Need to develop a custom ffmpeg filter in 'C' environment

I have a need for a custom ffmpeg filter. Basic specifications are as such: ffmpeg inputVideo1 inputVideo2 outputVideo The custom filter will focus ONLY on Alpha channel. Nothing else. The filter will progressively run through the entire inputVideo1, frame-by-frame, and duplicate every ALPHA channel pixel from inputVideo1 to inputVideo2. Essentially the filter is a temporary workaround for another filter that does not retain alpha channel as part of its video processing, so this custom plugin that you need to write is a post-processing video pass that fixes this alpha issue. Test case with images and explanation of the output can be found here: [login to view URL] or looking at the attached pdf document. A lot of the source code for this project is already written, and can be found in 'vf_overlay.c' To qualify for this project, you need to have experience working with source code libraries of either libav* or ffmpeg. Deliverable for this project is a single file source code. There will be 3 milestones for this project: 1st milestone 30% is created upon commencement of development. Milestone is released after you: a) install ffmpeg from the sourcecode using latest repo. b) run through the test-case using your built ffmpeg executable, and produce non transparent background video. (all of this is out of the box ffmpeg functionality) 2nd milestone 40%: create the source code of the plugin, and produce the desired output based on the attached pdf document. You share this output video with me, and once I approve that the output is correct, I release the milestone. 3rd milestone is 30%: a) I get the source code from you, I build the ffmpeg source with your created plugin, and verify that the output is per specifications. b) Your source code must be well documented with inline comments. You also must use best practices for creating logic to copy alpha data from one video to the next, that is, processing a 1 minute in length video cannot take more than several seconds on a powerful PC, but certainly less than a minute. If successful with this task, we have constant ongoing development, including ffmpeg/libav libraries, conversion, etc.