Remux Dolby Vision Audio becoming PCM

[hed320]

I've also been experciencing this problem over the last two days on my LG C4, were I'm only getting stereo sound when playing my Dolby Vision + Atmos mkv files using Jellyfin, while HDR10 files play fine with surround sound.
After troubleshooting this further today it seems that the remuxing to mp4 is actually causing the issue, if I direct play the files in another way they play just fine, I get the Dolby Vision logo showing up and the surround sound works using my old home theater setup.
After trying way to much other stuff I tried putting the file on a usb stick and the built in mediaplayer of the tv which played the mkv file just fine, the Dolby Vision logo showed up and surround sound worked, to my surprise.

For now I've installed the DLNA plugin on my Jellyfin server so that I can Direct Play the files without Jellyfin trying to remux them, using DLNA should stream the file as is, this works without a problem on my end both DV and surround sound worked.
To install the plugin you open the server dashboard and click on "Catalog" in the left panel, there you should find the DLNA plugin, click on it and install it.
After the plugin has been installed, you need to restart the server to activate the plugin. Then you open the input selection on your tv and you should see a new option with the name of your Jellyfin server to the right of the HDMI inputs (IIRC).

During my troubleshooting I've seen it mentioned quite a few times that LG tv's/WebOS is unable to play DV mkv files. This is not what I observed so maybe this was recently fixed or is unique to newer models or something, I do not know I've only had the tv for a few weeks and I haven't come across useful changelogs for WebOS either.

Furthermore I would like to add that I've not experienced problems with the "Prefer fMP4-HLS Media Container" option checked playing my SDR and HDR10 HEVC (and maybe other) files, having this option checked only was a problem when trying to play the DV mkv files that Jellyfin was still trying to remux.
So perhaps actually Direct streaming these files as the description of this option suggests would also (hopefully) fix that.

Lastly I've also had intermittent stutters/buffering, skipping or the playback stopping completely when I actually tried to watch the remux that Jellyfin is producing, this does not seem to happen when Direct Playing the files, but I'm not yet sure of this as I haven't watched the Direct play long enough.

Based on my experiences you should not play these problematic files using the WebOS app or browser as these methods will be forced to play a remux, and there is currently no way to turn this behaviour off, if it is (still) needed at all.
Hopefully this helps some people.

[DaveR1974]

I also have this issue on my new LG OLED C4. It did not happen on my previous LG TV, SK8500 WebOS 5.50.56, which was able to direct play MKVs with DV without the need to transcode.

I have now tried putting files on USB, and where WebOS 5 worked without issue, WebOS 24 either plays the files with the wrong colours (DV without HDR fallback MKVs) and no DV tag on screen, or uses HDR (DV with HDR fallback MKVs).

As a further test, I manually changed the "mkv" to "mp4" but this had no effect.

Then I tried the rewrap function of Shutter Encoder, but that stripped the DV metadata.

I then found a thread on Reddit that gave instructions on how to get Shutter Encoder to correctly change MKVs to MP4s, preserving the DV data.

After successful USB playback testing on 3 different files, 1 DV only with DDP5.1, 1 DV only with DTSHD-MA and 1 DV with HDR fallback (DDP5.1), I tested via Jellyfin WebOS App.

Success (other than DTSHD-MA being only DTS due to limitations with Jellyfin).

To help others, here is what I did...

Open Shutter Encoder, and add the file/files to be converted.

In the "Choose function" dropdown box (highlighted red in figure 1 and 2), do not choose an option. Instead, enter the following text...

ffmpeg -c copy -strict unofficial

If you have subs in the MKV you wish to include (like forced subs), then enter the following text instead...

ffmpeg -c copy -c:s mov_text -strict unofficial

       

In the dropdown box beside it (highlighted yellow in figure 2 and 3), there will be various options like mp3, but mp4 will not be there. Just type ".mp4"

   

If you wish to save the new file somewhere else (change), add a suffix to the filename or add a subfolder, see the Output options (highlighted in blue in figure 3).

Once you are ready, click "Start function" (highlighted green in figure 4).

   

The speed will depend on various factors, such as how many files you are batch processing, whether you are using the same drive for the new files or a different drive, along with the speed of the drive/drives.

Once done, it is just a matter of ensuring the files are named correctly for Jellyfin as per the FAQ for Movies and TV Shows.

Then you just need to remove the MKV versions from your Jellyfin server, and upload the new MP4 versions.

I hope this helps others.