我使用了GPUImage库，我的前置摄像头session预设是AVCaptureSessionPresetPhoto，后置摄像头是AVCaptureSessionPresetHigh，if(self.isFrontFacingCameraPresent){[selfsetCaptureSessionPreset:AVCaptureSessionPresetHigh];}else{[selfsetCaptureSessionPreset:AVCaptureSessionPresetPhoto];}[selfrotateCamera];初始状态为使用前置摄像头，分辨率为1280x960；现