Qt-interest Archive, January 2008
Moving images from BMPs
Message 1 in thread
Hello,
I am trying to convert a Windows native video display application into a
Qt3 based equivalent. The source app draws 16 independent moving images
(from 16 cameras) into a 4 x 4 array matrix of display areas. It uses
the windows DrawDibDraw() function to do this and it works well.
If its not to broad a question, what is the quickest way to do a similar
thing with Qt. My initial work has used QPixmap loaded from the
successive BMPs I get from the video decoder but I see severe flicker.
The picture itself is fine however. I understand why this would be the
case so now I guess I'm fishing for some hints as to the most efficient
path to take from here.
Regards and thanks,
John
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Message 2 in thread
Hi,
I get my images directly from a camera capture api and do it like this:
I use a Qimage wich is refreshed and redrawn at the same interval as the fps from the camera (with a Qtimer) this seems to work fine
on a fast machine (some latency on a slower one when enlarging the window to the full screen) but i don't know if there's a better way...
wkr,
Jasper
> Date: Fri, 11 Jan 2008 13:30:12 +1100> From: qt@xxxxxxxxxx> To: qt-interest@xxxxxxxxxxxxx> Subject: Moving images from BMPs > > Hello,> > I am trying to convert a Windows native video display application into a > Qt3 based equivalent. The source app draws 16 independent moving images > (from 16 cameras) into a 4 x 4 array matrix of display areas. It uses > the windows DrawDibDraw() function to do this and it works well.> > If its not to broad a question, what is the quickest way to do a similar > thing with Qt. My initial work has used QPixmap loaded from the > successive BMPs I get from the video decoder but I see severe flicker. > The picture itself is fine however. I understand why this would be the > case so now I guess I'm fishing for some hints as to the most efficient > path to take from here.> > Regards and thanks,> John> > > --> To unsubscribe - send a mail to qt-interest-request@xxxxxxxxxxxxx with "unsubscribe" in the subject or the body.> List archive and information: http://lists.trolltech.com/qt-interest/>
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Message 3 in thread
John Colville wrote:
> I am trying to convert a Windows native video display
> application into a Qt3 based equivalent.
Is there a reason why you don't use Qt4? Qt3's lifecycle has ended and
it's not recommended to use it on new projects.
> If its not to broad a question, what is the quickest way to
> do a similar
> thing with Qt. My initial work has used QPixmap loaded from the
> successive BMPs I get from the video decoder but I see severe
> flicker.
Are you saying you get the video stream as successive BMP files that you
have to individually open and display from harddisk?
This doesn't sound like an efficient way to stream the data.
On the other hand, if that is what the old application did, you should
be able to do the same efficiently in Qt.
Cheers,
Peter
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Message 4 in thread
Peter,
Its Qt3 (for now) because upgrading the other 300K lines of non-video
related code is just way too horrible to contemplate !
The images arrive via the network from a DVR that streams them into a
proprietary library that gives me easy access to successive BMPs in
memory. I've done some more reading and it looks like using the bitblt()
method somehow could be very useful.
John
Peter Prade wrote:
>John Colville wrote:
>
>
>>I am trying to convert a Windows native video display
>>application into a Qt3 based equivalent.
>>
>>
>
>Is there a reason why you don't use Qt4? Qt3's lifecycle has ended and
>it's not recommended to use it on new projects.
>
>
>
>>If its not to broad a question, what is the quickest way to
>>do a similar
>>thing with Qt. My initial work has used QPixmap loaded from the
>>successive BMPs I get from the video decoder but I see severe
>>flicker.
>>
>>
>
>Are you saying you get the video stream as successive BMP files that you
>have to individually open and display from harddisk?
>This doesn't sound like an efficient way to stream the data.
>
>On the other hand, if that is what the old application did, you should
>be able to do the same efficiently in Qt.
>
>Cheers,
>Peter
>
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>To unsubscribe - send a mail to qt-interest-request@xxxxxxxxxxxxx with "unsubscribe" in the subject or the body.
>List archive and information: http://lists.trolltech.com/qt-interest/
>
>
>
>
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