Media :: Save Encoded Video Steam From Encoder And Add Custom Composer Engine?

First, I want to save the encoded video stream from the encoder,And then, the encoder recieves the uncompressed video stream from camera. How can my application recieve the compressed stream from the encoder?

Second, I'd like to add the custom composer engine to media framework(opencore), And then I'll use the already-launched device, HTC Hero and Motrola Droid, etc. The custom composer engine will recieve the video stream from the encoder. And, save the stream using the custom file format. Is it possible add the custome engine using the already-lauched device? If it is posselbe, where can I find the references?