Video playback very laggy and no sound

[nzm]

REPRODUCIBILITY (% or how often): always
BUILD ID = OS VERSION (Settings > About product): 4.3.0.12
HARDWARE (XA2, X10, X10 II, …): X10 II
UI LANGUAGE: German
REGRESSION: (compared to previous public release: Yes, No, ?): Yes (but I noticed this behaviour in 4.2 as well before updating to 4.3, however everything worked ok in earlier versions)

DESCRIPTION:

Video playback is very slow / laggy and has no sound. This affects videos in the Gallery app, but also e.g. videos on Youtube (native browser as well as Opera Android app).

PRECONDITIONS:

STEPS TO REPRODUCE:

1. record a video with camera app
2. try to watch the video in gallery

EXPECTED RESULT:

the video plays in realtime

ACTUAL RESULT:

very slow playback without sound

ADDITIONAL INFORMATION:

I tried this solution

[4.3.0.12] Jolla camera (also torch) does not start at all - as well as videos do not play

Can someone who’s run into this problem test rebuilding just the ssu cache instead of adding the missing repo manually? There’s a bug in ssu that we didn’t think affected public releases, but this is sounding very similar. Remove any Jolla repos (from the section of user added repos) you might have added manually with: ssu rr <repo name> then do: devel-su rm -r /var/cache/ssu/ ssu ur After this, you should see the missing repo (e.g. adaptation-common) in the system repos when you run ssu lr…

(store was listed as user added repository, so I removed it) but it didn’t help

[nzm]

I recently noticed the following: When headphones are connected videos play smoothly and with sound.
What could be the reason for this behaviour? I seem to be the only one with this issue, so is there some way I can check my device for errors?