grab video digitizer dimension

Dec 6, 2011 at 7:29pm

grab video digitizer dimension

hello,
I want to give the user of my patch the choice to use any of the “video digitizer” available on its computer with jit.qt.grab.
Say, the built-in iSight is 640×480 and any DV camera plug via Firewire is 720×576 but it seems that jit.qt.grab got only the resolution provided with the “dim xxx xxx” message or attribute. it doesn’t seems to have any “adapt” kind attribute.
I’ve been searching but cannot figure out how I can “grab” the dimension of the video digitizer I use and adapt the matrix outputed by jit.qt.grab whith the right dimension.
any help ?
thank’s a lot.

#60511
Dec 7, 2011 at 2:12pm

Still searching.
I can give a @dim attribute to jit.qt.grab that fits for any 4/3 video input.
But what if my firewire cam is in 16/9 ?
if my @dim attribute reflect the width of my screen (1440 x 900), my 4/3 camera appears with a wrong scale…
do I really need to ask the user to search for the cam definition and enter it manualy before use it ?
any help really appreciated.

#217800
Dec 8, 2011 at 5:00pm

Opening Quick time, choosing file>new video recording, I can choose to record from any video device recognize by my system.
Looking at the inspector, I notice that QT records at the exact dimension of the choosen device (640 x 480 for the iSight, 720 x 576 for the DV cam).
So, Quick time do as the capability to grab the video device dimensions.
Do I miss something obvious or jit.qt.grab just do not have this capability implemented ?
Any help much appreciated

#217801
Dec 8, 2011 at 5:41pm

Oups, may be I spoke too fast.
720 x 576 only if I choose “maximum quality”
680 x 480 for “High quality”
320 x 240 for “medium quality”
all are 4/3 scaled image which are both the scale for my iSight and my DV camera.
So I can’t know if Quick Time “knows” that the maximum dimension of my camera is 720 x 576.
Does any one owning a 16/9 camera can tell me if QuickTime can at least recognize the scale of the video device it uses ?

#217802

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