Linux and macOS already use nanosecond resolution for their sleep
functions. It was just being converted from microseconds before. Since
we have mp_time_ns now, go ahead and bump the precision here. The timer
for windows uses some timeBeginPeriod thing which I'm not sure what it
does really but whatever just convert the units to ms like they were
doing before. There's really no reason to keep the mp_sleep_us helper
around. A multiplication by 1000 is trivial and underlying OS clocks
have nanosecond precision.
Before this commit, timeBeginPeriod(1) was set once when mpv starts,
and the timers remained hi-res till mpv exits.
Now we do the same as before on Windows version < 10.
On Windows 10+ we now use timeBeginPeriod if needed, per timeout.
To force a mode regardless of Windows version, set env MPV_HRT:
- "always": the old behavior - hires timers as long as mpv runs.
- "perwait": sets 1ms timer resolution if timeout <= 50ms.
- "never": don't use timeBeginPeriod at all.
It was observed that on Windows 10 we lose about 0.5ms accuracy of
timeouts with "perwait" mode (acceptable), but otherwise it works
well for continuous timeouts (one after the other) and random ones.
On Windows 7 with "perwait": continous timeouts are accurate, but
random timeouts (after some time without timeouts) have bad
accuracy - roughly 16ms resolution instead of the requested 1ms.
Windows 8 was not tested, so to err on the side of caution, we keep
the legacy behavior "always" by default.
All authors have agreed, with the following exceptions:
e68d7f6858: wight wasn't asked (I think...), but even if he modified the
patch he applied, all code added by it was removed again later.
cb7768f9bb: nick could not be reached, but the declarations he added as
well as the full timer.c file were deleted again in cff81fe498 and
f800a42e45 (did it really take 6 years to remove unused declarations?).
ffaf4af230: it looks like this person wasn't contacted, but the code
added was removed again in f544bcf105.
clock_gettime is implemented in winpthreads, so it's unavailable when
mpv is compiled with its internal pthreads implementation. This makes
mp_raw_time_us fall back to gettimeofday(), which can cause an assert
failure in mp_add_timeout() when the system clock is changed. Use
QueryPerformanceCounter instead.
The clock_gettime(CLOCK_MONOTONIC) implementation in winpthreads uses
QueryPerformanceCounter anyway, so there shouldn't be any change in
behaviour.
This was called for formal reasons at best. The way it does this is
somewhat dangerous, because if libmpv is unloaded as DLL, this would
attempt to call a dangling function pointer.
(No, we don't want an extra DllMain entrypoint just for win32.)
This avoids trouble if another mpv instance is initialized in the same
process.
Since timeBeginPeriod/timeEndPeriod are hereby not easily matched
anymore, use an atexit() handler to call timeEndPeriod, so that we
can be sure these calls are matched, even if we allow multiple
initializations later when introducing the client API.
Make OS specific timer code export a mp_raw_time_us() function, and
add generic implementations of GetTimer()/GetTimerMS() using this
function. New mpv code is supposed to call mp_time_us() in situations
where precision is absolutely needed, or mp_time_s() otherwise.
Make it so that mp_time_us() will return a value near program start.
We don't set it to 0 though to avoid confusion with relative vs.
absolute time. Instead, pick an arbitrary offset.
Move the test program in timer-darwin.c to timer.c, and modify it to
work with the generic timer functions.
The libdvdread4 and libdvdnav directories, which are externals in the
svn repository, are at least for now not included in any form. I added
configure checks to automatically disable internal libdvdread and
libdvdnav if the corresponding directories are not present; if they're
added manually then things work the same as in svn.
Move the code calculating time delta since last query out of the
platform-specific drivers and into mplayer.c. The platform-specific
drivers now return absolute values only.
The way the code in timer-darwin.c uses doubles in wrapping arithmetic
looks questionable and this change might make problems in it more
visible.
Dudemanguy