XCode编译器Apple LLVM 3.1与LLVM GCC 4.2

Question

I downloaded this project to give it a try (http://www.hatzlaha.co.il/150842/Lucas-Kanade-Detection-for-the-iPhone). It also has a released version on AppStore.

When I downloaded the source and compiled, it gave compilation errors. I changed the compiler to LLVM GCC and it instantly compiled without any errors or warnings.

Further here is what I did:

• Downloaded the app Lucas Kanade on personal iPhone. Runs as expected (ie. shows tracked points and video output).
• Deployed the above compiled app on company iPad. Here is shows the tracked points (which means the application is getting the video frames) but not able to display the video output.

General app flow:

• Grab a frame from the camera.
• Process the frame (track points).
• Output the frame, so the screen looks like its showing the camera feed, as expected.

Device details:

• iPhone: OS 5.1.1 (9B206); iPhone 4;
• iPad: OS 5.1 (9B176); iPad 2;

Questions

• Is the video output problem occurring because of the different in OS versions or because of the GCC compiler being used?
• If it is the compiler problem, would be be appropriate to put the compile errors here for resolution or do I need to start a separate Question?

I know this info might not be enough since there are a lot of unknowns, but trust me, getting into the details of the app would be a really exhaustive problem description. Let me know what more info is needed to guess the solution. I'll update it here.

Answer 1

Like you already said the info is not enough. I can just guess. The projects for tracking points uses generally their own driver for camera access. The reason, why it does not work with llvm compiler, might be that.

Just look in the project if you find any file specific to iPhone. They are mostly dat files. And maybe you find some preprocessor macros in the project like #ifdef target_iphone something like that. In that case you can contact the producer and request the driver for iPad.

I did not download and tried the project, but it is just a guess.