skip-logo.lua: fix skipping in the first two frames

mpv typically decodes and filters at least 2 frames before starting
playback. This happens during seeks, as well as when playback starts
from the beginning of the file.

skip-logo.lua receives notifications for all filtered frames, even
during seeking. It should interrupt during seeking, so as a crude
heuristic, it ignored all frames while the player was seeking. This does
not mean all these frames are skipped due to seeking (thus it's a "crude
hueristic"). In particular, it means that the first 2 frames of a video
cannot be skipped, since they're filtered within the playback restart
phase (equivalent to "seeking").

Fix this by making the heuristic slightly less crude. Since we observe
the property as "none", the property is not actually read until we do it
explicitly. By not reading it during seeking, we can let the frames
internally queue up (vf_fingerprint discards them in a ringbuffer-like
fashion if they're too many). Then, if seeking ends, we get the current
playback timestamp, and check queued up frames that are at or after that
timestamp. (In some ways, this duplicates what the player's seeking
logic does.)

A disadvantage is that this is racy. While playback-time is guaranteed
to be set when seeking changes from false to true, playback could
already have progressed to the next frame (or more) before the script
gets time to react. In theory, we could add a seek restart hook or so,
but I don't want to. A property that returns the last playback restart
time would also do it, but feels to special. Not an important problem
in practice anyway.
This commit is contained in:
wm4 2019-10-08 21:26:17 +02:00
parent 0a30a4a432
commit 68bbc55eda
1 changed files with 36 additions and 15 deletions

View File

@ -79,6 +79,8 @@ local meta_property = string.format("vf-metadata/%s", label)
local config = {} local config = {}
local cases = {} local cases = {}
local cur_bmp local cur_bmp
local seeking = false
local playback_start_pts = nil
-- Convert a hex string to an array. Convert each byte to a [0,1] float by -- Convert a hex string to an array. Convert each byte to a [0,1] float by
-- interpreting it as normalized uint8_t. -- interpreting it as normalized uint8_t.
@ -194,24 +196,12 @@ local function check_fingerprint(hex, pts)
return false return false
end end
mp.observe_property(meta_property, "none", function() local function read_frames()
local result = mp.get_property_native(meta_property) local result = mp.get_property_native(meta_property)
if result == nil then if result == nil then
return return
end end
-- Disable matching while seeking. This is not always ideal. For example,
-- the filter chain may filter frames ahead of where it will resume
-- playback (if something prefetches frames). On the other hand, the
-- skipping logic shouldn't activate when the user is trying to seek past
-- the skip frame anyway. You could be more fancy and here, and store all
-- seen frames, then apply the skipping when it's actually displayed (by
-- observing the playback time). But for now, the naive and not-always-
-- correct way seems to suffice.
if mp.get_property_bool("seeking", false) then
return
end
-- Try to get all entries. Out of laziness, assume that there are at most -- Try to get all entries. Out of laziness, assume that there are at most
-- 100 entries. (In fact, vf_fingerprint limits it to 10.) -- 100 entries. (In fact, vf_fingerprint limits it to 10.)
for i = 0, 99 do for i = 0, 99 do
@ -223,9 +213,40 @@ mp.observe_property(meta_property, "none", function()
break break
end end
if check_fingerprint(hex, pts) then local skip = false -- blame Lua for not having "continue" or "goto", not me
break
-- If seeking just stopped, there will be frames before the seek target,
-- ignore them by checking the timestamps.
if playback_start_pts ~= nil then
if pts >= playback_start_pts then
playback_start_pts = nil -- just for robustness
else
skip = true
end
end end
if not skip then
if check_fingerprint(hex, pts) then
break
end
end
end
end
mp.observe_property(meta_property, "none", function()
-- Ignore frames that are decoded/filtered during seeking.
if seeking then
return
end
read_frames()
end)
mp.observe_property("seeking", "bool", function(name, val)
seeking = val
if seeking == false then
playback_start_pts = mp.get_property_number("playback-time")
read_frames()
end end
end) end)