Merge pull request #22 from kristopherjohnson/master

Update Rakefile for iOS 6.1 SDK
Update comments to refer to original script sources
Set _videoFrameFormat to KxVideoFrameFormatYUV if _videoCodecCtl->pix_fmt is either AV_PIX_FMT_YUV420P or AV_PIX_FMT_YUVJ420P
fix an issue with possible zero-length video frame
add juvj420p video stream support
add disable buffering feature
Add FFmpeg to .gitignore
Merge branch 'yuvj420p' of https://github.com/kolyvan/kxmovie