HDMI audio cut out when changing TV channels

davmol

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Aug 22, 2024
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Hi, I have an Lg TV with hdmi audio out to the WiiM ultra. The WiiM is running to a topping DX5II dac via usb and then on to a pair of Fosi V3 mono amplifiers. Every time I change channel on the TV, there is an approx 2 second delay between the new channel appearing and the audio then returning. I'm wondering if anyone has experienced this issue and how it was resolved?

On a separate note, something similar happens when I listen to music (not via the TV) and toggle the subwoofer off and on again. Each time there is also an approx 2 second delay, so I'm wondering if there is some latency related to USB out to external dac. Maybe I should try running optical out to the dac (instead of usb) and see if the delay disappears? I'll check my DAC settings as well, maybe there is some signal sensing in there as well.
 
The short gap in sound is likely the HDMI Handshake performed because your TV is changing the signalling rate or codec between channels. There may be a setting on your LG TV to force a single format to all output.
 
I agree. Codec change. Depending on the TV channel you are watching you might be recieving simple stereo PCM or anything up to Dolby Digital. When these formats change you get audible signal dropout temporarily. On the sub woofer are you toggling inside the WiiM app?
 
If I switch to PCM output then the delay does go away, and I have also tried all other settings on the TV e.g. fixed DTV defaults, eARC on/off, Passthrough vs Auto, latency bypass, but nothing removes the delay apart from setting output to PCM. Prior to the WiiM Ultra I was using a JBL Soundbar with the same TV and HDMI ARC and there was no such audio delay present when changing channels (with TV output set to passthrough), so is this a WiiM specific issue? It's not ideal having the Dolby Digital Streams downmixed to PCM but this is not my main TV set, so I don't use it much and I can live with it (the Ultra is mainly used for hifi audio).

One additional note on the TV output delay, I notice that the Ultra briefly "pauses" (icon on screen) and then immediately resumes, which is when the audio starts again. I have tried settings on the WiiM side, such as different group delay settings and auto sensing options on/off but they make no difference, the delay is still present.

I don't want to distract too much with regards the sub on/off delay, but yes I am switching it in the app. I can toggle on things like speakers output bass and there is no delay in playback, but when toggling the sub on/off there is the same 2-3 second gap as with changing channels. This isn't a problem though because I rarely turn sub on and off during playback, and I was just mentioning it as I wondered if the sub delay and channel change delay both related to the use of the USB external DAC. I think I will try optical anyway, just to see if this resolves one or both delays.
 
So I tried optical output to the DAC (instead of USB) and this did remove the delay when toggling the sub on and off within the app, but made no difference to the TV channel changing delay. I also tried optical out from the TV and into the Ultra, but it made no difference, and I still had to set optical output to PCM in order to prevent the 2-3 second audio delay whenever I change channel. So I guess my TV and the WiiM just don't get on, but luckily I rarely watch this TV, so I can live with it.
 
So I tried optical output to the DAC (instead of USB) and this did remove the delay when toggling the sub on and off within the app, but made no difference to the TV channel changing delay. I also tried optical out from the TV and into the Ultra, but it made no difference, and I still had to set optical output to PCM in order to prevent the 2-3 second audio delay whenever I change channel. So I guess my TV and the WiiM just don't get on, but luckily I rarely watch this TV, so I can live with it.
Incidentally, have you turned off 'Reduce Noise from Optical/HDMI ARC' in the audio input settings? If this is enabled, it may cause latency.
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