GPUImageVideoCameraにセットされたsessionのサイズの取得(Swift版) ref: http://qiita.com/takuya-i/items/84dd0c8d202eff4104a8

file0.txt

//VideoCameraはGPUIMageVideoCameraのインスタンス

let output = videoCamera.captureSession.outputs[self.videoCamera.captureSession.outputs.endIndex - 1] as! AVCaptureVideoDataOutput
        let setting:NSDictionary = output.videoSettings
        let width  = (setting["Width"] as! NSNumber).longValue
        let height = (setting["Height"] as! NSNumber).longValue