It sucks having to keep that fob at the couch, but it beats spelunking for the plug every couple of weeks.

I'd buy a different stereo to replace it, but I have no guarantee a different one won't encounter the same CEC problems. Especially since you have evidence that the problem could be (at least partially) due to the TV at the other end of the wire.

My recent model LG LED TV does pass full 5.1 down the optical cable, so perhaps Andy's LG should be okay in that regard.

My new Yamaha AV Receiver arrived earlier this week, and sure enough there was a pending update (from this past spring) awaiting it. The release notes said they were fixing something to do with ARC.

As for CEC, I've never used it to date, but have now ordered a CEC splitter so that I can code my MythTV box to automatically power the receiver on/off, and also [EDIT] so the MythTV box/remote can signal volume up/down to the receiver. [/EDIT] I'll let y'all know how that works out once I receive and configure it.

My Harmony will randomly stop turning the receiver off (Denon AVR-X6200W). Then, a few days later, it will magically start working again. It is rare that it stops turning it off though.

The problem I'm having sadly can't be addressed like that. Powering of the amp only sometimes fixes it (and power cycling the TV never appears to fix it).

Today it got worse:

- turned on TV
- no sound
- tried power cycling amp
- no sound
- switched TV to internal speaker
- watched YouTube for a couple of minutes
- TV switched back to ARC by itself
- no sound

ARGH

To further taunt me, I've noticed that the amp displays "TV speaker" when you change the TV to internal speaker, so there is clearly communication going on between them.

In my case I don't really want to use any fancy features of the 686. I want it to just be a dumb decoder and amp. I'm not even using its input switching (as we really like the LG interface for all that). Sadly it and the TV combined are somehow failing to achieve that now for some unknown reason

While Googling I found this wonderful misguided advice:

"they build up a negative charge and it prevents the receiver from communicating with your TV. The solution is to unplug your TV and press the power button. this discharges and returns to neutral the port. Turn on your tv and the receiver and the TV should pick it up."

It occurs to me if the toslink works we are back to the bad old days of using a separate removte to change the volume

I think the "usual" or "intended" solution is to use the amplifier's remote for everything. But that does require working CEC and (likely) also ARC. And it assumes the amp's remote has CEC buttons to use for channel changing on the TV.

Oh, and it ignores the modern reality for many folks who want to use the "smart" app features of their TV.

Pretty much all our watching is done in the apps on the TV, so we’ll be stuck with using two remotes, the really excellent LG remote and the remote for the amp. Which will be a real step backwards from being able to use just the LG remote

I've done a fair bit more Googling and have come across plenty of people with basically the same problem "ARC worked fine between my LG and Onkyo, until it started working intermittently".

I keep finding new variations on things that will fix it. Latest one was switching the TV from ARC, back to internal speaker, back to ARC. Fixed.

Ten minutes later during more testing, ARC not working again. Switching between ARC/TV speaker didn't fix it.

One of the most frustratingly random bugs I've come across

In good news, it would appear that the LG Magic Remote can also be used to control the amp via IR (at the moment all the amp control is via HDMI/CEC, which won't work when I switch to an optical cable).

Oh, that could be useful. I may try that here too. Thanks!

I've got the optical cable in place now.

It is definitely sending 5.1 sound to the amp. However the amp is labelling it all as Dolby Digital Surround 5.1, whatever app/source it is coming from.

With HDMI/ARC I was getting Dolby Atmos and the like passed through to the amp, which of course isn't going to happen over the optical link.

So I guess I might end up plugging the Apple TV and Bluray into the amp, losing all the nice LG input switching UI

Also, I haven't done any significant testing of lip sync yet, which I'm guessing could easily be an issue too without the HDMI/CEC/ARC "magic".

I wish I could go back to a month ago, where it was all just working correctly like it had for the last 14 months.

*sigh*

I remember what my "entertainment system" was like just a few* years ago. It was a 19" black and white television and we had two whole channels to choose from. If you wanted TV after midnight you were out of luck.

To change the channel you got off the couch, walked across the room, and turned a big knob that went clunk-clunk-clunk. Same thing (but without the clunks) to turn it on or off or adjust the volume. If you were feeling brave and adventuresome, you could open the little panel at the bottom of the set and play with the vertical hold knob to keep the image from rolling over and over.

Hmmm... maybe the Good Old Days weren't all that great.

tanstaafl.

*a few in this case is 65 years. Seems like yesterday to me.

Pah.

You should have tried the UK, where we didn't get a forth TV channel until 1982

We got our first colour TV in 1983.

The Yamaha AVR I have here has a "AUTO Lipsync" setting which it says is "for use with TVs that support Lipsync." Dunno what it does, as I don't currently use the LG TV as anything but a big monitor for my (mythtv) PVR.

Perhaps your AVR has a similar setting?

Yes, there is lip sync stuff on both TV and amp. But my understanding is that all of that happens over HDMI and not on optical.

I don't know whether it is an issue yet, not watched enough varied content to test it.

We got our third channel in 1971, and when I left Alaska in 2008 that's still all we had.

There was a pay television deal that had one channel that played HBO movies where you had to have a little microwave dish on your roof and a down converter to change the signal into something your TV could understand. It was about $70 a month as I recall. That one started up in the mid 1970's.

The TV stations started broadcasting in color in 1967.

tanstaafl.

I've a Samsung bluray player connected to a Samsung soundbar connected to a Samsung TV all via HDMI. Everything powers on just fine with click of a single button, then the soundbar will switch inputs to D.in and I have to fumble for the soundbar remote.

It boggles my mind that in 2020 we're still trying to figure out how to control all of our home theater devices, and they all feel like kludges of one kind or another.

I've never had much luck with ARC/CEC, either with my own equipment or the stuff I set up for clients. I usually avoid the ARC port altogether if it's not the only one with the highest output quality.

Ever since I found the Logitech Harmony Smart Control I've been a happy camper. Sadly, it looks like they're phasing out that model in favor of fancier remotes with features I don't need.

The problem is that ARC always is the highest quality output. I’m not aware of any other way to get DTS/Atmos etc to the amp ?

Why not plug your inputs into the receiver instead?

Because using the LG TV and Magic remote is much more pleasant for switching inputs.

Okay, my HDMI dongle arrived yesterday, so this afternoon was the initial session to try CEC/ARC etc.

First problem: ARC was unreliable. It would work in about 8 second bursts.. turned out to be a cabling issue. I replaced the skinny HDMI cable with a pair of thicker ones and a coupler to join them for the needed length. Problem solved.

Then I inserted the HDMI/CEC dongle in place of the coupler, and with a small amount of scripting and an hour or so of time.. I got the MythTV box to control the AVR's volume/mute over CEC. Yay!

Power on/off and input switching also seem to work with simple commands over the CEC tap (USB interface to MythTV box).

So I'm back to a single remote control for everything here again. Not that that helps Andy.

OMG! OMG! It is actually ultrasound! And, no battery! Mechanical. I am in such disbelief that such a thing actually existed.