How to switch between frames with in a video file

I am working on my project of switching between the frame within a multicast environment.

Consider that i have two streams of same video file. one stream is watermarked with say 0 and another stream watermarked with 1. Depending on a key I have to switch between these two streams. How should I embed switching point within the frames?

EXAMPLE:

开发者_StackOverflow社区In the figure above the KEY VALUE is 010. The key value indicates which watermarked frame is to be selected. So in the example shown, the first frame in the output is from STREAM1 (watermark 0), Second frame is from STREAM2 (watermark 1) and the third frame is from STREAM1 (watermark 0) and so on.

This is an interesting idea to add security check on video.

If you are switching the frames - before encoding, there is really no problem. You can just have any two bank of video stream and give it to the encoder, it would work straight.

If you have an encoded stream, this is not trivial, because you cannot really do this. In this case, you can switch arbitrarily between any two GOPs. Assuming that, both streams's GOPs are fully aligned.