vo_gpu_next: interpolation is flickering

[kasper93]

mpv Information

mpv v0.39.0-577-gf258f54602-dirty Copyright © 2000-2024 mpv/MPlayer/mplayer2 projects
 built on Dec 13 2024 14:39:24
libplacebo version: v7.350.0 (v7.349.0-55-gc03be3f9)
FFmpeg version: N-118064-gd39bac7673
FFmpeg library versions:
   libavcodec      61.26.100
   libavdevice     61.4.100
   libavfilter     10.6.101
   libavformat     61.9.100
   libavutil       59.49.100
   libswresample   5.4.100
   libswscale      8.12.100

Important Information

- Platform version: ALL
- GPU model, driver and version: ALL
- Source of mpv: built from source
- Latest known working version: 0.29.1

Reproduction Steps

Flickers:

mpv -v sample.mkv --no-config --profile=high-quality --dscale=catmull_rom --video-sync=display-resample --interpolation --tscale=sphinx --tscale-blur=0.6991556596428412 --tscale-radius=0.56 --tscale-clamp=0.0 --vo=gpu-next

Doesn't flicker:

mpv -v sample.mkv --no-config --profile=high-quality --dscale=catmull_rom --video-sync=display-resample --interpolation --tscale=sphinx --tscale-blur=0.6991556596428412 --tscale-radius=0.56 --tscale-clamp=0.0 --vo=gpu

Expected Behavior

No flicker.

Actual Behavior

Flicker.

(Video not mine, but I can reproduce exactly the same effect, but even more severe, if you adjust refresh rate)
http://files.catbox.moe/iypqcc.mp4

What likely happens is that vo=gpu-next is switching between interpolated and exact frame, when timing matches. Which produces this jarring, lack of smoothness, broken interpolation. While vo=gpu is interpolating smoothly, we can see more blur, but this is expected.

Log File

DIY, it is easily reproducible.

Sample Files

bars_23fps.zip

I carefully read all instruction and confirm that I did the following:

• I tested with the latest mpv version to validate that the issue is not already fixed.
• I provided all required information including system and mpv version.
• I produced the log file with the exact same set of files, parameters, and conditions used in "Reproduction Steps", with the addition of --log-file=output.txt.
• I produced the log file while the behaviors described in "Actual Behavior" were actively observed.
• I attached the full, untruncated log file.
• I attached the backtrace in the case of a crash.