June 7, 2010
We've just released a new piece of open source software for Windows, called LICEcap! It allows one to create animated screen captures. I know, there's a lot of software out there that does this already, but none of them are both free and meet my needs, so we made LICEcap.
LICEcap has a nice UI (in that you position/size the window where you want to capture, and can move it around while recording). We support writing to .GIF directly (big thanks/credit/blame to Schwa for getting the palette generation working as well as it does), as well as to a new format called .LCF.
LCF compresses by taking a series of frames, say, 20 frames, and then dividing each frame into slices, approx 128x16px each. Each slice is then compared to the same slice on the previous frame, and (if different) encoded directly after the previous frame. zlib is used to remove redundancy (often slices don't completely change from frame to frame, i.e. scrolls or small updates will compress very well). This is all done in 16bpp, and the end result is quite good compression, and lossless (well, 16bpp lossless) quality. REAPER supports playing back the .LCF files, too. The biggest down side is high memory use during compression/decompression (20 frames of 640x480x16bpp is about 12MB, and for smooth CPU distribution you end up using twice that).
I should mention that the primary reason for us making this tool was the desire
to post animated gifs of new features in REAPER with the changelog. Hopefully
we'll follow through on that.
On a related note, tomorrow (or soonish), I plan to post my latest additions on how to make OS X applications not perform terribly (new one: avoid avoid AVOID CGBitmapContextCreateImage() like the plague. HOLY CRAP it is bad to use). Apple: please, for the love of God, either make your documentation a Wiki, or hire someone who actually writes
(multi-platform) applications with your APIs to write documentation.