So this system works perfectly with the Aurora Pipe Pro video card, but
when I use a decklink card I got weird results It looks like the card
sometimes jumps forward and back depending which card I use in which
configuration I tested currently 2 of their cards:
I have a thread does the following:
Loop
1. GetVideoFrame
TransferVideoFrame
aCPUTTime = getCPUTime
aDeviceTime = getDeviceTime
Calculate SleepTime For Next Frame to display
<Sleep>
LOG: aCPUTTime , aDeviceTime, Frame Transfer Time
until finished
Here the numbers:
CPU Elapsed Time Device Elapsed Time
0.033432 0.0332
0.033534 0.033767
0.033213 0.0332
0.033342 0.033334
0.033318 0.0333
0.033504 0.033533
0.033287 0.033233
0.033916 0.033934
0.033097 0.033067
0.033138 0.029462
then I went to excel to look at the elapsed time:
as you can see the CPU and device times are almost the same but if you
look at the bottom one it jumps sometimes. with 0.004, but I have seen
bigger jupmps on other cards...
Questions:
1. Has anyone seen this kind of thing in his experience?
2. Is there maybe a better way to get the device clock? Maybe through
coreAudio API's?
3. Nnyone found a good workarround to this kind of problem? Like maybe
adjusting my reference clock with the difference from the cpu time and
device time....
thx,
mvo
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