Dolby TrueHD problem

My setup is the following.
Vero4k connected to LG C7 OLED through HDMI to deliver HDR video as my Yamaha V379 reveiver doesn’t support HDR.
Vero4k connected to the Yamaha V379 receiver through an optical cabel to transfer the audio.
Yamaha V379 receiver connected to LG C7 OLED through HDMI to transfer the audio.

Even though the Yamaha v379 receiver could decode TrueHD the bandwidth is limited as I need to use an optical cable to transfer the audio from the Vero4k as the only HDMI out on it is connected to the TV directly.

So I know it’s not possible to get TrueHD and HDR both on the same time with my setup but I know it was possible to still get sound from TrueHD streams in a way that Kodi converted it real time to 16 bit audio.
For some reason this doesn’t work for me no matter if I set in the audio options in Kodi that my Receiver can or cannot decode TrueHD.
I don’t get any sound with both settings.

Any idea how to solve this ? I’m using a build from 04.2019.

I’ve just saw that a relevant bug was fixed in 18.4

  • Fix PAPlayer to handle passthrough for TrueHD (audio)

Any ETA to get this on the Vero4k ?

PAPlayer is Kodi’s audio player and isn’t used for video playback.
The Kodi changes would impact playing music.

For your issue, it would be good to see logs to see how you have configured your audio. You would be better off enabling passthrough and relying on the core to be passed via SPDIF. LPCM is limited to 2 channels on optical, so isn’t ideal.

I will provide the logs when I get home thx Sam.
Passthrough is enabled I know that for sure. And I also know that it did work with the very same setup just as you say in a way that the core of the HD stream was passed via SPDIF.

No idea what changed now that I moved to an other house.

TrueHD doesn’t have a core, and unless the container format is M2TS, there won’t be a Dolby Digital compatibility stream on the same track, so you’d have to pick a different track.

It’s possible there are some tools that keep the two streams on one track, but the more recent (over the last year or so) MKVtoolnix libraries separate out the two streams into different tracks.

All my files are in mkv format. If TrueHD doesn’t have a core to be passed to SPDIF then I’m not sure how it was possible to hear the HD stream until recently. Maybe Kodi was converting it real time to 16 bit. Or is that not possible ?

AC3 transcoding is probably the best option then.

Not sure what you expect the second one to do. Is this ARC?

We do have a commandline switch to fool AVRs into accepting HDR. It works with my V373 except I do get issues with banding on some videos. Not sure why. If you want to try that:

echo 1 | sudo tee /sys/class/amhdmitx/amhdmitx0/force_hdr

My V373 doesn’t support 4k60Hz video (plays at 1080p but with HDR :slight_smile: ) but 4k24Hz works.

I see your 379 does do 4k60Hz so it will be interesting to see if this works. You can make the setting permanent with rc.local.

Depending on how they were created, there may be a Dolby Digital 5.1 track in the MKV file. It would usually be the next track right after the TrueHD track.

If there isn’t, you can create the track (eac3to does this well) and then mux it in. Something like:

eac3to MyMovie.mkv 2:"MyMovie.ac3" -640

Then, use MKV tools to add the AC-3 track.

Can Kodi do this real time ? I don’t want to convert manually.

Wow can’t wait to try this tonight. Thanks :grin:

Yes – it should be able to do this on the fly. That will get you a 5.1 track which can be sent via SPDIF.


And make sure you set your audio settings according to this:

Tiny question: The LG C7 is able to forward Dolby ATMOS or Dolby TrueHD to the Audio Return Channels, isn’t it?

Addition: Could be that even if the TV is capable to this the AVR needs eARC cap and HDMI 2.1 to process lossy Dolby Atmos and might be lossless HD formats like TrueHD.

@JimKnopf Seems like this isn’t possible with standard ARC, but it is with eARC.

On last year’s LG 7 and 2018 8 Series OLED TVs and some Super UHD LED-LCD TV models with Dolby Atmos you can send the decoded Atmos surround information in the TV out over the HDMI ARC connector, but only when the signal is carried in a lossy Dolby Digital+ surround sound stream.