https://bugs.kde.org/show_bug.cgi?id=524319
Bug ID: 524319
Summary: [Intel/i915][Wayland][EDR] Severe video frame drops
depend on color depth, RGB range and color accuracy
settings
Classification: Plasma
Product: kwin
Version First 6.7.4
Reported In:
Platform: Neon
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: platform-drm
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: ---
Created attachment 195187
--> https://bugs.kde.org/attachment.cgi?id=195187&action=edit
Sanitized mpv trace log reproducing EDR-related frame drops
DESCRIPTION
With EDR enabled on the internal Intel/i915 eDP display, hardware-accelerated
video playback in mpv drops frames depending on the Plasma display color
settings.
The issue is reproducible with a 10-bit HEVC HLG/BT.2020 video
(1920x1080, about 59.98 fps).
With EDR disabled, playback is smooth.
With EDR enabled, smooth playback requires this combination:
- Maximum color depth: 12 bits per color
- RGB range: Full
- Color accuracy: Prefer color accuracy
Selecting "Prefer efficiency" makes the problem much worse and causes
hundreds of dropped frames.
STEPS TO REPRODUCE
1. Use Plasma Wayland with the internal display set to
3200x2000 @ 120 Hz.
2. Enable EDR in Display Configuration.
3. Play a 10-bit HEVC HLG/BT.2020 video with:
mpv --no-config --hwdec=vaapi --vo=gpu-next --gpu-api=opengl video.mp4
4. Compare these display settings:
EDR OFF + RGB Auto -> OK
EDR OFF + RGB Full -> OK
EDR ON + BPC Auto + RGB Auto -> frame drops
EDR ON + BPC Auto + RGB Full -> frame drops
EDR ON + BPC 12 + RGB Auto -> frame drops
EDR ON + BPC 12 + RGB Full -> OK
5. With EDR enabled, select "Prefer efficiency" under Color accuracy.
This makes the problem dramatically worse and causes hundreds of
dropped frames.
6. Selecting "Prefer color accuracy" together with BPC 12 and RGB Full
restores smooth playback.
OBSERVED RESULT
The same video and the same mpv command can change between smooth playback
and severe frame dropping depending only on Plasma display/color settings.
With some EDR configurations mpv drops many frames. Selecting
"Prefer efficiency" can increase this to hundreds of dropped frames.
Disabling audio does not eliminate the problem.
Using:
--target-colorspace-hint=no
also eliminates the frame drops.
EXPECTED RESULT
Enabling EDR or changing color depth, RGB range, or the Color accuracy
preference should not cause severe frame dropping during hardware-accelerated
video playback.
"Prefer efficiency" should not perform dramatically worse than
"Prefer color accuracy".
SOFTWARE/OS VERSIONS
Operating System: KDE neon User Edition
KDE Plasma Version: 6.7.4
KDE Frameworks Version: 6.28.0
Qt Version: 6.11.1
Kernel Version: 7.0.0-28-generic (64-bit)
Graphics Platform: Wayland
ADDITIONAL INFORMATION
CPU: 13th Gen Intel Core i5-13420H
GPU: Intel Graphics / Raptor Lake-P
Kernel driver: i915
Memory: 16 GiB RAM
Display: internal eDP-1
Resolution: 3200x2000 @ 120 Hz
Scale: 170 %
Mesa: 25.2.8
mpv: v0.41.0-926-ge034d612c
libplacebo: 7.371.0
FFmpeg: 6.1.1
Hardware decoding: VA-API / Intel iHD
The active display pipeline was checked with i915 debugfs.
In the working configuration:
i915_current_bpc:
Current: 10
i915_display_info:
pipe src=3200x2000+0+0, dither=no, bpp=30
port_clock=810000, lane_count=4
DRM connector properties with EDR enabled, BPC 12 and RGB Full:
Broadcast RGB = Full
max bpc = 12
Colorspace = Default
HDR_OUTPUT_METADATA = empty
An interesting observation is that Plasma "Auto" color depth and explicit
"12 bit" both result in:
max bpc = 12
and the actual active display pipeline remains:
Current BPC = 10
bpp = 30
However, playback behavior is different between Auto and explicit 12-bit
selection when EDR is enabled.
I have attached an mpv trace log (mpv-startup-short.log) recorded while
reproducing the frame drops.
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