vo_gpu: adjust interpolation_threshold's default

When mpv attempts to play a video that is, on average, 60 FPS on a
display that is not exactly 60.00 Hz, two options try to fight each
other: `video-sync-max-video-change` and `interpolation-threshold`.
Normally, container FPS in something such as an .mp4 or a .mkv is
precise enough such that the video can be retimed exactly to the display
Hz and interpolation is not activated.

In the case of something like certain live streaming videos or other scenario
where container FPS is not known, the default option of 0.0001 for
`interpolation-threshold` is extremely low, and while
`video-sync-max-video-change` retimes the video to what it approximately
knows as the "real" FPS, this may or may not be outside of
`interpolation-threshold`'s logic at any given time, which causes
interpolation to be frequently flipped on and off giving an appearance
of stuttering or repeated frames that is oftern quite jarring and makes
a video unwatchable.

This commit changes the default of `interpolation-threshold` to 0.01,
which is the same value as `video-sync-max-video-change`, and guarantees
that if the user accepts a video being retimed to match the display,
they do not additionally have to worry about a much more
precise interpolation threshold randomly flipping on or off. No internal
logic is changed so setting `interpolation-threshold` to -1 will still
disable this logic entirely and always enable interpolation.

The documentation has been updated to reflect this change and give
context to the user for which scenarios they might want to disable
`interpolation-threshold` logic or change it to a smaller value.

1 files changed, 1 insertions, 1 deletions

diff --git a/video/out/gpu/video.c b/video/out/gpu/video.c
index 732d0a07eb..597286a550 100644
--- a/video/out/gpu/video.c
+++ b/video/out/gpu/video.c
@@ -317,7 +317,7 @@ static const struct gl_video_opts gl_video_opts_def = {
     },
     .scaler_resizes_only = 1,
     .scaler_lut_size = 6,
-    .interpolation_threshold = 0.0001,
+    .interpolation_threshold = 0.01,
     .alpha_mode = ALPHA_BLEND_TILES,
     .background = {0, 0, 0, 255},
     .gamma = 1.0f,