回复： Why do some AVI formats not work properly with IMAQ?

[colinzhang]

Sorry, still can't open your code. I understand you, maybe it is really codec issue, i am not sure. NI also integrate this code to DLL file, we can't find out how it work. 

[Austin55]

I've tried saving the project as a compatable file type again. I don't suppose you happen to have any idea of the difference between the two AVI files I uploaded?

[colinzhang · Accepted solution]

ooh, yes, should be the different codec. It is really different. Thank you, let me know more. 

http://www.ni.com/white-paper/14466/en/

[Austin55]

Thank you very much! I didn't realize I had to do more than convert it into an AVI format. I changed the video format to MJPEG and it now works fine.

To anyone trying to solve this problem, I was using MediaCoder, but there are other freeware programs avalible. There are a few options here: http://www.ehow.com/how_7255268_convert-avi-codecs.html

[rolfk]

AVI is just a container format. The video and sound streams in it can be coded in many different formats, each of them needing its apropriate codec installed on your machine.

While NI-IMAQ is indeed provided as compiled shared library (DLL), the actual code responsible to deal with your AVI files is Microsoft DirectX which IMAQ provides just a wrapper to better integrate with the LabVIEW system. There is nothing you could learn from looking at the NI IMAQ portion of that code as to why it works with one AVI file and not with the other, as all the relevant handling is really done in Microsoft DirectX. And that code is not accessible either except through special Microsoft shared source code licenses with very restrictive conditions. Even then the actual handling of the various stream formats is all done by dynamically loading the appropriate codec component DLL which can be from many different sources and doesn't have to necesseraly come from Microsoft at all.