timeBeginPeriod() only allows setting minimum timer resolution
to 1 ms. However, modern x86 platforms support a minimum timer
resolution of 0.5 ms. Use NtSetTimerResolution() instead for
the increased resolution, which can be set with MPV_HRT_RES.
Additionally, change the units of mp_start_hires_timers(),
mp_end_hires_timer(), MPV_HRT_RES, and MPV_HRT_MAX to nanoseconds,
in accordance with other functions used in timer.h.
With the previous series of commits, all internal usage has been
replaced by the nanosecond functions. There's not really any point in
keeping these around anymore plus there are macros for unit conversions
now so we can just axe them. It's worth noting that mpv_get_time_us()
obviously still needs to work for API reasons, but we can just divide
mp_time_ns() by 1000 to get the same thing.
There's a lot of wild 1e6, 1000, etc. lying around in the code. A macro
is much easier to read and understand at a glance. Add some helpers for
this. We don't need to convert everything now but there's some simple
things that can be done so they are included in this commit.
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.
The timestamps when making a log file is actually dependent on
MP_START_TIME. This is a 10 microsecond offset that was added to the
timer as an offset. With the nanosecond change, this unit needs to be
converted as well so the offset is the same as before. After doing that,
we need to change the various mp_time_us calls in msg to mp_time_ns and
do the right conversion. This fixes the logs timestamps (i.e. so they
aren't negative anymore).
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.
There is not much of a reason to have these wrappers around. Use POSIX
standard functions directly, and use a separate utility function to take
care of the timespec calculations. (Course POSIX for using this weird
format for time values.)
This allows getting the log at all with --no-terminal and without having
to retrieve log messages manually with the client API. The log level is
hardcoded to -v. A higher log level would lead to too much log output
(huge file sizes and latency issues due to waiting on the disk), and
isn't too useful in general anyway. For debugging, the terminal can be
used instead.
Use the time as returned by mp_time_us() for mpthread_cond_timedwait(),
instead of calculating the struct timespec value based on a timeout.
This (probably) makes it easier to wait for a specific deadline.
GetTimer() is generally replaced with mp_time_us(). Both calls return
microseconds, but the latter uses int64_t, us defined to never wrap,
and never returns 0 or negative values.
GetTimerMS() has no direct replacement. Instead the other functions are
used.
For some code, switch to mp_time_sec(), which returns the time as double
float value in seconds. The returned time is offset to program start
time, so there is enough precision left to deliver microsecond
resolution for at least 100 years. Unless it's casted to a float
(or the CPU reduces precision), which is why we still use mp_time_us()
out of paranoia in places where precision is clearly needed.
Always switch to the correct time. The whole point of the new timer
calls is that they don't wrap, and storing microseconds in unsigned int
variables would negate this.
In some cases, remove wrap-around handling for time values.
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.
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.
patch replaces '()' for the correct '(void)' in function
declarations/prototypes which have no parameters. The '()' syntax tell
thats there is a variable list of arguments, so that the compiler cannot
check this. The extra CFLAG '-Wstrict-declarations' shows those cases.
Comments about a similar patch applied to ffmpeg:
That in C++ these mean the same, but in ANSI C the semantics are
different; function() is an (obsolete) K&R C style forward declaration,
it basically means that the function can have any number and any types
of parameters, effectively completely preventing the compiler from doing
any sort of type checking. -- Erik Slagter
Defining functions with unspecified arguments is allowed but bad.
With arguments unspecified the compiler can't report an error/warning
if the function is called with incorrect arguments. -- Måns Rullgård
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@17567 b3059339-0415-0410-9bf9-f77b7e298cf2
der richter