Z9X 8K v1.3.05 — Incorrect stereo downmix on tracks with C-first channel layout

Hi,


I’m reporting an audio bug on the Z9X 8K, firmware v1.3.05.


When playing MKV files with a multichannel track, the stereo downmix is unbalanced: background music and ambient sounds are clearly shifted to the right channel. Dialogue stays centered, but all surround content goes right.


The problem only happens with tracks whose channel layout starts with the center channel. Example: a DTS-HD MA 7.1 track with layout “C L R LFE Lb Rb Lss Rss” is affected. Files with a standard “L R C LFE Ls Rs” layout are perfectly balanced.


It looks like the downmix uses a fixed channel order instead of reading the declared layout from the file.


Tested:


• Affected: 3.5mm analog output and optical SPDIF output

• Not affected: Bluetooth output, same file, perfectly balanced

• SPDIF and HDMI decoding both set to LPCM 2 channels

• Two different headphones, same result

• Same files play balanced on other devices, so the files are fine

• Audio compatibility mode made no difference


Player: Zidoo Home Theater, local files from USB drive.


Has anyone else noticed this? I can provide a sample or MediaInfo output.


Thanks

 

C, l, r, lfe ?
Wow, never knew it would exist.
Why would someone deviate from the standards?

 

Update: false alarm on my side, sorry for the noise.


After more testing, the issue is not related to the player at all. I confirmed the same right-shifted balance with the exact same file and track on my PC, on the TV’s own optical downmix, and over Bluetooth. So it’s the track’s mix itself, not the Zidoo’s downmix.


To answer your question though: yes, C-first layouts do exist. MediaInfo reported “C L R LFE Lb Rb Lss Rss” on a DTS-HD MA 7.1 track from a Blu-ray remux. It seems to happen with some DTS encodes. But that turned out to be unrelated to my problem.


Thanks for taking the time to reply.