Z9X video stuttering in conjunction with DTS, FLAC, PCM tracks

I've noticed a pretty weird issue with videos containing DTS-tracks:

The video format (UHD in H.265 or HD in H.264) doesn't seem to matter much as both movies such as "Sleepy Hollow" (UHD) or "The Fly" (HD) are equally affected. As soon as I select the DTS audio track included, I get random videos stutters, most apparent during the scrolling end titles. Interestingly, the audio itself is flawless.

Furthermore, it occurs with the DTS-HD MA track (the core extracted during playback or downmixed to stereo PCM) and also when I extract the DTS-core beforehand, remux it back to the MKV-container and play it.

(E)AC3 or AAC don't seem to cause the issue.

Considering that DTS-tracks are very common now (some might remember the dark days were DVD player's at first didn't support it) and as trivial as it gets, this issue is extremely weird.

I've also tried the most recent beta firmware (v6.4.62) but it behaves just like the v6.4.42.

 

You need to provide a bit more info... most importantly what are you sending the audio to? A TV, a full lossless cabable receiver? a soundbar? etc. And are these files your own rips or downloaded?

 

sounds a lot more like a network issue (wifi maybe?) with the higher bitrate audio. Does it do the same if the files are played from an attached HDD or USB flash drive?

 

Thanks for your replies. I did further testing and while Phil181's suggestion goes in the right direction, it doesn't seem to be an issue with the data rate provided by the source.
Insights:

- the same issue occurs when I copy the file to a directly attached USB stick (faster than required to be of course).

- it is not an issue with DTS per se as I assumed at first because the same issue occurs when I let it decode it to multichannel PCM or FLAC and play one of those tracks.

- remuxing it to a transport stream container with DTS-HD as well, reduces the moments of judder, but they are still present.

- at least in my last test, the DTS core-only variant played fine whereas the DTS-HD one doesn't. That I remembered differently from the whole movie, but for the last end titles part it was fine.

- any devices in the chain can be ruled out as the same occurs when connecting the player directly to the TV, nor does it matter whether the audio gets decoded or bitstreamed.

To me, it seems that the stutter occurs due to player internal demultiplexing and maybe bitrate limitations, which however doesn't explain that videos with a rather low audio bitrate in e.g. AAC together with high bitrate UHD H.265 video still plays fine.

Transfer limitations I'd rule out as it doesn't make any technical sense that within one file, one selected (somehow processes) track falls back on the video rendering while the other doesn't, considering that there is always an entire bitstream sent to the player and demultiplexed there, no matter what gets eventually played. This is also supported by the fact that I could take dozens of DTS-core copies into the Mastroska container, bumping up the total data rate, without any issue.