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Thread: Slow performances using Bitmap/GDI

  1. #16
    Join Date
    Apr 2000
    Location
    Belgium (Europe)
    Posts
    4,626

    Re: Slow performances using Bitmap/GDI

    Quote Originally Posted by golanshahar View Post
    Out of curiosity I made this quick & dirty test on my nVidia Quarto 1000m
    I wrote this sample code:

    I made only the capture function + getting bits without any manipulations.
    The results are ~30 milisec/ screen capture which leads roughly to 33 frames/sec (on my laptop of course )
    looks suspiciously high... It could be that that model videocard is "unusually" fast at capture. We test nvidia/ati/other cards for this on a fairly regular basis, but the 1000m isn't on our list for some reason, might be because it's only available as an embedded video on laptops, which would make it sorta pointless for our purposes.

    or something else is funky...

    1) what OS ? is desktop composition enabled ? is the "Aqua" enabled ?
    2) what else was running on the PC ?
    3) because you aren't doing anything with the bits and nothing else is running, you're maybe calling the Capture() too fast, causing 2 captures to fall inside the same desktop composition cycle, and thus use the same composed bitmap as source.

    THe challenge in the above is to actually capture at a high framerate while there is in fact something with that high framerate being output to screen. otherwise it's sort of defeating the purpose.

  2. #17
    Join Date
    May 2005
    Posts
    4,954

    Re: Slow performances using Bitmap/GDI

    Quote Originally Posted by OReubens View Post
    looks suspiciously high... It could be that that model videocard is "unusually" fast at capture. We test nvidia/ati/other cards for this on a fairly regular basis, but the 1000m isn't on our list for some reason, might be because it's only available as an embedded video on laptops, which would make it sorta pointless for our purposes.

    or something else is funky...

    1) what OS ? is desktop composition enabled ? is the "Aqua" enabled ?
    2) what else was running on the PC ?
    3) because you aren't doing anything with the bits and nothing else is running, you're maybe calling the Capture() too fast, causing 2 captures to fall inside the same desktop composition cycle, and thus use the same composed bitmap as source.

    THe challenge in the above is to actually capture at a high framerate while there is in fact something with that high framerate being output to screen. otherwise it's sort of defeating the purpose.
    About the settings:
    Dell laptop precision M4600
    8GB ram
    Intel i72720QM 2.2GHz
    OS win7 64 bit
    Desktop composition is enabled.
    Aqua is off.
    The pc runs several program such VS/office the cpu is idle if this what interest you.

    I don’t think that 2 captures can fall in the same iteration because it sync call, I did verify that indeed in each call I am getting pixels (I memset the buffer before) so its indeed working.

    About the frequency its still mystery because usually you want to log what user does 20 frames/sec if more than enough for that so I still curious what is the intend.

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