Bug 496596

Summary:	Using External HDMI Device Introduces Severe Audio Latency when Audio Stream in Continuous or near-continuous use.
Product:	[Plasma] plasmashell	Reporter:	hyperspeed1313
Component:	Audio in general	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	NEEDSINFO WAITINGFORINFO
Severity:	normal	CC:	aleixpol, isma.af, nate
Priority:	NOR
Version First Reported In:	6.2.3
Target Milestone:	1.0
Platform:	Fedora RPMs
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description hyperspeed1313 2024-11-22 23:09:54 UTC

SUMMARY
I've observed that when outputting to my TV over HDMI that after ~5-10 minutes of video playback (Netflix, YouTube, etc, Firefox w/ HW video decode) that the audio output will have fallen behind the video output by close to a full second. This can be seen in live playback, the delay in audio stopping/starting compared to video when pausing/unpausing, and the overlapping audio from both the TV and my computer's integrated speakers when changing audio devices from the HDMI output to the laptop's integrated speakers.

If the video is paused and no sound comes out of the HDMI speakers for a while, the A/V sync gradually returns to normal, but once the audio stream is in continuous or near-continuous use again, the latency builds back up.

I have tested the same video content using the same browser in Fedora 41 KDE Spin, KDE Neon, LXDE (Fedora RPM install), XFCE (Fedora RPM install), and Gnome (Fedora RPM install). The issue is only present when using KDE and happens in both Neon and Fedora.

STEPS TO REPRODUCE
1. Connect to external display over HDMI
2. Play video with sound out over HDMI for ~10 minutes

OBSERVED RESULT
Audio stream over HDMI has developed latency of close to 1 second. Audio stream over integrated speakers is unaffected.

EXPECTED RESULT
Audio stream should never accumulate latency over any device.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora 41 KDE Spin, KDE Neon User Edition
KDE Plasma Version: 6.2.3
KDE Frameworks Version: 6.8.0
Qt Version: 6.8.0
Hardware: Framework 13 w/ Ryzen 7840U mainboard, 2.8k 120Hz integrated display.
Display Configuration: Only external HDMI display in use - 3840x2160 @ 60 Hz.

ADDITIONAL INFORMATION

Comment 1 hyperspeed1313 2024-11-22 23:11:33 UTC

Clarification: Gnome Session used was Gnome 47, Wayland.

Comment 2 hyperspeed1313 2024-11-22 23:35:16 UTC

As an additional sanity check to verify it's specifically an HDMI problem, I've now verified the problem doesn't happen with my DisplayPort desk monitors.

Comment 3 Nate Graham 2025-12-09 19:59:16 UTC

Sorry to hear about this. Unfortunately the bug report ended up somewhere weird, so it was overlooked. Now it's in the right place. Can I ask you to check and see if this is still happening with Plasma 6.5.3 or later? Thanks a lot!

Comment 4 Bug Janitor Service 2025-12-24 03:46:25 UTC

🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information, then set the bug status to REPORTED. If there is no change for at least 30 days, it will be automatically closed as RESOLVED WORKSFORME.

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