OpenCV/QtCreator(Qt 5.4) 32bit versus 64

Technologist

Thank you to everyone who has helped me so far -- now I am ready to build opencv/Qt

2 basic options here:

install Qt x64* followed by MinGW x64 opencv build
install Qt 5.4 - no muss no fuss - MinGW opencv 32 (everything is ready to go 5.4)

Qt Creator 64 bit is now out*:
http://tver-soft.org/qt64

As well as MingW 64
http://sourceforge.net/projects/mingw-w64/files/Toolchains targetting Win32/Personal Builds/mingw-builds/installer/mingw-w64-install.exe/download

Any guidance on which route to take would be great. My application is an opencv video/photo object tracking one with Qt gui, etc.

SGaist

Hi,

It really depends whether you need to target or not 64bit. You should also take into account the amount of memory your application will need. If it's more than 2Gb then 32bit is out.

Technologist

Hello, if I don't know about the memory should I err on the side of x64? Are there any other performance factors involved? At the same time the 32 bit 5.4v is road tested -- don't want to overthink that.

SGaist

You can always start with 32bit and if in fact, your memory usage grows that big (and not from leaks ;-)) then switch to 64.

As for the performance, again, it depends on what you will use. Also, don't forget the possibility of using the GPU depending on the operation you want to do.

Technologist

If I write x32 code will it run ok on x64?

I dislike having you speculate but why do you think these guys are pursing 64bit opencv builds:

https://zahidhasan.wordpress.com/2014/08/19/qt-5-3-1-64-bit-mingw-windows/

"what's the motivation"?

SGaist

When you say write x32 code do you mean assembler ? If you mean build for 32bit then yes, on Windows, 32bit application can run on 64bit Windows Version. On linux you'll have to install the 32bit stuff and on OS X it's 64bit anyway since Lion. The last version supporting 32bit architectures was Snow Leopard.

I can't say for them, but most of the time it boils down to: we have 64 bit processors and OS so lets build for 64bit. IIRC MinGW 64 came a bit later

Technologist

Hi. No not assembly--does the parallax sx count? : )
I feel my choices are more informed for launching this, thank you for the teach.

Best Regards,
T.

SGaist

Well, the instruction set is a bit simpler but still, it's ASM ;)