HDMI ARC delay / popping issue - anyone else?

[wavetomars]

I recently began experiencing consistent issues with the HDMI ARC connection on the Wiim Ultra, and was wondering if anyone else had experienced anything similar?

I am primarily referring to a lag in audio starting when content begins playing, as well as a popping sound right before playback begins. I believe this issue is new (perhaps introduced with a new firmware update?), or was caused by a setting I changed (eg. I only recently enabled the sub out, although I since have tried disabling it to see if it would make a difference), as I didn't notice it before.

My setup is an Apple TV 4K hooked up to an LG C1 which is in turn connected to the Wiim Ultra via ARC. The issue is easy to replicate by playing a track in Apple Music on the Apple TV - any time you choose a new track and hit play, it will take a few seconds for the music to kick in, and it usually begins with a short pop or similar sound.

When I first set up the Wiim, I had some issues with ARC, but thought I had fixed them once I disabled the eARC setting on my TV. Has anyone else had issues, particularly those on the most recent firmware revisions? Thanks!

 

[chebastas]

Hey there,

From what I've noticed that happens when I'm watching Netflix and the audio signal changes from LPCM to Dolby AC3. I don't get the pop but I do get the delay. Dolby also has a delay of about ~500ms which is not present when using LPCM.

 

[Wiimer]

First, make sure your TV's digital audio output is set to PCM. In my previous tests, pop noise occurred when the audio output was bitstream (digital through).

 

[chebastas]

Update: I forced PCM output from the TV, the delay is completely gone but now I get sporadic audio drops. They're short, 1-2 sec drop every hour. Even with the drops it's much better to watch without the delay.

 

[Wiimer]

Update: I forced PCM output from the TV, the delay is completely gone but now I get sporadic audio drops. They're short, 1-2 sec drop every hour. Even with the drops it's much better to watch without the delay.

Support team says the firmware released today resolves this issue. If your device's firmware is not up to date, please wait for an update.

 

[wavetomars]

I followed your advice as well, switching from Bitstream to PCM on the TV. While I initially had some weird audio hangs, after restarting everything, I think those have gotten better. I haven’t had enough time to listen and verify yet, but the pauses/pops at the beginning of songs seem to be gone, so I’m cautiously optimistic! Thanks for your help.

One additional question - is there any quality loss happening when switching to PCM? Is some kind of conversion to the signal happening on the LG C1? Are there changes I should make on the Apple TV 4K? For instance, on the Apple TV, the “Change Format” option under Audio is set to “Off.” according to the tooltip, this means that “Audio will be decoded and sent to your equipment as uncompressed multichannel LPCM. Only change formats if you’re experiencing playback problems.” If I change it to “On” (which then gives me the option to choose “stereo” for the format) it says that “Audio will be re-encoded into a format your audio equipment supports, or replaced with stereo. This may be more compatible, but reduces audio quality.”

I just did a quick test - I switched the Apple TV to “stereo,” and then switched the LG TV back to “Bitstream.” This also seems to correct the issue (haven’t done much testing, but it isn’t hanging at the beginning of songs). So I assume the conversion to PCM is happening on the Apple TV, and the LG is just passing that through. Do you think it makes a difference at what point in the chain that conversion is happening? My instinct is to let it happen on the Apple TV. It does bum me out a bit though that the Apple TV warns me that it “reduces audio quality.”

 

[Wiimer]

I followed your advice as well, switching from Bitstream to PCM on the TV. While I initially had some weird audio hangs, after restarting everything, I think those have gotten better. I haven’t had enough time to listen and verify yet, but the pauses/pops at the beginning of songs seem to be gone, so I’m cautiously optimistic! Thanks for your help.

One additional question - is there any quality loss happening when switching to PCM? Is some kind of conversion to the signal happening on the LG C1? Are there changes I should make on the Apple TV 4K? For instance, on the Apple TV, the “Change Format” option under Audio is set to “Off.” according to the tooltip, this means that “Audio will be decoded and sent to your equipment as uncompressed multichannel LPCM. Only change formats if you’re experiencing playback problems.” If I change it to “On” (which then gives me the option to choose “stereo” for the format) it says that “Audio will be re-encoded into a format your audio equipment supports, or replaced with stereo. This may be more compatible, but reduces audio quality.”

I just did a quick test - I switched the Apple TV to “stereo,” and then switched the LG TV back to “Bitstream.” This also seems to correct the issue (haven’t done much testing, but it isn’t hanging at the beginning of songs). So I assume the conversion to PCM is happening on the Apple TV, and the LG is just passing that through. Do you think it makes a difference at what point in the chain that conversion is happening? My instinct is to let it happen on the Apple TV. It does bum me out a bit though that the Apple TV warns me that it “reduces audio quality.”

I'm no expert and don't have an Apple TV, but I think the audio format is fine in stereo.

"reduces audio quality."

Regarding this, it may mean that the surround sound field effect will be lost.
If you set the Apple TV to "stereo", which sounds louder, "PCM" or "bitstream" on the TV? If they sound the same, I think either one good.