[Bug 1667] Regression - No Video in RealPlayer 8

[Wine Bugs]

http://bugs.winehq.com/show_bug.cgi?id=1667





------- Additional Comments From Andrew.Talbot at talbotville.com  2003-09-12 16:09 -------
Mike,

Under Windows 98SE, on my P3/450, I ran your test2.exe program twice, with a 
nominal twenty seconds between each run.  Subtracting the two QPCs and dividing 
by the timing period gave (472313655 - 448390410) / 20 = 1196162 ticks per 
second.  QPF was reported as 1193180: remarkably close.  QPC, of course, 
represents the number of clock ticks since switch-on.  Programs can measure time 
intervals by dividing differences in QPC by QPF, (i.e. tick-count-difference 
divided by ticks-per-second = seconds elapsed) so the scalings have to be 
consistent.

On my 'unscaled' version of Wine (SUSE 9.0), I also made two runs, this time 
roughly thirty seconds apart, and got (191677227390 - 178935563205) / 30 = 
424722139.5 counts per second from the two QPCs, with QPF given as 451054000.  
Not bad for a crude, manual test.

It seems that versions of Windows <= Win98SE may have used the Programmable 
Interrupt Timer (8254) chip, with its 1.19 Mhz clock (even on PCs with 
RDTSC-capable processors).  However, I suspect that other versions of Windows 
(i.e. the more 'corporate' varieties: NT, Win2k, XP) might actually use the 
RDTSC instruction, if available, thus providing the nanosecond-order resolution 
of which the CPU clocks of modern computers are capable.  So, perhaps the clock 
that Wine uses for the High-Performance Timer functions (CPU vs. PIT) should 
depend not only on the availability of the RDTSC instruction, but also on which 
version of Windows that Wine is set to emulate.

I shall seek to run your program on at least one Win XP Pro machine to see which 
clock that uses and shall report back here.

-- Andy.


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