Comments for Mr Jack Games

Comment on Video (almost) direct from the iPhone by Mr Jack

Mr Jack — Fri, 18 Jun 2010 15:01:25 +0000

I probably could have done, but the OpenCV port for the iPhone doesn’t support video creation, I couldn’t find a decent library to use and I certainly didn’t want to get into writing my own.

Since it was only for my own use, using an offline tool seemed like a decent compromise.

Comment on Video (almost) direct from the iPhone by Warren

Warren — Fri, 18 Jun 2010 14:53:22 +0000

ohh so you couldnt get the video to encode directly on the iphone?

Comment on Video (almost) direct from the iPhone by Mr Jack

Mr Jack — Thu, 17 Jun 2010 12:05:58 +0000

I’m not quite sure what you mean. I wrote the file to the application data area of the iPhone, extracted it using the Organiser in XCode and then used a little .exe I wrote on the mac using OpenCV to convert to video. Finally, I used iMovie to cut the video together into the final product.

Comment on Video (almost) direct from the iPhone by Warren

Warren — Wed, 16 Jun 2010 23:58:17 +0000

Thanks for the reply. Yeah that makes sense. I’ll give that a shot in my code. One last question, did you make your own video file from a scratch binary or using the openCV libraries and offload it FTPing into your iphone?

Comment on Video (almost) direct from the iPhone by Mr Jack

Mr Jack — Wed, 16 Jun 2010 17:03:58 +0000

I work out the deltas from the objects I’m updating. When I move a renderable object, it hands the video capture a rectangle containing the area that it will change. The video capture code combines it with existing regions in a sensible fashion so that it isn’t storing multiple overlapping rectangle.

Then on the capture frame, I call glReadPixels only on those rectangles that I know have changed. Because Alien Swing has a fixed background this works nicely.

Comment on Video (almost) direct from the iPhone by Warren

Warren — Wed, 16 Jun 2010 16:51:25 +0000

Nice idea. I’m faced with a similar problem in my current app im developing and I thought of the delta compression prior to reading this but I wasn’t too sure how I’d go abouts making that file. I used glReadPixels in a previous app just for one screen shot but if you’re calculating delta pixels is that the function that is still used? You still have to call it, but you’re just saving less data from frame to frame (keyframe (more) -> transitional frame (less))

Comment on Video (almost) direct from the iPhone by Mr Jack

Mr Jack — Thu, 04 Feb 2010 11:43:22 +0000

Heh, as it turns out 90% of the glitches were because I was calling the capture code in the wrong place and thus it was capturing for the frame before the one I’d calculated the delta for.

Comment on Video (almost) direct from the iPhone by Mr Jack

Mr Jack — Wed, 03 Feb 2010 19:21:11 +0000

Aye, I could record the input and then replay. I use a Mersenne Twister for all the random stuff so I could seed it and repeat all the random elements. I did think about doing that, but I figured there’d be as much work recording and replaying reliably as there would be getting video recording working. I’m not so convinced of that now, but from here fixing up the last few glitches should be a lot less effort than starting again with a new approach.

Well done on getting the game finished, it looks fun.

Thank you. I’m really very pleased with it.

Comment on Video (almost) direct from the iPhone by Adam

Adam — Wed, 03 Feb 2010 18:56:24 +0000

Is there another form of compression given that you control everything? Instead of recording the video record the user input, replay in the simulator with the recorded user input and record your video there? (All presuming there is no unrecordable randomness.)

Well done on getting the game finished, it looks fun.

Comment on Release date confirmed by Chris

Chris — Mon, 01 Feb 2010 23:53:06 +0000

Congratulations, I hope it goes well.